Address Details

contract

// SPDX-License-Identifier: MIT

pragma solidity >=0.7.0 <0.9.0;
pragma experimental ABIEncoderV2;

/**
* @dev EIP2362 Interface for pull oracles
* https://github.com/adoracles/EIPs/blob/erc-2362/EIPS/eip-2362.md
*/
interface IERC2362
{
	/**
	 * @dev Exposed function pertaining to EIP standards
	 * @param _id bytes32 ID of the query
	 * @return int,uint,uint returns the value, timestamp, and status code of query
	 */
	function valueFor(bytes32 _id) external view returns(int256,uint256,uint256);
}

/// @title The Witnet Data Request basic interface.
/// @author The Witnet Foundation.
interface IWitnetRequest {
    
    /// @notice A `IWitnetRequest` is constructed around a `bytes` value containing 
    /// @notice a well-formed Witnet Data Request using Protocol Buffers.
    function bytecode() external view returns (bytes memory);

    /// @notice Returns SHA256 hash of Witnet Data Request as CBOR-encoded bytes.
    function hash() external view returns (bytes32);
}

/// @title A convenient wrapper around the `bytes memory` type that exposes a buffer-like interface
/// @notice The buffer has an inner cursor that tracks the final offset of every read, i.e. any subsequent read will
/// start with the byte that goes right after the last one in the previous read.
/// @dev `uint32` is used here for `cursor` because `uint16` would only enable seeking up to 8KB, which could in some
/// theoretical use cases be exceeded. Conversely, `uint32` supports up to 512MB, which cannot credibly be exceeded.
/// @author The Witnet Foundation.
library WitnetBuffer {

  error EmptyBuffer();
  error IndexOutOfBounds(uint index, uint range);
  error MissingArgs(uint expected, uint given);

  /// Iterable bytes buffer.
  struct Buffer {
      bytes data;
      uint cursor;
  }

  // Ensures we access an existing index in an array
  modifier withinRange(uint index, uint _range) {
    if (index > _range) {
      revert IndexOutOfBounds(index, _range);
    }
    _;
  }

  /// @notice Concatenate undefinite number of bytes chunks.
  /// @dev Faster than looping on `abi.encodePacked(output, _buffs[ix])`.
  function concat(bytes[] memory _buffs)
    internal pure
    returns (bytes memory output)
  {
    unchecked {
      uint destinationPointer;
      uint destinationLength;
      assembly {
        // get safe scratch location
        output := mload(0x40)
        // set starting destination pointer
        destinationPointer := add(output, 32)
      }      
      for (uint ix = 1; ix <= _buffs.length; ix ++) {  
        uint source;
        uint sourceLength;
        uint sourcePointer;        
        assembly {
          // load source length pointer
          source := mload(add(_buffs, mul(ix, 32)))
          // load source length
          sourceLength := mload(source)
          // sets source memory pointer
          sourcePointer := add(source, 32)
        }
        memcpy(
          destinationPointer,
          sourcePointer,
          sourceLength
        );
        assembly {          
          // increase total destination length
          destinationLength := add(destinationLength, sourceLength)
          // sets destination memory pointer
          destinationPointer := add(destinationPointer, sourceLength)
        }
      }
      assembly {
        // protect output bytes
        mstore(output, destinationLength)
        // set final output length
        mstore(0x40, add(mload(0x40), add(destinationLength, 32)))
      }
    }
  }

  function fork(WitnetBuffer.Buffer memory buffer)
    internal pure
    returns (WitnetBuffer.Buffer memory)
  {
    return Buffer(
      buffer.data,
      buffer.cursor
    );
  }

  function mutate(
      WitnetBuffer.Buffer memory buffer,
      uint length,
      bytes memory pokes
    )
    internal pure
    withinRange(length, buffer.data.length - buffer.cursor + 1)
  {
    bytes[] memory parts = new bytes[](3);
    parts[0] = peek(
      buffer,
      0,
      buffer.cursor
    );
    parts[1] = pokes;
    parts[2] = peek(
      buffer,
      buffer.cursor + length,
      buffer.data.length - buffer.cursor - length
    );
    buffer.data = concat(parts);
  }

  /// @notice Read and consume the next byte from the buffer.
  /// @param buffer An instance of `Buffer`.
  /// @return The next byte in the buffer counting from the cursor position.
  function next(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor, buffer.data.length)
    returns (bytes1)
  {
    // Return the byte at the position marked by the cursor and advance the cursor all at once
    return buffer.data[buffer.cursor ++];
  }

  function peek(
      WitnetBuffer.Buffer memory buffer,
      uint offset,
      uint length
    )
    internal pure
    withinRange(offset + length, buffer.data.length)
    returns (bytes memory)
  {
    bytes memory data = buffer.data;
    bytes memory peeks = new bytes(length);
    uint destinationPointer;
    uint sourcePointer;
    assembly {
      destinationPointer := add(peeks, 32)
      sourcePointer := add(add(data, 32), offset)
    }
    memcpy(
      destinationPointer,
      sourcePointer,
      length
    );
    return peeks;
  }

  // @notice Extract bytes array from buffer starting from current cursor.
  /// @param buffer An instance of `Buffer`.
  /// @param length How many bytes to peek from the Buffer.
  // solium-disable-next-line security/no-assign-params
  function peek(
      WitnetBuffer.Buffer memory buffer,
      uint length
    )
    internal pure
    withinRange(length, buffer.data.length - buffer.cursor)
    returns (bytes memory)
  {
    return peek(
      buffer,
      buffer.cursor,
      length
    );
  }

  /// @notice Read and consume a certain amount of bytes from the buffer.
  /// @param buffer An instance of `Buffer`.
  /// @param length How many bytes to read and consume from the buffer.
  /// @return output A `bytes memory` containing the first `length` bytes from the buffer, counting from the cursor position.
  function read(Buffer memory buffer, uint length)
    internal pure
    withinRange(buffer.cursor + length, buffer.data.length)
    returns (bytes memory output)
  {
    // Create a new `bytes memory destination` value
    output = new bytes(length);
    // Early return in case that bytes length is 0
    if (length > 0) {
      bytes memory input = buffer.data;
      uint offset = buffer.cursor;
      // Get raw pointers for source and destination
      uint sourcePointer;
      uint destinationPointer;
      assembly {
        sourcePointer := add(add(input, 32), offset)
        destinationPointer := add(output, 32)
      }
      // Copy `length` bytes from source to destination
      memcpy(
        destinationPointer,
        sourcePointer,
        length
      );
      // Move the cursor forward by `length` bytes
      seek(
        buffer,
        length,
        true
      );
    }
  }
  
  /// @notice Read and consume the next 2 bytes from the buffer as an IEEE 754-2008 floating point number enclosed in an
  /// `int32`.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 5 decimal orders so as to get a fixed precision of 5 decimal positions, which should be OK for most `float16`
  /// use cases. In other words, the integer output of this method is 10,000 times the actual value. The input bytes are
  /// expected to follow the 16-bit base-2 format (a.k.a. `binary16`) in the IEEE 754-2008 standard.
  /// @param buffer An instance of `Buffer`.
  /// @return result The `int32` value of the next 4 bytes in the buffer counting from the cursor position.
  function readFloat16(Buffer memory buffer)
    internal pure
    returns (int32 result)
  {
    uint32 value = readUint16(buffer);
    // Get bit at position 0
    uint32 sign = value & 0x8000;
    // Get bits 1 to 5, then normalize to the [-15, 16] range so as to counterweight the IEEE 754 exponent bias
    int32 exponent = (int32(value & 0x7c00) >> 10) - 15;
    // Get bits 6 to 15
    int32 fraction = int32(value & 0x03ff);
    // Add 2^10 to the fraction if exponent is not -15
    if (exponent != -15) {
      fraction |= 0x400;
    } else if (exponent == 16) {
      revert(
        string(abi.encodePacked(
          "WitnetBuffer.readFloat16: ",
          sign != 0 ? "negative" : hex"",
          " infinity"
        ))
      );
    }
    // Compute `2 ^ exponent · (1 + fraction / 1024)`
    if (exponent >= 0) {
      result = int32(int(
        int(1 << uint256(int256(exponent)))
          * 10000
          * fraction
      ) >> 10);
    } else {
      result = int32(int(
        int(fraction)
          * 10000
          / int(1 << uint(int(- exponent)))
      ) >> 10);
    }
    // Make the result negative if the sign bit is not 0
    if (sign != 0) {
      result *= -1;
    }
  }

  /// @notice Consume the next 4 bytes from the buffer as an IEEE 754-2008 floating point number enclosed into an `int`.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 9 decimal orders so as to get a fixed precision of 9 decimal positions, which should be OK for most `float32`
  /// use cases. In other words, the integer output of this method is 10^9 times the actual value. The input bytes are
  /// expected to follow the 64-bit base-2 format (a.k.a. `binary32`) in the IEEE 754-2008 standard.
  /// @param buffer An instance of `Buffer`.
  /// @return result The `int` value of the next 8 bytes in the buffer counting from the cursor position.
  function readFloat32(Buffer memory buffer)
    internal pure
    returns (int result)
  {
    uint value = readUint32(buffer);
    // Get bit at position 0
    uint sign = value & 0x80000000;
    // Get bits 1 to 8, then normalize to the [-127, 128] range so as to counterweight the IEEE 754 exponent bias
    int exponent = (int(value & 0x7f800000) >> 23) - 127;
    // Get bits 9 to 31
    int fraction = int(value & 0x007fffff);
    // Add 2^23 to the fraction if exponent is not -127
    if (exponent != -127) {
      fraction |= 0x800000;
    } else if (exponent == 128) {
      revert(
        string(abi.encodePacked(
          "WitnetBuffer.readFloat32: ",
          sign != 0 ? "negative" : hex"",
          " infinity"
        ))
      );
    }
    // Compute `2 ^ exponent · (1 + fraction / 2^23)`
    if (exponent >= 0) {
      result = (
        int(1 << uint(exponent))
          * (10 ** 9)
          * fraction
      ) >> 23;
    } else {
      result = (
        fraction 
          * (10 ** 9)
          / int(1 << uint(-exponent)) 
      ) >> 23;
    }
    // Make the result negative if the sign bit is not 0
    if (sign != 0) {
      result *= -1;
    }
  }

  /// @notice Consume the next 8 bytes from the buffer as an IEEE 754-2008 floating point number enclosed into an `int`.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 15 decimal orders so as to get a fixed precision of 15 decimal positions, which should be OK for most `float64`
  /// use cases. In other words, the integer output of this method is 10^15 times the actual value. The input bytes are
  /// expected to follow the 64-bit base-2 format (a.k.a. `binary64`) in the IEEE 754-2008 standard.
  /// @param buffer An instance of `Buffer`.
  /// @return result The `int` value of the next 8 bytes in the buffer counting from the cursor position.
  function readFloat64(Buffer memory buffer)
    internal pure
    returns (int result)
  {
    uint value = readUint64(buffer);
    // Get bit at position 0
    uint sign = value & 0x8000000000000000;
    // Get bits 1 to 12, then normalize to the [-1023, 1024] range so as to counterweight the IEEE 754 exponent bias
    int exponent = (int(value & 0x7ff0000000000000) >> 52) - 1023;
    // Get bits 6 to 15
    int fraction = int(value & 0x000fffffffffffff);
    // Add 2^52 to the fraction if exponent is not -1023
    if (exponent != -1023) {
      fraction |= 0x10000000000000;
    } else if (exponent == 1024) {
      revert(
        string(abi.encodePacked(
          "WitnetBuffer.readFloat64: ",
          sign != 0 ? "negative" : hex"",
          " infinity"
        ))
      );
    }
    // Compute `2 ^ exponent · (1 + fraction / 1024)`
    if (exponent >= 0) {
      result = (
        int(1 << uint(exponent))
          * (10 ** 15)
          * fraction
      ) >> 52;
    } else {
      result = (
        fraction 
          * (10 ** 15)
          / int(1 << uint(-exponent)) 
      ) >> 52;
    }
    // Make the result negative if the sign bit is not 0
    if (sign != 0) {
      result *= -1;
    }
  }

  // Read a text string of a given length from a buffer. Returns a `bytes memory` value for the sake of genericness,
  /// but it can be easily casted into a string with `string(result)`.
  // solium-disable-next-line security/no-assign-params
  function readText(
      WitnetBuffer.Buffer memory buffer,
      uint64 length
    )
    internal pure
    returns (bytes memory text)
  {
    text = new bytes(length);
    unchecked {
      for (uint64 index = 0; index < length; index ++) {
        uint8 char = readUint8(buffer);
        if (char & 0x80 != 0) {
          if (char < 0xe0) {
            char = (char & 0x1f) << 6
              | (readUint8(buffer) & 0x3f);
            length -= 1;
          } else if (char < 0xf0) {
            char  = (char & 0x0f) << 12
              | (readUint8(buffer) & 0x3f) << 6
              | (readUint8(buffer) & 0x3f);
            length -= 2;
          } else {
            char = (char & 0x0f) << 18
              | (readUint8(buffer) & 0x3f) << 12
              | (readUint8(buffer) & 0x3f) << 6  
              | (readUint8(buffer) & 0x3f);
            length -= 3;
          }
        }
        text[index] = bytes1(char);
      }
      // Adjust text to actual length:
      assembly {
        mstore(text, length)
      }
    }
  }

  /// @notice Read and consume the next byte from the buffer as an `uint8`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint8` value of the next byte in the buffer counting from the cursor position.
  function readUint8(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor, buffer.data.length)
    returns (uint8 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 1), offset))
    }
    buffer.cursor ++;
  }

  /// @notice Read and consume the next 2 bytes from the buffer as an `uint16`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint16` value of the next 2 bytes in the buffer counting from the cursor position.
  function readUint16(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor + 2, buffer.data.length)
    returns (uint16 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 2), offset))
    }
    buffer.cursor += 2;
  }

  /// @notice Read and consume the next 4 bytes from the buffer as an `uint32`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint32` value of the next 4 bytes in the buffer counting from the cursor position.
  function readUint32(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor + 4, buffer.data.length)
    returns (uint32 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 4), offset))
    }
    buffer.cursor += 4;
  }

  /// @notice Read and consume the next 8 bytes from the buffer as an `uint64`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint64` value of the next 8 bytes in the buffer counting from the cursor position.
  function readUint64(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor + 8, buffer.data.length)
    returns (uint64 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 8), offset))
    }
    buffer.cursor += 8;
  }

  /// @notice Read and consume the next 16 bytes from the buffer as an `uint128`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint128` value of the next 16 bytes in the buffer counting from the cursor position.
  function readUint128(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor + 16, buffer.data.length)
    returns (uint128 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 16), offset))
    }
    buffer.cursor += 16;
  }

  /// @notice Read and consume the next 32 bytes from the buffer as an `uint256`.
  /// @param buffer An instance of `Buffer`.
  /// @return value The `uint256` value of the next 32 bytes in the buffer counting from the cursor position.
  function readUint256(Buffer memory buffer)
    internal pure
    withinRange(buffer.cursor + 32, buffer.data.length)
    returns (uint256 value)
  {
    bytes memory data = buffer.data;
    uint offset = buffer.cursor;
    assembly {
      value := mload(add(add(data, 32), offset))
    }
    buffer.cursor += 32;
  }

  /// @notice Count number of required parameters for given bytes arrays
  /// @dev Wildcard format: "\#\", with # in ["0".."9"].
  /// @param input Bytes array containing strings.
  /// @param count Highest wildcard index found, plus 1.
  function argsCountOf(bytes memory input)
    internal pure
    returns (uint8 count)
  {
    if (input.length < 3) {
      return 0;
    }
    unchecked {
      uint ix = 0; 
      uint length = input.length - 2;
      for (; ix < length; ) {
        if (
          input[ix] == bytes1("\\")
            && input[ix + 2] == bytes1("\\")
            && input[ix + 1] >= bytes1("0")
            && input[ix + 1] <= bytes1("9")
        ) {
          uint8 ax = uint8(uint8(input[ix + 1]) - uint8(bytes1("0")) + 1);
          if (ax > count) {
            count = ax;
          }
          ix += 3;
        } else {
          ix ++;
        }
      }
    }
  }

  /// @notice Replace bytecode indexed wildcards by correspondent substrings.
  /// @dev Wildcard format: "\#\", with # in ["0".."9"].
  /// @param input Bytes array containing strings.
  /// @param args Array of substring values for replacing indexed wildcards.
  /// @return output Resulting bytes array after replacing all wildcards.
  /// @return hits Total number of replaced wildcards.
  function replace(bytes memory input, string[] memory args)
    internal pure
    returns (bytes memory output, uint hits)
  {
    uint ix = 0; uint lix = 0;
    uint inputLength;
    uint inputPointer;
    uint outputLength;
    uint outputPointer;    
    uint source;
    uint sourceLength;
    uint sourcePointer;

    if (input.length < 3) {
      return (input, 0);
    }
    
    assembly {
      // set starting input pointer
      inputPointer := add(input, 32)
      // get safe output location
      output := mload(0x40)
      // set starting output pointer
      outputPointer := add(output, 32)
    }         

    unchecked {
      uint length = input.length - 2;
      for (; ix < length; ) {
        if (
          input[ix] == bytes1("\\")
            && input[ix + 2] == bytes1("\\")
            && input[ix + 1] >= bytes1("0")
            && input[ix + 1] <= bytes1("9")
        ) {
          inputLength = (ix - lix);
          if (ix > lix) {
            memcpy(
              outputPointer,
              inputPointer,
              inputLength
            );
            inputPointer += inputLength + 3;
            outputPointer += inputLength;
          } else {
            inputPointer += 3;
          }
          uint ax = uint(uint8(input[ix + 1]) - uint8(bytes1("0")));
          if (ax >= args.length) {
            revert MissingArgs(ax + 1, args.length);
          }
          assembly {
            source := mload(add(args, mul(32, add(ax, 1))))
            sourceLength := mload(source)
            sourcePointer := add(source, 32)      
          }        
          memcpy(
            outputPointer,
            sourcePointer,
            sourceLength
          );
          outputLength += inputLength + sourceLength;
          outputPointer += sourceLength;
          ix += 3;
          lix = ix;
          hits ++;
        } else {
          ix ++;
        }
      }
      ix = input.length;    
    }
    if (outputLength > 0) {
      if (ix > lix ) {
        memcpy(
          outputPointer,
          inputPointer,
          ix - lix
        );
        outputLength += (ix - lix);
      }
      assembly {
        // set final output length
        mstore(output, outputLength)
        // protect output bytes
        mstore(0x40, add(mload(0x40), add(outputLength, 32)))
      }
    }
    else {
      return (input, 0);
    }
  }

  /// @notice Replace string indexed wildcards by correspondent substrings.
  /// @dev Wildcard format: "\#\", with # in ["0".."9"].
  /// @param input String potentially containing wildcards.
  /// @param args Array of substring values for replacing indexed wildcards.
  /// @return output Resulting string after replacing all wildcards.
  function replace(string memory input, string[] memory args)
    internal pure
    returns (string memory)
  {
    (bytes memory _outputBytes, ) = replace(bytes(input), args);
    return string(_outputBytes);
  }

  /// @notice Move the inner cursor of the buffer to a relative or absolute position.
  /// @param buffer An instance of `Buffer`.
  /// @param offset How many bytes to move the cursor forward.
  /// @param relative Whether to count `offset` from the last position of the cursor (`true`) or the beginning of the
  /// buffer (`true`).
  /// @return The final position of the cursor (will equal `offset` if `relative` is `false`).
  // solium-disable-next-line security/no-assign-params
  function seek(
      Buffer memory buffer,
      uint offset,
      bool relative
    )
    internal pure
    withinRange(offset, buffer.data.length)
    returns (uint)
  {
    // Deal with relative offsets
    if (relative) {
      offset += buffer.cursor;
    }
    buffer.cursor = offset;
    return offset;
  }

  /// @notice Move the inner cursor a number of bytes forward.
  /// @dev This is a simple wrapper around the relative offset case of `seek()`.
  /// @param buffer An instance of `Buffer`.
  /// @param relativeOffset How many bytes to move the cursor forward.
  /// @return The final position of the cursor.
  function seek(
      Buffer memory buffer,
      uint relativeOffset
    )
    internal pure
    returns (uint)
  {
    return seek(
      buffer,
      relativeOffset,
      true
    );
  }

  /// @notice Copy bytes from one memory address into another.
  /// @dev This function was borrowed from Nick Johnson's `solidity-stringutils` lib, and reproduced here under the terms
  /// of [Apache License 2.0](https://github.com/Arachnid/solidity-stringutils/blob/master/LICENSE).
  /// @param dest Address of the destination memory.
  /// @param src Address to the source memory.
  /// @param len How many bytes to copy.
  // solium-disable-next-line security/no-assign-params
  function memcpy(
      uint dest,
      uint src,
      uint len
    )
    private pure
  {
    unchecked {
      // Copy word-length chunks while possible
      for (; len >= 32; len -= 32) {
        assembly {
          mstore(dest, mload(src))
        }
        dest += 32;
        src += 32;
      }
      if (len > 0) {
        // Copy remaining bytes
        uint _mask = 256 ** (32 - len) - 1;
        assembly {
          let srcpart := and(mload(src), not(_mask))
          let destpart := and(mload(dest), _mask)
          mstore(dest, or(destpart, srcpart))
        }
      }
    }
  }

}

/// @title A minimalistic implementation of “RFC 7049 Concise Binary Object Representation”
/// @notice This library leverages a buffer-like structure for step-by-step decoding of bytes so as to minimize
/// the gas cost of decoding them into a useful native type.
/// @dev Most of the logic has been borrowed from Patrick Gansterer’s cbor.js library: https://github.com/paroga/cbor-js
/// @author The Witnet Foundation.

library WitnetCBOR {

  using WitnetBuffer for WitnetBuffer.Buffer;
  using WitnetCBOR for WitnetCBOR.CBOR;

  /// Data struct following the RFC-7049 standard: Concise Binary Object Representation.
  struct CBOR {
      WitnetBuffer.Buffer buffer;
      uint8 initialByte;
      uint8 majorType;
      uint8 additionalInformation;
      uint64 len;
      uint64 tag;
  }

  uint8 internal constant MAJOR_TYPE_INT = 0;
  uint8 internal constant MAJOR_TYPE_NEGATIVE_INT = 1;
  uint8 internal constant MAJOR_TYPE_BYTES = 2;
  uint8 internal constant MAJOR_TYPE_STRING = 3;
  uint8 internal constant MAJOR_TYPE_ARRAY = 4;
  uint8 internal constant MAJOR_TYPE_MAP = 5;
  uint8 internal constant MAJOR_TYPE_TAG = 6;
  uint8 internal constant MAJOR_TYPE_CONTENT_FREE = 7;

  uint32 internal constant UINT32_MAX = type(uint32).max;
  uint64 internal constant UINT64_MAX = type(uint64).max;
  
  error EmptyArray();
  error InvalidLengthEncoding(uint length);
  error UnexpectedMajorType(uint read, uint expected);
  error UnsupportedPrimitive(uint primitive);
  error UnsupportedMajorType(uint unexpected);  

  modifier isMajorType(
      WitnetCBOR.CBOR memory cbor,
      uint8 expected
  ) {
    if (cbor.majorType != expected) {
      revert UnexpectedMajorType(cbor.majorType, expected);
    }
    _;
  }

  modifier notEmpty(WitnetBuffer.Buffer memory buffer) {
    if (buffer.data.length == 0) {
      revert WitnetBuffer.EmptyBuffer();
    }
    _;
  }

  function eof(CBOR memory cbor)
    internal pure
    returns (bool)
  {
    return cbor.buffer.cursor >= cbor.buffer.data.length;
  }

  /// @notice Decode a CBOR structure from raw bytes.
  /// @dev This is the main factory for CBOR instances, which can be later decoded into native EVM types.
  /// @param bytecode Raw bytes representing a CBOR-encoded value.
  /// @return A `CBOR` instance containing a partially decoded value.
  function fromBytes(bytes memory bytecode)
    internal pure
    returns (CBOR memory)
  {
    WitnetBuffer.Buffer memory buffer = WitnetBuffer.Buffer(bytecode, 0);
    return fromBuffer(buffer);
  }

  /// @notice Decode a CBOR structure from raw bytes.
  /// @dev This is an alternate factory for CBOR instances, which can be later decoded into native EVM types.
  /// @param buffer A Buffer structure representing a CBOR-encoded value.
  /// @return A `CBOR` instance containing a partially decoded value.
  function fromBuffer(WitnetBuffer.Buffer memory buffer)
    internal pure
    notEmpty(buffer)
    returns (CBOR memory)
  {
    uint8 initialByte;
    uint8 majorType = 255;
    uint8 additionalInformation;
    uint64 tag = UINT64_MAX;
    uint256 len;
    bool isTagged = true;
    while (isTagged) {
      // Extract basic CBOR properties from input bytes
      initialByte = buffer.readUint8();
      len ++;
      majorType = initialByte >> 5;
      additionalInformation = initialByte & 0x1f;
      // Early CBOR tag parsing.
      if (majorType == MAJOR_TYPE_TAG) {
        uint _cursor = buffer.cursor;
        tag = readLength(buffer, additionalInformation);
        len += buffer.cursor - _cursor;
      } else {
        isTagged = false;
      }
    }
    if (majorType > MAJOR_TYPE_CONTENT_FREE) {
      revert UnsupportedMajorType(majorType);
    }
    return CBOR(
      buffer,
      initialByte,
      majorType,
      additionalInformation,
      uint64(len),
      tag
    );
  }

  function fork(WitnetCBOR.CBOR memory self)
    internal pure
    returns (WitnetCBOR.CBOR memory)
  {
    return CBOR({
      buffer: self.buffer.fork(),
      initialByte: self.initialByte,
      majorType: self.majorType,
      additionalInformation: self.additionalInformation,
      len: self.len,
      tag: self.tag
    });
  }

  function settle(CBOR memory self)
      internal pure
      returns (WitnetCBOR.CBOR memory)
  {
    if (!self.eof()) {
      return fromBuffer(self.buffer);
    } else {
      return self;
    }
  }

  function skip(CBOR memory self)
      internal pure
      returns (WitnetCBOR.CBOR memory)
  {
    if (
      self.majorType == MAJOR_TYPE_INT
        || self.majorType == MAJOR_TYPE_NEGATIVE_INT
        || (
          self.majorType == MAJOR_TYPE_CONTENT_FREE 
            && self.additionalInformation >= 25
            && self.additionalInformation <= 27
        )
    ) {
      self.buffer.cursor += self.peekLength();
    } else if (
        self.majorType == MAJOR_TYPE_STRING
          || self.majorType == MAJOR_TYPE_BYTES
    ) {
      uint64 len = readLength(self.buffer, self.additionalInformation);
      self.buffer.cursor += len;
    } else if (
      self.majorType == MAJOR_TYPE_ARRAY
        || self.majorType == MAJOR_TYPE_MAP
    ) { 
      self.len = readLength(self.buffer, self.additionalInformation);      
    } else if (
       self.majorType != MAJOR_TYPE_CONTENT_FREE
        || (
          self.additionalInformation != 20
            && self.additionalInformation != 21
        )
    ) {
      revert("WitnetCBOR.skip: unsupported major type");
    }
    return self;
  }

  function peekLength(CBOR memory self)
    internal pure
    returns (uint64)
  {
    if (self.additionalInformation < 24) {
      return 0;
    } else if (self.additionalInformation < 28) {
      return uint64(1 << (self.additionalInformation - 24));
    } else {
      revert InvalidLengthEncoding(self.additionalInformation);
    }
  }

  function readArray(CBOR memory self)
    internal pure
    isMajorType(self, MAJOR_TYPE_ARRAY)
    returns (CBOR[] memory items)
  {
    // read array's length and move self cursor forward to the first array element:
    uint64 len = readLength(self.buffer, self.additionalInformation);
    items = new CBOR[](len + 1);
    for (uint ix = 0; ix < len; ix ++) {
      // settle next element in the array:
      self = self.settle();
      // fork it and added to the list of items to be returned:
      items[ix] = self.fork();
      if (self.majorType == MAJOR_TYPE_ARRAY) {
        CBOR[] memory _subitems = self.readArray();
        // move forward to the first element after inner array:
        self = _subitems[_subitems.length - 1];
      } else if (self.majorType == MAJOR_TYPE_MAP) {
        CBOR[] memory _subitems = self.readMap();
        // move forward to the first element after inner map:
        self = _subitems[_subitems.length - 1];
      } else {
        // move forward to the next element:
        self.skip();
      }
    }
    // return self cursor as extra item at the end of the list,
    // as to optimize recursion when jumping over nested arrays:
    items[len] = self;
  }

  function readMap(CBOR memory self)
    internal pure
    isMajorType(self, MAJOR_TYPE_MAP)
    returns (CBOR[] memory items)
  {
    // read number of items within the map and move self cursor forward to the first inner element:
    uint64 len = readLength(self.buffer, self.additionalInformation) * 2;
    items = new CBOR[](len + 1);
    for (uint ix = 0; ix < len; ix ++) {
      // settle next element in the array:
      self = self.settle();
      // fork it and added to the list of items to be returned:
      items[ix] = self.fork();
      if (ix % 2 == 0 && self.majorType != MAJOR_TYPE_STRING) {
        revert UnexpectedMajorType(self.majorType, MAJOR_TYPE_STRING);
      } else if (self.majorType == MAJOR_TYPE_ARRAY || self.majorType == MAJOR_TYPE_MAP) {
        CBOR[] memory _subitems = (self.majorType == MAJOR_TYPE_ARRAY
            ? self.readArray()
            : self.readMap()
        );
        // move forward to the first element after inner array or map:
        self = _subitems[_subitems.length - 1];
      } else {
        // move forward to the next element:
        self.skip();
      }
    }
    // return self cursor as extra item at the end of the list,
    // as to optimize recursion when jumping over nested arrays:
    items[len] = self;
  }

  /// Reads the length of the settle CBOR item from a buffer, consuming a different number of bytes depending on the
  /// value of the `additionalInformation` argument.
  function readLength(
      WitnetBuffer.Buffer memory buffer,
      uint8 additionalInformation
    ) 
    internal pure
    returns (uint64)
  {
    if (additionalInformation < 24) {
      return additionalInformation;
    }
    if (additionalInformation == 24) {
      return buffer.readUint8();
    }
    if (additionalInformation == 25) {
      return buffer.readUint16();
    }
    if (additionalInformation == 26) {
      return buffer.readUint32();
    }
    if (additionalInformation == 27) {
      return buffer.readUint64();
    }
    if (additionalInformation == 31) {
      return UINT64_MAX;
    }
    revert InvalidLengthEncoding(additionalInformation);
  }

  /// @notice Read a `CBOR` structure into a native `bool` value.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as a `bool` value.
  function readBool(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_CONTENT_FREE)
    returns (bool)
  {
    if (cbor.additionalInformation == 20) {
      return false;
    } else if (cbor.additionalInformation == 21) {
      return true;
    } else {
      revert UnsupportedPrimitive(cbor.additionalInformation);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `bytes` value.
  /// @param cbor An instance of `CBOR`.
  /// @return output The value represented by the input, as a `bytes` value.   
  function readBytes(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_BYTES)
    returns (bytes memory output)
  {
    cbor.len = readLength(
      cbor.buffer,
      cbor.additionalInformation
    );
    if (cbor.len == UINT32_MAX) {
      // These checks look repetitive but the equivalent loop would be more expensive.
      uint32 length = uint32(_readIndefiniteStringLength(
        cbor.buffer,
        cbor.majorType
      ));
      if (length < UINT32_MAX) {
        output = abi.encodePacked(cbor.buffer.read(length));
        length = uint32(_readIndefiniteStringLength(
          cbor.buffer,
          cbor.majorType
        ));
        if (length < UINT32_MAX) {
          output = abi.encodePacked(
            output,
            cbor.buffer.read(length)
          );
        }
      }
    } else {
      return cbor.buffer.read(uint32(cbor.len));
    }
  }

  /// @notice Decode a `CBOR` structure into a `fixed16` value.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 5 decimal orders so as to get a fixed precision of 5 decimal positions, which should be OK for most `fixed16`
  /// use cases. In other words, the output of this method is 10,000 times the actual value, encoded into an `int32`.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as an `int128` value.
  function readFloat16(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_CONTENT_FREE)
    returns (int32)
  {
    if (cbor.additionalInformation == 25) {
      return cbor.buffer.readFloat16();
    } else {
      revert UnsupportedPrimitive(cbor.additionalInformation);
    }
  }

  /// @notice Decode a `CBOR` structure into a `fixed32` value.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 9 decimal orders so as to get a fixed precision of 9 decimal positions, which should be OK for most `fixed64`
  /// use cases. In other words, the output of this method is 10^9 times the actual value, encoded into an `int`.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as an `int` value.
  function readFloat32(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_CONTENT_FREE)
    returns (int)
  {
    if (cbor.additionalInformation == 26) {
      return cbor.buffer.readFloat32();
    } else {
      revert UnsupportedPrimitive(cbor.additionalInformation);
    }
  }

  /// @notice Decode a `CBOR` structure into a `fixed64` value.
  /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values
  /// by 15 decimal orders so as to get a fixed precision of 15 decimal positions, which should be OK for most `fixed64`
  /// use cases. In other words, the output of this method is 10^15 times the actual value, encoded into an `int`.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as an `int` value.
  function readFloat64(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_CONTENT_FREE)
    returns (int)
  {
    if (cbor.additionalInformation == 27) {
      return cbor.buffer.readFloat64();
    } else {
      revert UnsupportedPrimitive(cbor.additionalInformation);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `int128[]` value whose inner values follow the same convention 
  /// @notice as explained in `decodeFixed16`.
  /// @param cbor An instance of `CBOR`.
  function readFloat16Array(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_ARRAY)
    returns (int32[] memory values)
  {
    uint64 length = readLength(cbor.buffer, cbor.additionalInformation);
    if (length < UINT64_MAX) {
      values = new int32[](length);
      for (uint64 i = 0; i < length; ) {
        CBOR memory item = fromBuffer(cbor.buffer);
        values[i] = readFloat16(item);
        unchecked {
          i ++;
        }
      }
    } else {
      revert InvalidLengthEncoding(length);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `int128` value.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as an `int128` value.
  function readInt(CBOR memory cbor)
    internal pure
    returns (int)
  {
    if (cbor.majorType == 1) {
      uint64 _value = readLength(
        cbor.buffer,
        cbor.additionalInformation
      );
      return int(-1) - int(uint(_value));
    } else if (cbor.majorType == 0) {
      // Any `uint64` can be safely casted to `int128`, so this method supports majorType 1 as well so as to have offer
      // a uniform API for positive and negative numbers
      return int(readUint(cbor));
    }
    else {
      revert UnexpectedMajorType(cbor.majorType, 1);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `int[]` value.
  /// @param cbor instance of `CBOR`.
  /// @return array The value represented by the input, as an `int[]` value.
  function readIntArray(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_ARRAY)
    returns (int[] memory array)
  {
    uint64 length = readLength(cbor.buffer, cbor.additionalInformation);
    if (length < UINT64_MAX) {
      array = new int[](length);
      for (uint i = 0; i < length; ) {
        CBOR memory item = fromBuffer(cbor.buffer);
        array[i] = readInt(item);
        unchecked {
          i ++;
        }
      }
    } else {
      revert InvalidLengthEncoding(length);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `string` value.
  /// @param cbor An instance of `CBOR`.
  /// @return text The value represented by the input, as a `string` value.
  function readString(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_STRING)
    returns (string memory text)
  {
    cbor.len = readLength(cbor.buffer, cbor.additionalInformation);
    if (cbor.len == UINT64_MAX) {
      bool _done;
      while (!_done) {
        uint64 length = _readIndefiniteStringLength(
          cbor.buffer,
          cbor.majorType
        );
        if (length < UINT64_MAX) {
          text = string(abi.encodePacked(
            text,
            cbor.buffer.readText(length / 4)
          ));
        } else {
          _done = true;
        }
      }
    } else {
      return string(cbor.buffer.readText(cbor.len));
    }
  }

  /// @notice Decode a `CBOR` structure into a native `string[]` value.
  /// @param cbor An instance of `CBOR`.
  /// @return strings The value represented by the input, as an `string[]` value.
  function readStringArray(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_ARRAY)
    returns (string[] memory strings)
  {
    uint length = readLength(cbor.buffer, cbor.additionalInformation);
    if (length < UINT64_MAX) {
      strings = new string[](length);
      for (uint i = 0; i < length; ) {
        CBOR memory item = fromBuffer(cbor.buffer);
        strings[i] = readString(item);
        unchecked {
          i ++;
        }
      }
    } else {
      revert InvalidLengthEncoding(length);
    }
  }

  /// @notice Decode a `CBOR` structure into a native `uint64` value.
  /// @param cbor An instance of `CBOR`.
  /// @return The value represented by the input, as an `uint64` value.
  function readUint(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_INT)
    returns (uint)
  {
    return readLength(
      cbor.buffer,
      cbor.additionalInformation
    );
  }

  /// @notice Decode a `CBOR` structure into a native `uint64[]` value.
  /// @param cbor An instance of `CBOR`.
  /// @return values The value represented by the input, as an `uint64[]` value.
  function readUintArray(CBOR memory cbor)
    internal pure
    isMajorType(cbor, MAJOR_TYPE_ARRAY)
    returns (uint[] memory values)
  {
    uint64 length = readLength(cbor.buffer, cbor.additionalInformation);
    if (length < UINT64_MAX) {
      values = new uint[](length);
      for (uint ix = 0; ix < length; ) {
        CBOR memory item = fromBuffer(cbor.buffer);
        values[ix] = readUint(item);
        unchecked {
          ix ++;
        }
      }
    } else {
      revert InvalidLengthEncoding(length);
    }
  }  

  /// Read the length of a CBOR indifinite-length item (arrays, maps, byte strings and text) from a buffer, consuming
  /// as many bytes as specified by the first byte.
  function _readIndefiniteStringLength(
      WitnetBuffer.Buffer memory buffer,
      uint8 majorType
    )
    private pure
    returns (uint64 len)
  {
    uint8 initialByte = buffer.readUint8();
    if (initialByte == 0xff) {
      return UINT64_MAX;
    }
    len = readLength(
      buffer,
      initialByte & 0x1f
    );
    if (len >= UINT64_MAX) {
      revert InvalidLengthEncoding(len);
    } else if (majorType != (initialByte >> 5)) {
      revert UnexpectedMajorType((initialByte >> 5), majorType);
    }
  }
 
}

library Witnet {

    using WitnetBuffer for WitnetBuffer.Buffer;
    using WitnetCBOR for WitnetCBOR.CBOR;
    using WitnetCBOR for WitnetCBOR.CBOR[];

    /// Struct containing both request and response data related to every query posted to the Witnet Request Board
    struct Query {
        Request request;
        Response response;
        address from;      // Address from which the request was posted.
    }

    /// Possible status of a Witnet query.
    enum QueryStatus {
        Unknown,
        Posted,
        Reported,
        Deleted
    }

    /// Data kept in EVM-storage for every Request posted to the Witnet Request Board.
    struct Request {
        address addr;       // Address of the IWitnetRequest contract containing Witnet data request raw bytecode.
        bytes32 slaHash;    // Radon SLA hash of the Witnet data request.
        bytes32 radHash;    // Radon radHash of the Witnet data request.
        uint256 gasprice;   // Minimum gas price the DR resolver should pay on the solving tx.
        uint256 reward;     // Escrowed reward to be paid to the DR resolver.
    }

    /// Data kept in EVM-storage containing Witnet-provided response metadata and result.
    struct Response {
        address reporter;       // Address from which the result was reported.
        uint256 timestamp;      // Timestamp of the Witnet-provided result.
        bytes32 drTxHash;       // Hash of the Witnet transaction that solved the queried Data Request.
        bytes   cborBytes;      // Witnet-provided result CBOR-bytes to the queried Data Request.
    }

    /// Data struct containing the Witnet-provided result to a Data Request.
    struct Result {
        bool success;           // Flag stating whether the request could get solved successfully, or not.
        WitnetCBOR.CBOR value;  // Resulting value, in CBOR-serialized bytes.
    }

    /// Final query's result status from a requester's point of view.
    enum ResultStatus {
        Void,
        Awaiting,
        Ready,
        Error
    }

    /// Data struct describing an error when trying to fetch a Witnet-provided result to a Data Request.
    struct ResultError {
        ResultErrorCodes code;
        string reason;
    }

    enum ResultErrorCodes {
        /// 0x00: Unknown error. Something went really bad!
        Unknown, 
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Script format errors =============================================================================================
            /// 0x01: At least one of the source scripts is not a valid CBOR-encoded value.
            SourceScriptNotCBOR, 
            /// 0x02: The CBOR value decoded from a source script is not an Array.
            SourceScriptNotArray,
            /// 0x03: The Array value decoded form a source script is not a valid Data Request.
            SourceScriptNotRADON,
            /// Unallocated
            ScriptFormat0x04, ScriptFormat0x05, ScriptFormat0x06, ScriptFormat0x07, ScriptFormat0x08, ScriptFormat0x09,
            ScriptFormat0x0A, ScriptFormat0x0B, ScriptFormat0x0C, ScriptFormat0x0D, ScriptFormat0x0E, ScriptFormat0x0F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Complexity errors ================================================================================================
            /// 0x10: The request contains too many sources.
            RequestTooManySources,
            /// 0x11: The script contains too many calls.
            ScriptTooManyCalls,
            /// Unallocated
            Complexity0x12, Complexity0x13, Complexity0x14, Complexity0x15, Complexity0x16, Complexity0x17, Complexity0x18,
            Complexity0x19, Complexity0x1A, Complexity0x1B, Complexity0x1C, Complexity0x1D, Complexity0x1E, Complexity0x1F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Operator errors ===================================================================================================
            /// 0x20: The operator does not exist.
            UnsupportedOperator,
            /// Unallocated
            Operator0x21, Operator0x22, Operator0x23, Operator0x24, Operator0x25, Operator0x26, Operator0x27, Operator0x28,
            Operator0x29, Operator0x2A, Operator0x2B, Operator0x2C, Operator0x2D, Operator0x2E, Operator0x2F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Retrieval-specific errors =========================================================================================
            /// 0x30: At least one of the sources could not be retrieved, but returned HTTP error.
            HTTP,
            /// 0x31: Retrieval of at least one of the sources timed out.
            RetrievalTimeout,
            /// Unallocated
            Retrieval0x32, Retrieval0x33, Retrieval0x34, Retrieval0x35, Retrieval0x36, Retrieval0x37, Retrieval0x38, 
            Retrieval0x39, Retrieval0x3A, Retrieval0x3B, Retrieval0x3C, Retrieval0x3D, Retrieval0x3E, Retrieval0x3F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Math errors =======================================================================================================
            /// 0x40: Math operator caused an underflow.
            Underflow,
            /// 0x41: Math operator caused an overflow.
            Overflow,
            /// 0x42: Tried to divide by zero.
            DivisionByZero,
            /// Unallocated
            Math0x43, Math0x44, Math0x45, Math0x46, Math0x47, Math0x48, Math0x49, 
            Math0x4A, Math0x4B, Math0x4C, Math0x4D, Math0x4E, Math0x4F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Other errors ======================================================================================================
            /// 0x50: Received zero reveals
            NoReveals,
            /// 0x51: Insufficient consensus in tally precondition clause
            InsufficientConsensus,
            /// 0x52: Received zero commits
            InsufficientCommits,
            /// 0x53: Generic error during tally execution
            TallyExecution,
            /// Unallocated
            OtherError0x54, OtherError0x55, OtherError0x56, OtherError0x57, OtherError0x58, OtherError0x59,
            OtherError0x5A, OtherError0x5B, OtherError0x5C, OtherError0x5D, OtherError0x5E, OtherError0x5F,
            /// 0x60: Invalid reveal serialization (malformed reveals are converted to this value)
            MalformedReveal,
            /// Unallocated
            OtherError0x61, OtherError0x62, OtherError0x63, OtherError0x64, OtherError0x65, OtherError0x66,
            OtherError0x67, OtherError0x68, OtherError0x69, OtherError0x6A, OtherError0x6B, OtherError0x6C,
            OtherError0x6D, OtherError0x6E,OtherError0x6F,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Access errors =====================================================================================================
            /// 0x70: Tried to access a value from an array using an index that is out of bounds
            ArrayIndexOutOfBounds,
            /// 0x71: Tried to access a value from a map using a key that does not exist
            MapKeyNotFound,
            /// Unallocated
            OtherError0x72, OtherError0x73, OtherError0x74, OtherError0x75, OtherError0x76, OtherError0x77, OtherError0x78, 
            OtherError0x79, OtherError0x7A, OtherError0x7B, OtherError0x7C, OtherError0x7D, OtherError0x7E, OtherError0x7F, 
            OtherError0x80, OtherError0x81, OtherError0x82, OtherError0x83, OtherError0x84, OtherError0x85, OtherError0x86, 
            OtherError0x87, OtherError0x88, OtherError0x89, OtherError0x8A, OtherError0x8B, OtherError0x8C, OtherError0x8D, 
            OtherError0x8E, OtherError0x8F, OtherError0x90, OtherError0x91, OtherError0x92, OtherError0x93, OtherError0x94, 
            OtherError0x95, OtherError0x96, OtherError0x97, OtherError0x98, OtherError0x99, OtherError0x9A, OtherError0x9B,
            OtherError0x9C, OtherError0x9D, OtherError0x9E, OtherError0x9F, OtherError0xA0, OtherError0xA1, OtherError0xA2, 
            OtherError0xA3, OtherError0xA4, OtherError0xA5, OtherError0xA6, OtherError0xA7, OtherError0xA8, OtherError0xA9, 
            OtherError0xAA, OtherError0xAB, OtherError0xAC, OtherError0xAD, OtherError0xAE, OtherError0xAF, OtherError0xB0,
            OtherError0xB1, OtherError0xB2, OtherError0xB3, OtherError0xB4, OtherError0xB5, OtherError0xB6, OtherError0xB7,
            OtherError0xB8, OtherError0xB9, OtherError0xBA, OtherError0xBB, OtherError0xBC, OtherError0xBD, OtherError0xBE,
            OtherError0xBF, OtherError0xC0, OtherError0xC1, OtherError0xC2, OtherError0xC3, OtherError0xC4, OtherError0xC5,
            OtherError0xC6, OtherError0xC7, OtherError0xC8, OtherError0xC9, OtherError0xCA, OtherError0xCB, OtherError0xCC,
            OtherError0xCD, OtherError0xCE, OtherError0xCF, OtherError0xD0, OtherError0xD1, OtherError0xD2, OtherError0xD3,
            OtherError0xD4, OtherError0xD5, OtherError0xD6, OtherError0xD7, OtherError0xD8, OtherError0xD9, OtherError0xDA,
            OtherError0xDB, OtherError0xDC, OtherError0xDD, OtherError0xDE, OtherError0xDF,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// Bridge errors: errors that only belong in inter-client communication ==============================================
            /// 0xE0: Requests that cannot be parsed must always get this error as their result.
            /// However, this is not a valid result in a Tally transaction, because invalid requests
            /// are never included into blocks and therefore never get a Tally in response.
            BridgeMalformedRequest,
            /// 0xE1: Witnesses exceeds 100
            BridgePoorIncentives,
            /// 0xE2: The request is rejected on the grounds that it may cause the submitter to spend or stake an
            /// amount of value that is unjustifiably high when compared with the reward they will be getting
            BridgeOversizedResult,
            /// Unallocated
            OtherError0xE3, OtherError0xE4, OtherError0xE5, OtherError0xE6, OtherError0xE7, OtherError0xE8, OtherError0xE9,
            OtherError0xEA, OtherError0xEB, OtherError0xEC, OtherError0xED, OtherError0xEE, OtherError0xEF, OtherError0xF0,
            OtherError0xF1, OtherError0xF2, OtherError0xF3, OtherError0xF4, OtherError0xF5, OtherError0xF6, OtherError0xF7,
            OtherError0xF8, OtherError0xF9, OtherError0xFA, OtherError0xFB, OtherError0xFC, OtherError0xFD, OtherError0xFE,
        ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
        /// 0xFF: Some tally error is not intercepted but should
        UnhandledIntercept
    }


    /// ===============================================================================================================
    /// --- 'Witnet.Result' helper methods ----------------------------------------------------------------------------

    modifier _isError(Result memory result) {
        require(!result.success, "Witnet: no actual errors");
        _;
    }

    modifier _isReady(Result memory result) {
        require(result.success, "Witnet: tried to decode value from errored result.");
        _;
    }

    /// @dev Decode an address from the Witnet.Result's CBOR value.
    function asAddress(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (address)
    {
        if (result.value.majorType == uint8(WitnetCBOR.MAJOR_TYPE_BYTES)) {
            return toAddress(result.value.readBytes());
        } else {
            // TODO
            revert("WitnetLib: reading address from string not yet supported.");
        }
    }

    /// @dev Decode a `bool` value from the Witnet.Result's CBOR value.
    function asBool(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (bool)
    {
        return result.value.readBool();
    }

    /// @dev Decode a `bytes` value from the Witnet.Result's CBOR value.
    function asBytes(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns(bytes memory)
    {
        return result.value.readBytes();
    }

    /// @dev Decode a `bytes4` value from the Witnet.Result's CBOR value.
    function asBytes4(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (bytes4)
    {
        return toBytes4(asBytes(result));
    }

    /// @dev Decode a `bytes32` value from the Witnet.Result's CBOR value.
    function asBytes32(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (bytes32)
    {
        return toBytes32(asBytes(result));
    }

    /// @notice Returns the Witnet.Result's unread CBOR value.
    function asCborValue(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (WitnetCBOR.CBOR memory)
    {
        return result.value;
    }

    /// @notice Decode array of CBOR values from the Witnet.Result's CBOR value. 
    function asCborArray(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (WitnetCBOR.CBOR[] memory)
    {
        return result.value.readArray();
    }

    /// @dev Decode a fixed16 (half-precision) numeric value from the Witnet.Result's CBOR value.
    /// @dev Due to the lack of support for floating or fixed point arithmetic in the EVM, this method offsets all values.
    /// by 5 decimal orders so as to get a fixed precision of 5 decimal positions, which should be OK for most `fixed16`.
    /// use cases. In other words, the output of this method is 10,000 times the actual value, encoded into an `int32`.
    function asFixed16(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (int32)
    {
        return result.value.readFloat16();
    }

    /// @dev Decode an array of fixed16 values from the Witnet.Result's CBOR value.
    function asFixed16Array(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (int32[] memory)
    {
        return result.value.readFloat16Array();
    }

    /// @dev Decode an `int64` value from the Witnet.Result's CBOR value.
    function asInt(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (int)
    {
        return result.value.readInt();
    }

    /// @dev Decode an array of integer numeric values from a Witnet.Result as an `int[]` array.
    /// @param result An instance of Witnet.Result.
    /// @return The `int[]` decoded from the Witnet.Result.
    function asIntArray(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (int[] memory)
    {
        return result.value.readIntArray();
    }

    /// @dev Decode a `string` value from the Witnet.Result's CBOR value.
    /// @param result An instance of Witnet.Result.
    /// @return The `string` decoded from the Witnet.Result.
    function asText(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns(string memory)
    {
        return result.value.readString();
    }

    /// @dev Decode an array of strings from the Witnet.Result's CBOR value.
    /// @param result An instance of Witnet.Result.
    /// @return The `string[]` decoded from the Witnet.Result.
    function asTextArray(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (string[] memory)
    {
        return result.value.readStringArray();
    }

    /// @dev Decode a `uint64` value from the Witnet.Result's CBOR value.
    /// @param result An instance of Witnet.Result.
    /// @return The `uint` decoded from the Witnet.Result.
    function asUint(Witnet.Result memory result)
        internal pure
        _isReady(result)
        returns (uint)
    {
        return result.value.readUint();
    }

    /// @dev Decode an array of `uint64` values from the Witnet.Result's CBOR value.
    /// @param result An instance of Witnet.Result.
    /// @return The `uint[]` decoded from the Witnet.Result.
    function asUintArray(Witnet.Result memory result)
        internal pure
        returns (uint[] memory)
    {
        return result.value.readUintArray();
    }


    /// ===============================================================================================================
    /// --- 'bytes' helper methods ------------------------------------------------------------------------------------

    /// @dev Transform given bytes into a Witnet.Result instance.
    /// @param bytecode Raw bytes representing a CBOR-encoded value.
    /// @return A `Witnet.Result` instance.
    function resultFromCborBytes(bytes memory bytecode)
        internal pure
        returns (Witnet.Result memory)
    {
        WitnetCBOR.CBOR memory cborValue = WitnetCBOR.fromBytes(bytecode);
        return _resultFromCborValue(cborValue);
    }

    function toAddress(bytes memory _value) internal pure returns (address) {
        return address(toBytes20(_value));
    }

    function toBytes4(bytes memory _value) internal pure returns (bytes4) {
        return bytes4(toFixedBytes(_value, 4));
    }
    
    function toBytes20(bytes memory _value) internal pure returns (bytes20) {
        return bytes20(toFixedBytes(_value, 20));
    }
    
    function toBytes32(bytes memory _value) internal pure returns (bytes32) {
        return toFixedBytes(_value, 32);
    }

    function toFixedBytes(bytes memory _value, uint8 _numBytes)
        internal pure
        returns (bytes32 _bytes32)
    {
        assert(_numBytes <= 32);
        unchecked {
            uint _len = _value.length > _numBytes ? _numBytes : _value.length;
            for (uint _i = 0; _i < _len; _i ++) {
                _bytes32 |= bytes32(_value[_i] & 0xff) >> (_i * 8);
            }
        }
    }


    /// ===============================================================================================================
    /// --- 'string' helper methods -----------------------------------------------------------------------------------

    function toLowerCase(string memory str)
        internal pure
        returns (string memory)
    {
        bytes memory lowered = new bytes(bytes(str).length);
        unchecked {
            for (uint i = 0; i < lowered.length; i ++) {
                uint8 char = uint8(bytes(str)[i]);
                if (char >= 65 && char <= 90) {
                    lowered[i] = bytes1(char + 32);
                } else {
                    lowered[i] = bytes1(char);
                }
            }
        }
        return string(lowered);
    }

    /// @notice Converts bytes32 into string.
    function toString(bytes32 _bytes32)
        internal pure
        returns (string memory)
    {
        bytes memory _bytes = new bytes(_toStringLength(_bytes32));
        for (uint _i = 0; _i < _bytes.length;) {
            _bytes[_i] = _bytes32[_i];
            unchecked {
                _i ++;
            }
        }
        return string(_bytes);
    }

    function tryUint(string memory str)
        internal pure
        returns (uint res, bool)
    {
        unchecked {
            for (uint256 i = 0; i < bytes(str).length; i++) {
                if (
                    (uint8(bytes(str)[i]) - 48) < 0
                        || (uint8(bytes(str)[i]) - 48) > 9
                ) {
                    return (0, false);
                }
                res += (uint8(bytes(str)[i]) - 48) * 10 ** (bytes(str).length - i - 1);
            }
            return (res, true);
        }
    }


    /// ===============================================================================================================
    /// --- 'uint8' helper methods ------------------------------------------------------------------------------------

    /// @notice Convert a `uint8` into a 2 characters long `string` representing its two less significant hexadecimal values.
    function toHexString(uint8 _u)
        internal pure
        returns (string memory)
    {
        bytes memory b2 = new bytes(2);
        uint8 d0 = uint8(_u / 16) + 48;
        uint8 d1 = uint8(_u % 16) + 48;
        if (d0 > 57)
            d0 += 7;
        if (d1 > 57)
            d1 += 7;
        b2[0] = bytes1(d0);
        b2[1] = bytes1(d1);
        return string(b2);
    }

    /// @notice Convert a `uint8` into a 1, 2 or 3 characters long `string` representing its.
    /// three less significant decimal values.
    function toString(uint8 _u)
        internal pure
        returns (string memory)
    {
        if (_u < 10) {
            bytes memory b1 = new bytes(1);
            b1[0] = bytes1(uint8(_u) + 48);
            return string(b1);
        } else if (_u < 100) {
            bytes memory b2 = new bytes(2);
            b2[0] = bytes1(uint8(_u / 10) + 48);
            b2[1] = bytes1(uint8(_u % 10) + 48);
            return string(b2);
        } else {
            bytes memory b3 = new bytes(3);
            b3[0] = bytes1(uint8(_u / 100) + 48);
            b3[1] = bytes1(uint8(_u % 100 / 10) + 48);
            b3[2] = bytes1(uint8(_u % 10) + 48);
            return string(b3);
        }
    }

    /// @notice Convert a `uint` into a string` representing its value.
    function toString(uint v)
        internal pure 
        returns (string memory)
    {
        uint maxlength = 100;
        bytes memory reversed = new bytes(maxlength);
        uint i = 0;
        do {
            uint8 remainder = uint8(v % 10);
            v = v / 10;
            reversed[i ++] = bytes1(48 + remainder);
        } while (v != 0);
        bytes memory buf = new bytes(i);
        for (uint j = 1; j <= i; j ++) {
            buf[j - 1] = reversed[i - j];
        }
        return string(buf);
    }


    /// ===============================================================================================================
    /// --- Witnet library private methods ----------------------------------------------------------------------------

    /// @dev Decode a CBOR value into a Witnet.Result instance.
    function _resultFromCborValue(WitnetCBOR.CBOR memory cbor)
        private pure
        returns (Witnet.Result memory)    
    {
        // Witnet uses CBOR tag 39 to represent RADON error code identifiers.
        // [CBOR tag 39] Identifiers for CBOR: https://github.com/lucas-clemente/cbor-specs/blob/master/id.md
        bool success = cbor.tag != 39;
        return Witnet.Result(success, cbor);
    }

    /// @dev Calculate length of string-equivalent to given bytes32.
    function _toStringLength(bytes32 _bytes32)
        private pure
        returns (uint _length)
    {
        for (; _length < 32; ) {
            if (_bytes32[_length] == 0) {
                break;
            }
            unchecked {
                _length ++;
            }
        }
    }
}

library WitnetV2 {

    error IndexOutOfBounds(uint256 index, uint256 range);
    error InsufficientBalance(uint256 weiBalance, uint256 weiExpected);
    error InsufficientFee(uint256 weiProvided, uint256 weiExpected);
    error Unauthorized(address violator);

    error RadonFilterMissingArgs(uint8 opcode);

    error RadonRequestNoSources();
    error RadonRequestSourcesArgsMismatch(uint expected, uint actual);
    error RadonRequestMissingArgs(uint index, uint expected, uint actual);
    error RadonRequestResultsMismatch(uint index, uint8 read, uint8 expected);
    error RadonRequestTooHeavy(bytes bytecode, uint weight);

    error RadonSlaNoReward();
    error RadonSlaNoWitnesses();
    error RadonSlaTooManyWitnesses(uint256 numWitnesses);
    error RadonSlaConsensusOutOfRange(uint256 percentage);
    error RadonSlaLowCollateral(uint256 witnessCollateral);

    error UnsupportedDataRequestMethod(uint8 method, string schema, string body, string[2][] headers);
    error UnsupportedRadonDataType(uint8 datatype, uint256 maxlength);
    error UnsupportedRadonFilterOpcode(uint8 opcode);
    error UnsupportedRadonFilterArgs(uint8 opcode, bytes args);
    error UnsupportedRadonReducerOpcode(uint8 opcode);
    error UnsupportedRadonReducerScript(uint8 opcode, bytes script, uint256 offset);
    error UnsupportedRadonScript(bytes script, uint256 offset);
    error UnsupportedRadonScriptOpcode(bytes script, uint256 cursor, uint8 opcode);
    error UnsupportedRadonTallyScript(bytes32 hash);

    function toEpoch(uint _timestamp) internal pure returns (uint) {
        return 1 + (_timestamp - 11111) / 15;
    }

    function toTimestamp(uint _epoch) internal pure returns (uint) {
        return 111111+ _epoch * 15;
    }

    struct Beacon {
        uint256 escrow;
        uint256 evmBlock;
        uint256 gasprice;
        address relayer;
        address slasher;
        uint256 superblockIndex;
        uint256 superblockRoot;        
    }

    enum BeaconStatus {
        Idle
    }

    struct Block {
        bytes32 blockHash;
        bytes32 drTxsRoot;
        bytes32 drTallyTxsRoot;
    }
    
    enum BlockStatus {
        Idle
    }

    struct DrPost {
        uint256 block;
        DrPostStatus status;
        DrPostRequest request;
        DrPostResponse response;
    }
    
    /// Data kept in EVM-storage for every Request posted to the Witnet Request Board.
    struct DrPostRequest {
        uint256 epoch;
        address requester;
        address reporter;
        bytes32 radHash;
        bytes32 slaHash;
        uint256 weiReward;
    }

    /// Data kept in EVM-storage containing Witnet-provided response metadata and result.
    struct DrPostResponse {
        address disputer;
        address reporter;
        uint256 escrowed;
        uint256 drCommitTxEpoch;
        uint256 drTallyTxEpoch;
        bytes32 drTallyTxHash;
        bytes   drTallyResultCborBytes;
    }

    enum DrPostStatus {
        Void,
        Deleted,
        Expired,
        Posted,
        Disputed,
        Reported,
        Finalized,
        Accepted,
        Rejected
    }

    struct DataProvider {
        string  authority;
        uint256 totalEndpoints;
        mapping (uint256 => bytes32) endpoints;
    }

    enum DataRequestMethods {
        /* 0 */ Unknown,
        /* 1 */ HttpGet,
        /* 2 */ Rng,
        /* 3 */ HttpPost
    }

    enum RadonDataTypes {
        /* 0x00 */ Any, 
        /* 0x01 */ Array,
        /* 0x02 */ Bool,
        /* 0x03 */ Bytes,
        /* 0x04 */ Integer,
        /* 0x05 */ Float,
        /* 0x06 */ Map,
        /* 0x07 */ String,
        Unused0x08, Unused0x09, Unused0x0A, Unused0x0B,
        Unused0x0C, Unused0x0D, Unused0x0E, Unused0x0F,
        /* 0x10 */ Same,
        /* 0x11 */ Inner,
        /* 0x12 */ Match,
        /* 0x13 */ Subscript
    }

    struct RadonFilter {
        RadonFilterOpcodes opcode;
        bytes args;
    }

    enum RadonFilterOpcodes {
        /* 0x00 */ GreaterThan,
        /* 0x01 */ LessThan,
        /* 0x02 */ Equals,
        /* 0x03 */ AbsoluteDeviation,
        /* 0x04 */ RelativeDeviation,
        /* 0x05 */ StandardDeviation,
        /* 0x06 */ Top,
        /* 0x07 */ Bottom,
        /* 0x08 */ Mode,
        /* 0x09 */ LessOrEqualThan
    }

    struct RadonReducer {
        RadonReducerOpcodes opcode;
        RadonFilter[] filters;
        bytes script;
    }

    enum RadonReducerOpcodes {
        /* 0x00 */ Minimum,
        /* 0x01 */ Maximum,
        /* 0x02 */ Mode,
        /* 0x03 */ AverageMean,
        /* 0x04 */ AverageMeanWeighted,
        /* 0x05 */ AverageMedian,
        /* 0x06 */ AverageMedianWeighted,
        /* 0x07 */ StandardDeviation,
        /* 0x08 */ AverageDeviation,
        /* 0x09 */ MedianDeviation,
        /* 0x0A */ MaximumDeviation,
        /* 0x0B */ ConcatenateAndHash
    }

    struct RadonRetrieval {
        uint8 argsCount;
        DataRequestMethods method;
        RadonDataTypes resultDataType;
        string url;
        string body;
        string[2][] headers;
        bytes script;
    }

    struct RadonSLA {
        uint numWitnesses;
        uint minConsensusPercentage;
        uint witnessReward;
        uint witnessCollateral;
        uint minerCommitRevealFee;
    }

    /// @notice Returns `true` if all witnessing parameters in `b` have same
    /// @notice value or greater than the ones in `a`.
    function equalOrGreaterThan(RadonSLA memory a, RadonSLA memory b)
        internal pure
        returns (bool)
    {
        return (
            a.numWitnesses >= b.numWitnesses
                && a.minConsensusPercentage >= b.minConsensusPercentage
                && a.witnessReward >= b.witnessReward
                && a.witnessCollateral >= b.witnessCollateral
                && a.minerCommitRevealFee >= b.minerCommitRevealFee
        );
    }

}

interface IWitnetPriceSolver {
    struct Price {
        uint value;
        uint timestamp;
        bytes32 drTxHash;
        Witnet.ResultStatus status;
    }
    function class() external pure returns (bytes4);
    function delegator() external view returns (address);
    function solve(bytes4 feedId) external view returns (Price memory);
    function validate(bytes4 feedId, string[] calldata initdata) external;
}

interface IWitnetPriceFeeds {   
    /// ======================================================================================================
    /// --- IFeeds extension ---------------------------------------------------------------------------------
    
    function lookupDecimals(bytes4 feedId) external view returns (uint8);    
    function lookupPriceSolver(bytes4 feedId) external view returns (
            IWitnetPriceSolver solverAddress, 
            string[] memory solverDeps
        );

    /// ======================================================================================================
    /// --- IWitnetFeeds extension ---------------------------------------------------------------------------

    function latestPrice(bytes4 feedId) external view returns (IWitnetPriceSolver.Price memory);
    function latestPrices(bytes4[] calldata feedIds)  external view returns (IWitnetPriceSolver.Price[] memory);
}

interface IWitnetPriceSolverDeployer {
    event WitnetPriceSolverDeployed(address indexed from, address solver, bytes32 codehash, bytes constructorParams);
    function deployPriceSolver(bytes calldata initcode, bytes calldata additionalParams) external returns (address);
    function determinePriceSolverAddress(bytes calldata initcode, bytes calldata additionalParams) external view returns (address);
}

interface IFeeds {
    function hash(string calldata caption) external pure returns (bytes4);
    function lookupCaption(bytes4) external view returns (string memory);
    function supportedFeeds() external view returns (bytes4[] memory, string[] memory, bytes32[] memory);
    function supportsCaption(string calldata) external view returns (bool);
    function totalFeeds() external view returns (uint256);
}

interface IWitnetBytecodes {

    function bytecodeOf(bytes32 radHash) external view returns (bytes memory);
    function bytecodeOf(bytes32 radHash, bytes32 slahHash) external view returns (bytes memory);

    function hashOf(
            bytes32[] calldata sources,
            bytes32 aggregator,
            bytes32 tally,
            uint16 resultMaxSize,
            string[][] calldata args
        ) external pure returns (bytes32);
    function hashOf(bytes32 radHash, bytes32 slaHash) external pure returns (bytes32 drQueryHash);
    function hashWeightWitsOf(bytes32 radHash, bytes32 slaHash) external view returns (
            bytes32 drQueryHash,
            uint32  drQueryWeight,
            uint256 drQueryWits
        );

    function lookupDataProvider(uint256 index) external view returns (string memory, uint);
    function lookupDataProviderIndex(string calldata authority) external view returns (uint);
    function lookupDataProviderSources(uint256 index, uint256 offset, uint256 length) external view returns (bytes32[] memory);

    function lookupRadonReducer(bytes32 hash) external view returns (WitnetV2.RadonReducer memory);
    
    function lookupRadonRetrieval(bytes32 hash) external view returns (WitnetV2.RadonRetrieval memory);
    function lookupRadonRetrievalArgsCount(bytes32 hash) external view returns (uint8);
    function lookupRadonRetrievalResultDataType(bytes32 hash) external view returns (WitnetV2.RadonDataTypes);
    
    function lookupRadonRequestAggregator(bytes32 radHash) external view returns (WitnetV2.RadonReducer memory);
    function lookupRadonRequestResultMaxSize(bytes32 radHash) external view returns (uint256);
    function lookupRadonRequestResultDataType(bytes32 radHash) external view returns (WitnetV2.RadonDataTypes);
    function lookupRadonRequestSources(bytes32 radHash) external view returns (bytes32[] memory);
    function lookupRadonRequestSourcesCount(bytes32 radHash) external view returns (uint);
    function lookupRadonRequestTally(bytes32 radHash) external view returns (WitnetV2.RadonReducer memory);
    
    function lookupRadonSLA(bytes32 slaHash) external view returns (WitnetV2.RadonSLA memory);
    function lookupRadonSLAReward(bytes32 slaHash) external view returns (uint);
    
    function verifyRadonRetrieval(
            WitnetV2.DataRequestMethods requestMethod,
            string calldata requestSchema,
            string calldata requestAuthority,
            string calldata requestPath,
            string calldata requestQuery,
            string calldata requestBody,
            string[2][] calldata requestHeaders,
            bytes calldata requestRadonScript
        ) external returns (bytes32 hash);
    
    function verifyRadonReducer(WitnetV2.RadonReducer calldata reducer)
        external returns (bytes32 hash);
    
    function verifyRadonRequest(
            bytes32[] calldata sources,
            bytes32 aggregator,
            bytes32 tally,
            uint16 resultMaxSize,
            string[][] calldata args
        ) external returns (bytes32 radHash);
    
    function verifyRadonSLA(WitnetV2.RadonSLA calldata sla)
        external returns (bytes32 slaHash);

    function totalDataProviders() external view returns (uint);
   
}

interface IWitnetBytecodesErrors {
    error UnknownRadonRetrieval(bytes32 hash);
    error UnknownRadonReducer(bytes32 hash);
    error UnknownRadonRequest(bytes32 hash);
    error UnknownRadonSLA(bytes32 hash);  
}

interface IWitnetBytecodesEvents {    
    event NewDataProvider(uint256 index);
    event NewRadonRetrievalHash(bytes32 hash);
    event NewRadonReducerHash(bytes32 hash);
    event NewRadHash(bytes32 hash);
    event NewSlaHash(bytes32 hash);
}

abstract contract WitnetBytecodes
    is
        IWitnetBytecodes,
        IWitnetBytecodesErrors,
        IWitnetBytecodesEvents
{}

interface IWitnetRequestFactory {
    event WitnetRequestTemplateBuilt(address template, bool parameterized);
    function buildRequestTemplate(
            bytes32[] memory sourcesIds,
            bytes32 aggregatorId,
            bytes32 tallyId,
            uint16  resultDataMaxSize
        ) external returns (address template);
    function class() external view returns (bytes4);    
    function registry() external view returns (WitnetBytecodes);
}

abstract contract WitnetRequestFactory
    is
        IWitnetRequestFactory
{}

/// @title Witnet Request Board emitting events interface.
/// @author The Witnet Foundation.
interface IWitnetRequestBoardEvents {
    
    /// Emitted when a Witnet Data Request is posted to the WRB.
    event PostedRequest(uint256 queryId, address from);

    /// Emitted when a Witnet-solved result is reported to the WRB.
    event PostedResult(uint256 queryId, address from);

    /// Emitted when all data related to given query is deleted from the WRB.
    event DeletedQuery(uint256 queryId, address from);
}

/// @title The Witnet Request Board Reporter interface.
/// @author The Witnet Foundation.
interface IWitnetRequestBoardReporter {

    /// @notice Reports the Witnet-provided result to a previously posted request. 
    /// @dev Will assume `block.timestamp` as the timestamp at which the request was solved.
    /// @dev Fails if:
    /// @dev - the `_queryId` is not in 'Posted' status.
    /// @dev - provided `_drTxHash` is zero;
    /// @dev - length of provided `_result` is zero.
    /// @param _queryId The unique identifier of the data request.
    /// @param _drTxHash The hash of the corresponding data request transaction in Witnet.
    /// @param _result The result itself as bytes.
    function reportResult(
            uint256 _queryId,
            bytes32 _drTxHash,
            bytes calldata _result
        ) external;

    /// @notice Reports the Witnet-provided result to a previously posted request.
    /// @dev Fails if:
    /// @dev - called from unauthorized address;
    /// @dev - the `_queryId` is not in 'Posted' status.
    /// @dev - provided `_drTxHash` is zero;
    /// @dev - length of provided `_result` is zero.
    /// @param _queryId The unique query identifier
    /// @param _timestamp The timestamp of the solving tally transaction in Witnet.
    /// @param _drTxHash The hash of the corresponding data request transaction in Witnet.
    /// @param _result The result itself as bytes.
    function reportResult(
            uint256 _queryId,
            uint256 _timestamp,
            bytes32 _drTxHash,
            bytes calldata _result
        ) external;

    /// @notice Reports Witnet-provided results to multiple requests within a single EVM tx.
    /// @dev Must emit a PostedResult event for every succesfully reported result.
    /// @param _batchResults Array of BatchResult structs, every one containing:
    ///         - unique query identifier;
    ///         - timestamp of the solving tally txs in Witnet. If zero is provided, EVM-timestamp will be used instead;
    ///         - hash of the corresponding data request tx at the Witnet side-chain level;
    ///         - data request result in raw bytes.
    /// @param _verbose If true, must emit a BatchReportError event for every failing report, if any. 
    function reportResultBatch(BatchResult[] calldata _batchResults, bool _verbose) external;
        
        struct BatchResult {
            uint256 queryId;
            uint256 timestamp;
            bytes32 drTxHash;
            bytes   cborBytes;
        }

        event BatchReportError(uint256 queryId, string reason);
}

/// @title Witnet Requestor Interface
/// @notice It defines how to interact with the Witnet Request Board in order to:
///   - request the execution of Witnet Radon scripts (data request);
///   - upgrade the resolution reward of any previously posted request, in case gas price raises in mainnet;
///   - read the result of any previously posted request, eventually reported by the Witnet DON.
///   - remove from storage all data related to past and solved data requests, and results.
/// @author The Witnet Foundation.
interface IWitnetRequestBoardRequestor {

    /// @notice Returns query's result current status from a requester's point of view:
    /// @notice   - 0 => Void: the query is either non-existent or deleted;
    /// @notice   - 1 => Awaiting: the query has not yet been reported;
    /// @notice   - 2 => Ready: the query has been succesfully solved;
    /// @notice   - 3 => Error: the query couldn't get solved due to some issue.
    /// @param _queryId The unique query identifier.
    function checkResultStatus(uint256 _queryId) external view returns (Witnet.ResultStatus);

    /// @notice Gets error code identifying some possible failure on the resolution of the given query.
    /// @param _queryId The unique query identifier.
    function checkResultError(uint256 _queryId) external view returns (Witnet.ResultError memory);

    /// @notice Retrieves a copy of all Witnet-provided data related to a previously posted request, removing the whole query from the WRB storage.
    /// @dev Fails if the `_queryId` is not in 'Reported' status, or called from an address different to
    /// @dev the one that actually posted the given request.
    /// @param _queryId The unique query identifier.
    function deleteQuery(uint256 _queryId) external returns (Witnet.Response memory);

    /// @notice Requests the execution of the given Witnet Data Request in expectation that it will be relayed and solved by the Witnet DON.
    /// @notice A reward amount is escrowed by the Witnet Request Board that will be transferred to the reporter who relays back the Witnet-provided 
    /// @notice result to this request.
    /// @dev Fails if:
    /// @dev - provided reward is too low.
    /// @dev - provided script is zero address.
    /// @dev - provided script bytecode is empty.
    /// @param addr The address of the IWitnetRequest contract that can provide the actual Data Request bytecode.
    /// @return _queryId Unique query identifier.
    function postRequest(IWitnetRequest addr) external payable returns (uint256 _queryId);

    /// @notice Requests the execution of the given Witnet Data Request in expectation that it will be relayed and solved by the Witnet DON.
    /// @notice A reward amount is escrowed by the Witnet Request Board that will be transferred to the reporter who relays back the Witnet-provided 
    /// @notice result to this request.
    /// @dev Fails if, provided reward is too low.
    /// @param radHash The RAD hash of the data request to be solved by Witnet.
    /// @param slaHash The SLA hash of the data request to be solved by Witnet.
    /// @return _queryId Unique query identifier.
    function postRequest(bytes32 radHash, bytes32 slaHash) external payable returns (uint256 _queryId);

    /// @notice Requests the execution of the given Witnet Data Request in expectation that it will be relayed and solved by the Witnet DON.
    /// @notice A reward amount is escrowed by the Witnet Request Board that will be transferred to the reporter who relays back the Witnet-provided 
    /// @notice result to this request.
    /// @dev Fails if, provided reward is too low.
    /// @param radHash The RAD hash of the data request to be solved by Witnet.
    /// @param slaParams The SLA params of the data request to be solved by Witnet.
    /// @return _queryId Unique query identifier.
    function postRequest(bytes32 radHash, WitnetV2.RadonSLA calldata slaParams) external payable returns (uint256 _queryId);

    /// @notice Increments the reward of a previously posted request by adding the transaction value to it.
    /// @dev Updates request `gasPrice` in case this method is called with a higher 
    /// @dev gas price value than the one used in previous calls to `postRequest` or
    /// @dev `upgradeReward`. 
    /// @dev Fails if the `_queryId` is not in 'Posted' status.
    /// @dev Fails also in case the request `gasPrice` is increased, and the new 
    /// @dev reward value gets below new recalculated threshold. 
    /// @param _queryId The unique query identifier.
    function upgradeReward(uint256 _queryId) external payable;
}

/// @title Witnet Request Board info interface.
/// @author The Witnet Foundation.
interface IWitnetRequestBoardView {

    /// @notice Estimates the amount of reward we need to insert for a given gas price.
    /// @param _gasPrice The gas price for which we need to calculate the rewards.
    function estimateReward(uint256 _gasPrice) external view returns (uint256);

    /// @notice Returns next query id to be generated by the Witnet Request Board.
    function getNextQueryId() external view returns (uint256);

    /// @notice Gets the whole Query data contents, if any, no matter its current status.
    function getQueryData(uint256 _queryId) external view returns (Witnet.Query memory);

    /// @notice Gets current status of given query.
    function getQueryStatus(uint256 _queryId) external view returns (Witnet.QueryStatus);

    /// @notice Retrieves the whole Request record posted to the Witnet Request Board.
    /// @dev Fails if the `_queryId` is not valid or, if it has already been reported
    /// @dev or deleted.
    /// @param _queryId The unique identifier of a previously posted query.
    function readRequest(uint256 _queryId) external view returns (Witnet.Request memory);

    /// @notice Retrieves the serialized bytecode of a previously posted Witnet Data Request.
    /// @dev Fails if the `_queryId` is not valid, or if the related script bytecode 
    /// @dev got changed after being posted. Returns empty array once it gets reported, 
    /// @dev or deleted.
    /// @param _queryId The unique query identifier.
    function readRequestBytecode(uint256 _queryId) external view returns (bytes memory);

    /// @notice Retrieves the gas price that any assigned reporter will have to pay when reporting 
    /// result to a previously posted Witnet data request.
    /// @dev Fails if the `_queryId` is not valid or, if it has already been 
    /// @dev reported, or deleted. 
    /// @param _queryId The unique query identifie
    function readRequestGasPrice(uint256 _queryId) external view returns (uint256);

    /// @notice Retrieves the reward currently set for the referred query.
    /// @dev Fails if the `_queryId` is not valid or, if it has already been 
    /// @dev reported, or deleted. 
    /// @param _queryId The unique query identifier.
    function readRequestReward(uint256 _queryId) external view returns (uint256);

    /// @notice Retrieves the whole `Witnet.Response` record referred to a previously posted Witnet Data Request.
    /// @dev Fails if the `_queryId` is not in 'Reported' status.
    /// @param _queryId The unique query identifier.
    function readResponse(uint256 _queryId) external view returns (Witnet.Response memory);

    /// @notice Retrieves error codes of given query.
    /// @dev Fails if the `_queryId` is not in 'Reported' status, or if no actual error.
    /// @param _queryId The unique query identifier.
    function readResponseDrTxHash(uint256 _queryId) external view returns (bytes32);

    /// @notice Retrieves the address that reported the result to a previously-posted request.
    /// @dev Fails if the `_queryId` is not in 'Reported' status.
    /// @param _queryId The unique query identifier.
    function readResponseReporter(uint256 _queryId) external view returns (address);

    /// @notice Retrieves the Witnet-provided CBOR-bytes result of a previously posted request.
    /// @dev Fails if the `_queryId` is not in 'Reported' status.
    /// @param _queryId The unique query identifier.
    function readResponseResult(uint256 _queryId) external view returns (Witnet.Result memory);

    /// @notice Retrieves the timestamp in which the result to the referred query was solved by the Witnet DON.
    /// @dev Fails if the `_queryId` is not in 'Reported' status.
    /// @param _queryId The unique query identifier.
    function readResponseTimestamp(uint256 _queryId) external view returns (uint256);
}

/// @title Witnet Request Board info interface.
/// @author The Witnet Foundation.
interface IWitnetRequestBoardDeprecating {

    /// ===============================================================================================================
    /// --- Deprecating funcionality v0.5 -----------------------------------------------------------------------------
    
    /// Tell if a Witnet.Result is successful.
    /// @param _result An instance of Witnet.Result.
    /// @return `true` if successful, `false` if errored.
    function isOk(Witnet.Result memory _result) external pure returns (bool);

    /// Decode a bytes value from a Witnet.Result as a `bytes32` value.
    /// @param _result An instance of Witnet.Result.
    /// @return The `bytes32` decoded from the Witnet.Result.
    function asBytes32(Witnet.Result memory _result) external pure returns (bytes32);

    /// Generate a suitable error message for a member of `Witnet.ResultErrorCodes` and its corresponding arguments.
    /// @dev WARN: Note that client contracts should wrap this function into a try-catch foreseing potential errors generated in this function
    /// @param _result An instance of `Witnet.Result`.
    /// @return A tuple containing the `CBORValue.Error memory` decoded from the `Witnet.Result`, plus a loggable error message.
    function asErrorMessage(Witnet.Result memory _result) external pure returns (Witnet.ResultErrorCodes, string memory);

    /// Decode a natural numeric value from a Witnet.Result as a `uint` value.
    /// @param _result An instance of Witnet.Result.
    /// @return The `uint` decoded from the Witnet.Result.
    function asUint64(Witnet.Result memory _result) external pure returns (uint64);

    /// Decode raw CBOR bytes into a Witnet.Result instance.
    /// @param _cborBytes Raw bytes representing a CBOR-encoded value.
    /// @return A `Witnet.Result` instance.
    function resultFromCborBytes(bytes memory _cborBytes) external pure returns (Witnet.Result memory);

}

/// @title Witnet Request Board functionality base contract.
/// @author The Witnet Foundation.
abstract contract WitnetRequestBoard is
    IWitnetRequestBoardDeprecating,
    IWitnetRequestBoardEvents,
    IWitnetRequestBoardReporter,
    IWitnetRequestBoardRequestor,
    IWitnetRequestBoardView
{
    WitnetRequestFactory immutable public factory;
    WitnetBytecodes immutable public registry;
    constructor (WitnetRequestFactory _factory) {
        require(
            _factory.class() == type(WitnetRequestFactory).interfaceId,
            "WitnetRequestBoard: uncompliant factory"
        );
        factory = _factory;
        registry = _factory.registry();
    }
}

interface IWitnetFeeds {
    function dataType() external view returns (WitnetV2.RadonDataTypes);
    function prefix() external view returns (string memory);
    function registry() external view returns (WitnetBytecodes);
    function witnet() external view returns (WitnetRequestBoard);
    
    function defaultRadonSLA() external view returns (WitnetV2.RadonSLA memory);
    
    function estimateUpdateBaseFee(bytes4 feedId, uint256 evmGasPrice, uint256 witEvmPrice) external view returns (uint);
    function estimateUpdateBaseFee(bytes4 feedId, uint256 evmGasPrice, uint256 witEvmPrice, bytes32 slaHash) external view returns (uint);

    function latestResponse(bytes4 feedId) external view returns (Witnet.Response memory);
    function latestResult(bytes4 feedId) external view returns (Witnet.Result memory);

    function latestUpdateQueryId(bytes4 feedId) external view returns (uint256);
    function latestUpdateRequest(bytes4 feedId) external view returns (Witnet.Request memory);
    function latestUpdateResponse(bytes4 feedId) external view returns (Witnet.Response memory);
    function latestUpdateResultError(bytes4 feedId) external view returns (Witnet.ResultError memory);
    function latestUpdateResultStatus(bytes4 feedId) external view returns (Witnet.ResultStatus);

    function lookupBytecode(bytes4 feedId) external view returns (bytes memory);
    function lookupRadHash(bytes4 feedId) external view returns (bytes32);
    function lookupRetrievals(bytes4 feedId) external view returns (WitnetV2.RadonRetrieval[] memory);

    function requestUpdate(bytes4 feedId) external payable returns (uint256 usedFunds);
    function requestUpdate(bytes4 feedId, bytes32 slaHash) external payable returns (uint256 usedFunds);
}

abstract contract WitnetRequestTemplate
{
    event WitnetRequestBuilt(address indexed request, bytes32 indexed radHash, string[][] args);

    function class() virtual external view returns (bytes4);
    function factory() virtual external view returns (WitnetRequestFactory);
    function registry() virtual external view returns (WitnetBytecodes);
    function version() virtual external view returns (string memory);

    function aggregator() virtual external view returns (bytes32);
    function parameterized() virtual external view returns (bool);
    function resultDataMaxSize() virtual external view returns (uint16);
    function resultDataType() virtual external view returns (WitnetV2.RadonDataTypes);
    function retrievals() virtual external view returns (bytes32[] memory);
    function tally() virtual external view returns (bytes32);
    
    function getRadonAggregator() virtual external view returns (WitnetV2.RadonReducer memory);
    function getRadonRetrievalByIndex(uint256) virtual external view returns (WitnetV2.RadonRetrieval memory);
    function getRadonRetrievalsCount() virtual external view returns (uint256);
    function getRadonTally() virtual external view returns (WitnetV2.RadonReducer memory);
    
    function buildRequest(string[][] calldata args) virtual external returns (address);
    function verifyRadonRequest(string[][] calldata args) virtual external returns (bytes32);
}

abstract contract WitnetRequest
    is
        WitnetRequestTemplate
{
    /// introspection methods
    function template() virtual external view returns (WitnetRequestTemplate);

    /// request-exclusive fields
    function args() virtual external view returns (string[][] memory);
    function bytecode() virtual external view returns (bytes memory);
    function radHash() virtual external view returns (bytes32);
}

interface IWitnetFeedsAdmin {
    function deleteFeed(string calldata caption) external;
    function settleDefaultRadonSLA(WitnetV2.RadonSLA calldata) external;
    function settleFeedRequest(string calldata caption, bytes32 radHash) external;
    function settleFeedRequest(string calldata caption, WitnetRequest request) external;
    function settleFeedRequest(string calldata caption, WitnetRequestTemplate template, string[][] calldata) external;
    function settleFeedSolver(string calldata caption, address solver, string[] calldata deps) external;
}

interface IWitnetFeedsEvents {
    event DeletedFeed(address indexed from, bytes4 indexed feedId, string caption);
    event SettledFeed(address indexed from, bytes4 indexed feedId, string caption, bytes32 radHash);
    event SettledFeedSolver(address indexed from, bytes4 indexed feedId, string caption, address solver);
    event SettledRadonSLA(address indexed from, bytes32 slaHash);
    event UpdatingFeed(address indexed from, bytes4 indexed feedId, bytes32 slaHash, uint256 value);
    event UpdatingFeedReward(address indexed from, bytes4 indexed feedId, uint256 value);
}

abstract contract WitnetFeeds
    is 
        IFeeds,
        IWitnetFeeds,
        IWitnetFeedsAdmin,
        IWitnetFeedsEvents
{
    WitnetV2.RadonDataTypes immutable public override dataType;
    WitnetBytecodes immutable public override registry;
    WitnetRequestBoard immutable public override witnet;

    bytes32 immutable internal __prefix;

    constructor(
            WitnetRequestBoard _wrb,
            WitnetV2.RadonDataTypes _dataType,
            string memory _prefix
        )
    {
        witnet = _wrb;
        registry = witnet.registry();
        dataType = _dataType;
        __prefix = Witnet.toBytes32(bytes(_prefix));
    }

    function prefix() override public view returns (string memory) {
        return Witnet.toString(__prefix);
    }
}

abstract contract WitnetPriceFeeds
    is
        IERC2362,
        IWitnetPriceFeeds,
        IWitnetPriceSolverDeployer,
        WitnetFeeds
{   
    constructor(WitnetRequestBoard _wrb)
        WitnetFeeds(
            _wrb,
            WitnetV2.RadonDataTypes.Integer,
            "Price-"
        )
    {}
}

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

/// @title The Witnet Price Feed basic interface.
/// @dev Guides implementation of active price feed polling contracts.
/// @author The Witnet Foundation.

interface IWitnetPriceFeed {

    /// Signals that a new price update request is being posted to the Witnet Request Board
    event PriceFeeding(address indexed from, uint256 queryId, uint256 extraFee);

    /// @notice Estimates minimum fee amount in native currency to be paid when 
    /// @notice requesting a new price update.
    /// @dev Actual fee depends on the gas price of the `requestUpdate()` transaction.
    /// @param _gasPrice Gas price expected to be paid when calling `requestUpdate()`
    function estimateUpdateFee(uint256 _gasPrice) external view returns (uint256);

    /// @notice Returns result of the last valid price update request successfully solved by the Witnet oracle.
    function lastPrice() external view returns (int256);

    /// @notice Returns the EVM-timestamp when last valid price was reported back from the Witnet oracle.
    function lastTimestamp() external view returns (uint256);    

    /// @notice Returns tuple containing last valid price and timestamp, as well as status code of latest update
    /// @notice request that got posted to the Witnet Request Board.
    /// @return _lastPrice Last valid price reported back from the Witnet oracle.
    /// @return _lastTimestamp EVM-timestamp of the last valid price.
    /// @return _lastDrTxHash Hash of the Witnet Data Request that solved the last valid price.
    /// @return _latestUpdateStatus Status code of the latest update request.
    function lastValue() external view returns (
        int _lastPrice,
        uint _lastTimestamp,
        bytes32 _lastDrTxHash,
        uint _latestUpdateStatus
    );

    /// @notice Returns identifier of the latest update request posted to the Witnet Request Board.
    function latestQueryId() external view returns (uint256);

    /// @notice Returns hash of the Witnet Data Request that solved the latest update request.
    /// @dev Returning 0 while the latest update request remains unsolved.
    function latestUpdateDrTxHash() external view returns (bytes32);

    /// @notice Returns error message of latest update request posted to the Witnet Request Board.
    /// @dev Returning empty string if the latest update request remains unsolved, or
    /// @dev if it was succesfully solved with no errors.
    function latestUpdateErrorMessage() external view returns (string memory);

    /// @notice Returns status code of latest update request posted to the Witnet Request Board:
    /// @dev Status codes:
    /// @dev   - 200: update request was succesfully solved with no errors
    /// @dev   - 400: update request was solved with errors
    /// @dev   - 404: update request was not solved yet 
    function latestUpdateStatus() external view returns (uint256);

    /// @notice Returns `true` if latest update request posted to the Witnet Request Board 
    /// @notice has not been solved yet by the Witnet oracle.
    function pendingUpdate() external view returns (bool);

    /// @notice Posts a new price update request to the Witnet Request Board. Requires payment of a fee
    /// @notice that depends on the value of `tx.gasprice`. See `estimateUpdateFee(uint256)`.
    /// @dev If previous update request was not solved yet, calling this method again allows
    /// @dev upgrading the update fee if called with a higher `tx.gasprice` value.
    function requestUpdate() external payable;

    /// @notice Tells whether this contract implements the interface defined by `interfaceId`. 
    /// @dev See the corresponding https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
    /// @dev to learn more about how these ids are created.
    function supportsInterface(bytes4) external view returns (bool);
}

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     * @custom:oz-retyped-from bool
     */
    uint8 private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint8 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts.
     *
     * Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
     * constructor.
     *
     * Emits an {Initialized} event.
     */
    modifier initializer() {
        bool isTopLevelCall = !_initializing;
        require(
            (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
            "Initializable: contract is already initialized"
        );
        _initialized = 1;
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(1);
        }
    }

    /**
     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
     * used to initialize parent contracts.
     *
     * A reinitializer may be used after the original initialization step. This is essential to configure modules that
     * are added through upgrades and that require initialization.
     *
     * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
     * cannot be nested. If one is invoked in the context of another, execution will revert.
     *
     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
     * a contract, executing them in the right order is up to the developer or operator.
     *
     * WARNING: setting the version to 255 will prevent any future reinitialization.
     *
     * Emits an {Initialized} event.
     */
    modifier reinitializer(uint8 version) {
        require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
        _initialized = version;
        _initializing = true;
        _;
        _initializing = false;
        emit Initialized(version);
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} and {reinitializer} modifiers, directly or indirectly.
     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    /**
     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
     * through proxies.
     *
     * Emits an {Initialized} event the first time it is successfully executed.
     */
    function _disableInitializers() internal virtual {
        require(!_initializing, "Initializable: contract is initializing");
        if (_initialized < type(uint8).max) {
            _initialized = type(uint8).max;
            emit Initialized(type(uint8).max);
        }
    }

    /**
     * @dev Internal function that returns the initialized version. Returns `_initialized`
     */
    function _getInitializedVersion() internal view returns (uint8) {
        return _initialized;
    }

    /**
     * @dev Internal function that returns the initialized version. Returns `_initializing`
     */
    function _isInitializing() internal view returns (bool) {
        return _initializing;
    }
}

abstract contract Clonable
    is
        Initializable
{
    address immutable internal _SELF = address(this);

    event Cloned(address indexed by, address indexed self, address indexed clone);

    modifier onlyDelegateCalls virtual {
        require(address(this) != _SELF, "Clonable: not a delegate call");
        _;
    }

    modifier wasInitialized {
        require(initialized(), "Clonable: not initialized");
        _;
    }

    /// @notice Tells whether this contract is a clone of `self()`
    function cloned()
        public view
        returns (bool)
    {
        return (
            address(this) != self()
        );
    }

    /// @notice Tells whether this instance has been initialized.
    function initialized() virtual public view returns (bool);

    /// @notice Contract address to which clones will be re-directed.
    function self() virtual public view returns (address) {
        return _SELF;
    }

    /// Deploys and returns the address of a minimal proxy clone that replicates contract
    /// behaviour while using its own EVM storage.
    /// @dev This function should always provide a new address, no matter how many times 
    /// @dev is actually called from the same `msg.sender`.
    /// @dev See https://eips.ethereum.org/EIPS/eip-1167.
    /// @dev See https://blog.openzeppelin.com/deep-dive-into-the-minimal-proxy-contract/.
    function _clone()
        internal
        returns (address _instance)
    {
        bytes memory ptr = _cloneBytecodePtr();
        assembly {
            // CREATE new instance:
            _instance := create(0, ptr, 0x37)
        }        
        require(_instance != address(0), "Clonable: CREATE failed");
        emit Cloned(msg.sender, self(), _instance);
    }

    /// @notice Returns minimal proxy's deploy bytecode.
    function _cloneBytecode()
        virtual internal view
        returns (bytes memory)
    {
        return abi.encodePacked(
            hex"3d602d80600a3d3981f3363d3d373d3d3d363d73",
            bytes20(self()),
            hex"5af43d82803e903d91602b57fd5bf3"
        );
    }

    /// @notice Returns mem pointer to minimal proxy's deploy bytecode.
    function _cloneBytecodePtr()
        virtual internal view
        returns (bytes memory ptr)
    {
        address _base = self();
        assembly {
            // ptr to free mem:
            ptr := mload(0x40)
            // begin minimal proxy construction bytecode:
            mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
            // make minimal proxy delegate all calls to `self()`:
            mstore(add(ptr, 0x14), shl(0x60, _base))
            // end minimal proxy construction bytecode:
            mstore(add(ptr, 0x28), 0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000)
        }
    }

    /// Deploys and returns the address of a minimal proxy clone that replicates contract 
    /// behaviour while using its own EVM storage.
    /// @dev This function uses the CREATE2 opcode and a `_salt` to deterministically deploy
    /// @dev the clone. Using the same `_salt` multiple times will revert, since
    /// @dev no contract can be deployed more than once at the same address.
    /// @dev See https://eips.ethereum.org/EIPS/eip-1167.
    /// @dev See https://blog.openzeppelin.com/deep-dive-into-the-minimal-proxy-contract/.
    function _cloneDeterministic(bytes32 _salt)
        virtual internal
        returns (address _instance)
    {
        bytes memory ptr = _cloneBytecodePtr();
        assembly {
            // CREATE2 new instance:
            _instance := create2(0, ptr, 0x37, _salt)
        }
        require(_instance != address(0), "Clonable: CREATE2 failed");
        emit Cloned(msg.sender, self(), _instance);
    }
}

// Your contract needs to inherit from UsingWitnet
contract WitnetPriceFeedBypass
    is
        Clonable,
        IWitnetPriceFeed,
        IWitnetRequest
{
    WitnetPriceFeeds immutable public feeds;
    WitnetRequestBoard immutable public witnet;

    string public caption;
    bytes4 public feedId;

    constructor(WitnetPriceFeeds _feeds) {
        assert(address(_feeds) != address(0));
        feeds = _feeds;
        witnet = feeds.witnet();
    }

    receive() external payable {}

    function cloneAndInitialize(string calldata _caption)
        virtual external
        returns (WitnetPriceFeedBypass)
    {
        return WitnetPriceFeedBypass(payable(_clone())).initializeClone(_caption);
    }


    /// ===============================================================================================================
    /// --- Clonable implementation -----------------------------------------------------------------------------------

    function initializeClone(string calldata _caption)
        virtual external
        initializer
        onlyDelegateCalls
        returns (WitnetPriceFeedBypass)
    {
        require(
            feeds.supportsCaption(_caption), 
            string(abi.encodePacked(
                "WitnetPriceFeedBypass: unsupported '",
                _caption,
                "'"
            ))
        );
        caption = _caption;
        feedId = bytes4(keccak256(bytes(_caption)));
        return WitnetPriceFeedBypass(payable(address(this)));
    }

    function initialized() virtual override public view returns (bool) {
        return feedId != 0;
    }

    
    /// ===============================================================================================================
    /// --- IWitnetRequest implementation -----------------------------------------------------------------------------

    function bytecode() override external view returns (bytes memory) {
        return feeds.lookupBytecode(feedId);
    }

    function hash() override external view returns (bytes32) {
        return feeds.lookupRadHash(feedId);
    }


    /// ===============================================================================================================
    /// --- IWitnetPriceFeed implementation ---------------------------------------------------------------------------

    /// @notice Estimates minimum fee amount in native currency to be paid when 
    /// @notice requesting a new price update.
    /// @dev Actual fee depends on the gas price of the `requestUpdate()` transaction.
    /// @param _gasPrice Gas price expected to be paid when calling `requestUpdate()`
    function estimateUpdateFee(uint256 _gasPrice)
        override
        external view
        returns (uint256)
    {
        return feeds.estimateUpdateBaseFee(feedId, _gasPrice, 0);
    }

    /// @notice Returns result of the last valid price update request successfully solved by the Witnet oracle.
    function lastPrice()
        override
        external view
        returns (int256)
    {
        IWitnetPriceSolver.Price memory _price = feeds.latestPrice(feedId);
        return int(_price.value);
    }

    /// @notice Returns the EVM-timestamp when last valid price was reported back from the Witnet oracle.
    function lastTimestamp()
        override 
        external view
        returns (uint256)
    {
        IWitnetPriceSolver.Price memory _price = feeds.latestPrice(feedId);
        return _price.timestamp;
    }

    /// @notice Returns tuple containing last valid price and timestamp, as well as status code of latest update
    /// @notice request that got posted to the Witnet Request Board.
    /// @return _lastPrice Last valid price reported back from the Witnet oracle.
    /// @return _lastTimestamp EVM-timestamp of the last valid price.
    /// @return _lastDrTxHash Hash of the Witnet Data Request that solved the last valid price.
    /// @return _latestUpdateStatus Status code of the latest update request.
    function lastValue()
        override
        external view
        returns (
            int _lastPrice,
            uint _lastTimestamp,
            bytes32 _lastDrTxHash,
            uint _latestUpdateStatus
        )
    {
        IWitnetPriceSolver.Price memory _price = feeds.latestPrice(feedId);
        _lastPrice = int(_price.value);
        _lastTimestamp = _price.timestamp;
        _lastDrTxHash = _price.drTxHash;
        if (_price.status == Witnet.ResultStatus.Ready) {
            _latestUpdateStatus = 200;
        } else if (_price.status == Witnet.ResultStatus.Awaiting) {
            _latestUpdateStatus = 404;
        } else {
            _latestUpdateStatus = 400;
        }
    }

    /// @notice Returns identifier of the latest update request posted to the Witnet Request Board.
    function latestQueryId()
        override
        external view
        returns (uint256)
    {
        return feeds.latestUpdateQueryId(feedId);
    }

    /// @notice Returns hash of the Witnet Data Request that solved the latest update request.
    /// @dev Returning 0 while the latest update request remains unsolved.
    function latestUpdateDrTxHash()
        override
        external view
        returns (bytes32)
    {
        IWitnetPriceSolver.Price memory _price = feeds.latestPrice(feedId);
        return _price.drTxHash;
    }

    /// @notice Returns error message of latest update request posted to the Witnet Request Board.
    /// @dev Returning empty string if the latest update request remains unsolved, or
    /// @dev if it was succesfully solved with no errors.
    function latestUpdateErrorMessage()
        override
        external view
        returns (string memory)
    {
        Witnet.ResultError memory _error = feeds.latestUpdateResultError(feedId);
        return _error.reason;
    }

    /// @notice Returns status code of latest update request posted to the Witnet Request Board:
    /// @dev Status codes:
    /// @dev   - 200: update request was succesfully solved with no errors
    /// @dev   - 400: update request was solved with errors
    /// @dev   - 404: update request was not solved yet 
    function latestUpdateStatus()
        override
        external view
        returns (uint256)
    {
        Witnet.ResultStatus _status = feeds.latestUpdateResultStatus(feedId);
        if (_status == Witnet.ResultStatus.Ready) {
            return 200;
        } else if (_status == Witnet.ResultStatus.Awaiting) {
            return 404;
        } else {
            return 400;
        }
    }

    /// @notice Returns `true` if latest update request posted to the Witnet Request Board 
    /// @notice has not been solved yet by the Witnet oracle.
    function pendingUpdate()
        override
        external view
        returns (bool)
    {
        return feeds.latestUpdateResultStatus(feedId) == Witnet.ResultStatus.Awaiting;
    }

    /// @notice Posts a new price update request to the Witnet Request Board. Requires payment of a fee
    /// @notice that depends on the value of `tx.gasprice`. See `estimateUpdateFee(uint256)`.
    /// @dev If previous update request was not solved yet, calling this method again allows
    /// @dev upgrading the update fee if called with a higher `tx.gasprice` value.
    function requestUpdate()
        override
        external payable
    {
        uint _usedFunds = feeds.requestUpdate{value: msg.value}(feedId);
        if (_usedFunds < msg.value) {
            payable(msg.sender).transfer(msg.value - _usedFunds);
        }
        emit PriceFeeding(
            msg.sender,
            feeds.latestUpdateQueryId(feedId),
            _usedFunds
        );
    }

    /// @notice Tells whether this contract implements the interface defined by `interfaceId`. 
    /// @dev See the corresponding https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
    /// @dev to learn more about how these ids are created.
    function supportsInterface(bytes4 _id)
        override
        external pure
        returns (bool)
    {
        return (
            _id == type(IWitnetPriceFeed).interfaceId
                || _id == type(IERC165).interfaceId
        );
    }
}