// "SPDX-License-Identifier: UNLICENSED"
pragma solidity 0.6.12;

import {
    GelatoConditionsStandard
} from "@gelatonetwork/core/contracts/conditions/GelatoConditionsStandard.sol";
import {SafeMath} from "@gelatonetwork/core/contracts/external/SafeMath.sol";
import {IERC20} from "@gelatonetwork/core/contracts/external/IERC20.sol";
import {
    IGelatoCore
} from "@gelatonetwork/core/contracts/gelato_core/interfaces/IGelatoCore.sol";
import {GelatoBytes} from "./GelatoBytes.sol";

/// @notice A general contract for retrieving and comparing 2 uints from 2 contracts.
/// @dev This contract only works if the refContracts fns returndata has a uint in
/// the first 32-byte position.
contract ConditionCompareUintsFromTwoSources is GelatoConditionsStandard {
    using GelatoBytes for bytes;
    using SafeMath for uint256;

    /// @notice Helper to encode the Condition data field off-chain
    function getConditionData(
        address _sourceA,
        address _sourceB,
        bytes calldata  _sourceAData,
        bytes calldata _sourceBData,
        uint256 _minSpread
    )
        public
        pure
        virtual
        returns (bytes memory)
    {
        return abi.encode(_sourceA, _sourceB, _sourceAData, _sourceBData, _minSpread);
    }

    /// @notice Gelato Standard Condition function.
    /// @dev Every Gelato Condition must have this function selector as entry point.
    /// @param _conditionData The encoded data from getConditionData()
     function ok(uint256, bytes calldata _conditionData, uint256)
        public
        view
        virtual
        override
        returns (string memory)
    {
        (address _sourceA,
         address _sourceB,
         bytes memory _sourceAData,
         bytes memory _sourceBData,
         uint256 _minSpread) = abi.decode(
            _conditionData,
            (address,address,bytes,bytes,uint256)
        );
        return compare(_sourceA, _sourceB, _sourceAData, _sourceBData, _minSpread);
    }

    /// @notice Compares 2 values from sourceA and sourceB to check if minSpread is there.
    /// @dev If you want to trigger when ContractA uint is greater than or equal
    /// to ContractB by _minSpread: (ContractA=_sourceA, ContractB=_sourceB)
    /// For the reverse (lower than/equal to): (ContractA=_sourceB, ContractB=_sourceA)
    /// @param _sourceA The first contract that returns a uint for comparison.
    /// @param _sourceB The second contract that returns a uint256 for comparison.
    /// @param _sourceAData Payload for retrieving the uint from _sourceA.
    /// @param _sourceBData Payload for retrieving the uint from _sourceB.
    /// @param _minSpread The minimum diff between sourceA and sourceB
    ///  for the Condition to be relevant.
    /// @return OK if the Condition is fulfilled.
    function compare(
        address _sourceA,
        address _sourceB,
        bytes memory  _sourceAData,
        bytes memory _sourceBData,
        uint256 _minSpread
    )
        public
        view
        virtual
        returns (string memory)
    {
        // Retrieve uint256 from sourceA
        (bool success, bytes memory returndata) = _sourceA.staticcall(_sourceAData);
        if (!success) {
            return returndata.generateErrorString(
                "ConditionCompareTwoUints.compare._sourceA:"
            );
        }
        uint256 a = abi.decode(returndata, (uint256));

        // Retrieve uint256 from sourceB
        (success, returndata) = _sourceB.staticcall(_sourceBData);
        if (!success) {
            return returndata.generateErrorString(
                "ConditionCompareTwoUints.compare._sourceB:"
            );
        }
        uint256 b = abi.decode(returndata, (uint256));

        if (a >= b.add(_minSpread)) return OK;
        return "ANotGreaterOrEqualToBbyMinspread";
    }
}