// SPDX-License-Identifier: MIT
pragma solidity ^0.8.7;

import "@chainlink/contracts/src/v0.8/ChainlinkClient.sol";

/**
 * @title The APIConsumer contract
 * @notice An API Consumer contract that makes GET requests to obtain 24h trading volume of ETH in USD
 */
contract APIConsumer is ChainlinkClient {
    using Chainlink for Chainlink.Request;

    uint256 public volume;
    address private immutable oracle;
    bytes32 private immutable jobId;
    uint256 private immutable fee;

    event DataFullfilled(uint256 volume);

    /**
     * @notice Executes once when a contract is created to initialize state variables
     *
     * @param _oracle - address of the specific Chainlink node that a contract makes an API call from
     * @param _jobId - specific job for :_oracle: to run; each job is unique and returns different types of data
     * @param _fee - node operator price per API call / data request
     * @param _link - LINK token address on the corresponding network
     *
     * Network: Baobab
     * Oracle: 0xfC3BdAbD8a6A73B40010350E2a61716a21c87610
     * Job ID: ca98366cc7314957b8c012c72f05aeeb
     * Fee: 0.1 LINK
     * Link: 0x04c5046A1f4E3fFf094c26dFCAA75eF293932f18
     */
    constructor(
        address _oracle,
        bytes32 _jobId,
        uint256 _fee,
        address _link
    ) {
        if (_link == address(0)) {
            setPublicChainlinkToken();
        } else {
            setChainlinkToken(_link);
        }
        oracle = _oracle;
        jobId = _jobId;
        fee = _fee;
    }

    /**
     * @notice Creates a Chainlink request to retrieve API response, find the target
     * data, then multiply by 10*_coinDecimals (to remove decimal places from data).
     *
     * @return requestId - id of the request
     */
    function requestVolumeData(string memory _coinSymbol, uint8 _coinDecimals) public returns (bytes32 requestId) {
        Chainlink.Request memory request = buildChainlinkRequest(
            jobId,
            address(this),
            this.fulfill.selector
        );

        // Set the URL to perform the GET request on
        request.add(
            "get",
            string(abi.encodePacked("https://min-api.cryptocompare.com/data/pricemultifull?fsyms=", _coinSymbol, "&tsyms=USD"))
        );

        // Set the path to find the desired data in the API response, where the response format is:
        // {"RAW":
        //   {"KLAY":
        //    {"USD":
        //     {
        //      "VOLUME24HOUR": xxx.xxx,
        //     }
        //    }
        //   }
        //  }
        // request.add("path", "RAW.KLAY.USD.VOLUME24HOUR"); // Chainlink nodes prior to 1.0.0 support this format
        request.add("path", "RAW,KLAY,USD,VOLUME24HOUR"); // Chainlink nodes 1.0.0 and later support this format

        // Multiply the result by 10**_coinDecimals to remove decimals
        int256 timesAmount = int256(10**_coinDecimals);
        request.addInt("times", timesAmount);

        // Sends the request
        return sendChainlinkRequestTo(oracle, request, fee);
    }

    /**
     * @notice Receives the response in the form of uint256
     *
     * @param _requestId - id of the request
     * @param _volume - response; requested 24h trading volume of ETH in USD
     */
    function fulfill(bytes32 _requestId, uint256 _volume)
        public
        recordChainlinkFulfillment(_requestId)
    {
        volume = _volume;
        emit DataFullfilled(volume);
    }

    /**
     * @notice Witdraws LINK from the contract
     * @dev Implement a withdraw function to avoid locking your LINK in the contract
     */
    function withdrawLink() external {}
}