// SPDX-License-Identifier: MIT
// An example of a consumer contract that relies on a subscription for funding.
pragma solidity 0.8.6;

import "../../shared/access/ConfirmedOwner.sol";
import "../VRFConsumerBaseV2.sol";
import "../interfaces/VRFCoordinatorV2Interface.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT THAT USES HARDCODED VALUES FOR CLARITY.
 * THIS IS AN EXAMPLE CONTRACT THAT USES UN-AUDITED CODE.
 * DO NOT USE THIS CODE IN PRODUCTION.
 */
contract VRFv2Consumer is VRFConsumerBaseV2, ConfirmedOwner {
  event RequestSent(uint256 requestId, uint32 numWords);
  event RequestFulfilled(uint256 requestId, uint256[] randomWords);

  struct RequestStatus {
    bool fulfilled; // whether the request has been successfully fulfilled
    bool exists; // whether a requestId exists
    uint256[] randomWords;
  }

  mapping(uint256 => RequestStatus) public s_requests; /* requestId --> requestStatus */
  VRFCoordinatorV2Interface COORDINATOR;

  // past requests Id.
  uint256[] public requestIds;
  uint256 public lastRequestId;

  constructor(
    address vrfCoordinator
  ) VRFConsumerBaseV2(vrfCoordinator) ConfirmedOwner(msg.sender) {
    COORDINATOR = VRFCoordinatorV2Interface(vrfCoordinator);
  }

  // Assumes the subscription is funded sufficiently.
  function requestRandomWords(
    uint64 subId,
    uint32 callbackGasLimit,
    uint16 requestConfirmations,
    uint32 numWords,
    bytes32 keyHash
  ) external onlyOwner returns (uint256 requestId) {
    // Will revert if subscription is not set and funded.
    requestId = COORDINATOR.requestRandomWords(keyHash, subId, requestConfirmations, callbackGasLimit, numWords);
    s_requests[requestId] = RequestStatus({randomWords: new uint256[](0), exists: true, fulfilled: false});
    requestIds.push(requestId);
    lastRequestId = requestId;
    emit RequestSent(requestId, numWords);
    return requestId;
  }

  function fulfillRandomWords(uint256 _requestId, uint256[] memory _randomWords) internal override {
    require(s_requests[_requestId].exists, "request not found");
    s_requests[_requestId].fulfilled = true;
    s_requests[_requestId].randomWords = _randomWords;
    emit RequestFulfilled(_requestId, _randomWords);
  }

  function getRequestStatus(
    uint256 _requestId
  ) external view returns (bool fulfilled, uint256[] memory randomWords) {
    require(s_requests[_requestId].exists, "request not found");
    RequestStatus memory request = s_requests[_requestId];
    return (request.fulfilled, request.randomWords);
  }
}