// SPDX-License-Identifier: MIT
// solhint-disable-next-line one-contract-per-file
pragma solidity 0.8.6;

import {VRFTypes} from "./VRFTypes.sol";

/**
 * @title BatchVRFCoordinatorV2
 * @notice The BatchVRFCoordinatorV2 contract acts as a proxy to write many random responses to the
 *   provided VRFCoordinatorV2 contract efficiently in a single transaction.
 */
contract BatchVRFCoordinatorV2 {
  // solhint-disable-next-line chainlink-solidity/prefix-immutable-variables-with-i
  VRFCoordinatorV2 public immutable COORDINATOR;

  event ErrorReturned(uint256 indexed requestId, string reason);
  event RawErrorReturned(uint256 indexed requestId, bytes lowLevelData);

  constructor(
    address coordinatorAddr
  ) {
    COORDINATOR = VRFCoordinatorV2(coordinatorAddr);
  }

  /**
   * @notice fulfills multiple randomness requests with the provided proofs and commitments.
   * @param proofs the randomness proofs generated by the VRF provider.
   * @param rcs the request commitments corresponding to the randomness proofs.
   */
  function fulfillRandomWords(VRFTypes.Proof[] calldata proofs, VRFTypes.RequestCommitment[] memory rcs) external {
    // solhint-disable-next-line gas-custom-errors
    require(proofs.length == rcs.length, "input array arg lengths mismatch");
    for (uint256 i = 0; i < proofs.length; i++) {
      try COORDINATOR.fulfillRandomWords(proofs[i], rcs[i]) returns (uint96 /* payment */ ) {
        continue;
      } catch Error(string memory reason) {
        uint256 requestId = _getRequestIdFromProof(proofs[i]);
        emit ErrorReturned(requestId, reason);
      } catch (bytes memory lowLevelData) {
        uint256 requestId = _getRequestIdFromProof(proofs[i]);
        emit RawErrorReturned(requestId, lowLevelData);
      }
    }
  }

  /**
   * @notice Returns the proving key hash associated with this public key.
   * @param publicKey the key to return the hash of.
   */
  function _hashOfKey(
    uint256[2] memory publicKey
  ) internal pure returns (bytes32) {
    return keccak256(abi.encode(publicKey));
  }

  /**
   * @notice Returns the request ID of the request associated with the given proof.
   * @param proof the VRF proof provided by the VRF oracle.
   */
  function _getRequestIdFromProof(
    VRFTypes.Proof memory proof
  ) internal pure returns (uint256) {
    bytes32 keyHash = _hashOfKey(proof.pk);
    return uint256(keccak256(abi.encode(keyHash, proof.seed)));
  }
}

// solhint-disable-next-line interface-starts-with-i
interface VRFCoordinatorV2 {
  function fulfillRandomWords(
    VRFTypes.Proof calldata proof,
    VRFTypes.RequestCommitment memory rc
  ) external returns (uint96);
}