// SPDX-License-Identifier: MIT
pragma solidity 0.8.6;

import "./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 {
  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[] memory proofs, VRFTypes.RequestCommitment[] memory rcs) external {
    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)));
  }
}

interface VRFCoordinatorV2 {
  function fulfillRandomWords(VRFTypes.Proof memory proof, VRFTypes.RequestCommitment memory rc)
    external
    returns (uint96);
}