// File: @chainlink/contracts/src/v0.8/interfaces/VRFCoordinatorV2Interface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface VRFCoordinatorV2Interface {
  /**
   * @notice Get configuration relevant for making requests
   * @return minimumRequestConfirmations global min for request confirmations
   * @return maxGasLimit global max for request gas limit
   * @return s_provingKeyHashes list of registered key hashes
   */
  function getRequestConfig()
    external
    view
    returns (
      uint16,
      uint32,
      bytes32[] memory
    );

  /**
   * @notice Request a set of random words.
   * @param keyHash - Corresponds to a particular oracle job which uses
   * that key for generating the VRF proof. Different keyHash's have different gas price
   * ceilings, so you can select a specific one to bound your maximum per request cost.
   * @param subId  - The ID of the VRF subscription. Must be funded
   * with the minimum subscription balance required for the selected keyHash.
   * @param minimumRequestConfirmations - How many blocks you'd like the
   * oracle to wait before responding to the request. See SECURITY CONSIDERATIONS
   * for why you may want to request more. The acceptable range is
   * [minimumRequestBlockConfirmations, 200].
   * @param callbackGasLimit - How much gas you'd like to receive in your
   * fulfillRandomWords callback. Note that gasleft() inside fulfillRandomWords
   * may be slightly less than this amount because of gas used calling the function
   * (argument decoding etc.), so you may need to request slightly more than you expect
   * to have inside fulfillRandomWords. The acceptable range is
   * [0, maxGasLimit]
   * @param numWords - The number of uint256 random values you'd like to receive
   * in your fulfillRandomWords callback. Note these numbers are expanded in a
   * secure way by the VRFCoordinator from a single random value supplied by the oracle.
   * @return requestId - A unique identifier of the request. Can be used to match
   * a request to a response in fulfillRandomWords.
   */
  function requestRandomWords(
    bytes32 keyHash,
    uint64 subId,
    uint16 minimumRequestConfirmations,
    uint32 callbackGasLimit,
    uint32 numWords
  ) external returns (uint256 requestId);

  /**
   * @notice Create a VRF subscription.
   * @return subId - A unique subscription id.
   * @dev You can manage the consumer set dynamically with addConsumer/removeConsumer.
   * @dev Note to fund the subscription, use transferAndCall. For example
   * @dev  LINKTOKEN.transferAndCall(
   * @dev    address(COORDINATOR),
   * @dev    amount,
   * @dev    abi.encode(subId));
   */
  function createSubscription() external returns (uint64 subId);

  /**
   * @notice Get a VRF subscription.
   * @param subId - ID of the subscription
   * @return balance - LINK balance of the subscription in juels.
   * @return reqCount - number of requests for this subscription, determines fee tier.
   * @return owner - owner of the subscription.
   * @return consumers - list of consumer address which are able to use this subscription.
   */
  function getSubscription(uint64 subId)
    external
    view
    returns (
      uint96 balance,
      uint64 reqCount,
      address owner,
      address[] memory consumers
    );

  /**
   * @notice Request subscription owner transfer.
   * @param subId - ID of the subscription
   * @param newOwner - proposed new owner of the subscription
   */
  function requestSubscriptionOwnerTransfer(uint64 subId, address newOwner) external;

  /**
   * @notice Request subscription owner transfer.
   * @param subId - ID of the subscription
   * @dev will revert if original owner of subId has
   * not requested that msg.sender become the new owner.
   */
  function acceptSubscriptionOwnerTransfer(uint64 subId) external;

  /**
   * @notice Add a consumer to a VRF subscription.
   * @param subId - ID of the subscription
   * @param consumer - New consumer which can use the subscription
   */
  function addConsumer(uint64 subId, address consumer) external;

  /**
   * @notice Remove a consumer from a VRF subscription.
   * @param subId - ID of the subscription
   * @param consumer - Consumer to remove from the subscription
   */
  function removeConsumer(uint64 subId, address consumer) external;

  /**
   * @notice Cancel a subscription
   * @param subId - ID of the subscription
   * @param to - Where to send the remaining LINK to
   */
  function cancelSubscription(uint64 subId, address to) external;

  /*
   * @notice Check to see if there exists a request commitment consumers
   * for all consumers and keyhashes for a given sub.
   * @param subId - ID of the subscription
   * @return true if there exists at least one unfulfilled request for the subscription, false
   * otherwise.
   */
  function pendingRequestExists(uint64 subId) external view returns (bool);
}

// File: @chainlink/contracts/src/v0.8/VRFConsumerBaseV2.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/** ****************************************************************************
 * @notice Interface for contracts using VRF randomness
 * *****************************************************************************
 * @dev PURPOSE
 *
 * @dev Reggie the Random Oracle (not his real job) wants to provide randomness
 * @dev to Vera the verifier in such a way that Vera can be sure he's not
 * @dev making his output up to suit himself. Reggie provides Vera a public key
 * @dev to which he knows the secret key. Each time Vera provides a seed to
 * @dev Reggie, he gives back a value which is computed completely
 * @dev deterministically from the seed and the secret key.
 *
 * @dev Reggie provides a proof by which Vera can verify that the output was
 * @dev correctly computed once Reggie tells it to her, but without that proof,
 * @dev the output is indistinguishable to her from a uniform random sample
 * @dev from the output space.
 *
 * @dev The purpose of this contract is to make it easy for unrelated contracts
 * @dev to talk to Vera the verifier about the work Reggie is doing, to provide
 * @dev simple access to a verifiable source of randomness. It ensures 2 things:
 * @dev 1. The fulfillment came from the VRFCoordinator
 * @dev 2. The consumer contract implements fulfillRandomWords.
 * *****************************************************************************
 * @dev USAGE
 *
 * @dev Calling contracts must inherit from VRFConsumerBase, and can
 * @dev initialize VRFConsumerBase's attributes in their constructor as
 * @dev shown:
 *
 * @dev   contract VRFConsumer {
 * @dev     constructor(<other arguments>, address _vrfCoordinator, address _link)
 * @dev       VRFConsumerBase(_vrfCoordinator) public {
 * @dev         <initialization with other arguments goes here>
 * @dev       }
 * @dev   }
 *
 * @dev The oracle will have given you an ID for the VRF keypair they have
 * @dev committed to (let's call it keyHash). Create subscription, fund it
 * @dev and your consumer contract as a consumer of it (see VRFCoordinatorInterface
 * @dev subscription management functions).
 * @dev Call requestRandomWords(keyHash, subId, minimumRequestConfirmations,
 * @dev callbackGasLimit, numWords),
 * @dev see (VRFCoordinatorInterface for a description of the arguments).
 *
 * @dev Once the VRFCoordinator has received and validated the oracle's response
 * @dev to your request, it will call your contract's fulfillRandomWords method.
 *
 * @dev The randomness argument to fulfillRandomWords is a set of random words
 * @dev generated from your requestId and the blockHash of the request.
 *
 * @dev If your contract could have concurrent requests open, you can use the
 * @dev requestId returned from requestRandomWords to track which response is associated
 * @dev with which randomness request.
 * @dev See "SECURITY CONSIDERATIONS" for principles to keep in mind,
 * @dev if your contract could have multiple requests in flight simultaneously.
 *
 * @dev Colliding `requestId`s are cryptographically impossible as long as seeds
 * @dev differ.
 *
 * *****************************************************************************
 * @dev SECURITY CONSIDERATIONS
 *
 * @dev A method with the ability to call your fulfillRandomness method directly
 * @dev could spoof a VRF response with any random value, so it's critical that
 * @dev it cannot be directly called by anything other than this base contract
 * @dev (specifically, by the VRFConsumerBase.rawFulfillRandomness method).
 *
 * @dev For your users to trust that your contract's random behavior is free
 * @dev from malicious interference, it's best if you can write it so that all
 * @dev behaviors implied by a VRF response are executed *during* your
 * @dev fulfillRandomness method. If your contract must store the response (or
 * @dev anything derived from it) and use it later, you must ensure that any
 * @dev user-significant behavior which depends on that stored value cannot be
 * @dev manipulated by a subsequent VRF request.
 *
 * @dev Similarly, both miners and the VRF oracle itself have some influence
 * @dev over the order in which VRF responses appear on the blockchain, so if
 * @dev your contract could have multiple VRF requests in flight simultaneously,
 * @dev you must ensure that the order in which the VRF responses arrive cannot
 * @dev be used to manipulate your contract's user-significant behavior.
 *
 * @dev Since the block hash of the block which contains the requestRandomness
 * @dev call is mixed into the input to the VRF *last*, a sufficiently powerful
 * @dev miner could, in principle, fork the blockchain to evict the block
 * @dev containing the request, forcing the request to be included in a
 * @dev different block with a different hash, and therefore a different input
 * @dev to the VRF. However, such an attack would incur a substantial economic
 * @dev cost. This cost scales with the number of blocks the VRF oracle waits
 * @dev until it calls responds to a request. It is for this reason that
 * @dev that you can signal to an oracle you'd like them to wait longer before
 * @dev responding to the request (however this is not enforced in the contract
 * @dev and so remains effective only in the case of unmodified oracle software).
 */
abstract contract VRFConsumerBaseV2 {
  error OnlyCoordinatorCanFulfill(address have, address want);
  address private immutable vrfCoordinator;

  /**
   * @param _vrfCoordinator address of VRFCoordinator contract
   */
  constructor(address _vrfCoordinator) {
    vrfCoordinator = _vrfCoordinator;
  }

  /**
   * @notice fulfillRandomness handles the VRF response. Your contract must
   * @notice implement it. See "SECURITY CONSIDERATIONS" above for important
   * @notice principles to keep in mind when implementing your fulfillRandomness
   * @notice method.
   *
   * @dev VRFConsumerBaseV2 expects its subcontracts to have a method with this
   * @dev signature, and will call it once it has verified the proof
   * @dev associated with the randomness. (It is triggered via a call to
   * @dev rawFulfillRandomness, below.)
   *
   * @param requestId The Id initially returned by requestRandomness
   * @param randomWords the VRF output expanded to the requested number of words
   */
  function fulfillRandomWords(uint256 requestId, uint256[] memory randomWords) internal virtual;

  // rawFulfillRandomness is called by VRFCoordinator when it receives a valid VRF
  // proof. rawFulfillRandomness then calls fulfillRandomness, after validating
  // the origin of the call
  function rawFulfillRandomWords(uint256 requestId, uint256[] memory randomWords) external {
    if (msg.sender != vrfCoordinator) {
      revert OnlyCoordinatorCanFulfill(msg.sender, vrfCoordinator);
    }
    fulfillRandomWords(requestId, randomWords);
  }
}

// File: contracts/vrf/RandomNumberGenerator.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.9;

import "@chainlink/contracts/src/v0.8/interfaces/VRFCoordinatorV2Interface.sol";
import "@chainlink/contracts/src/v0.8/VRFConsumerBaseV2.sol";

/**
 * @title The RandomNumberGenerator contract
 * @notice A contract that gets random values from Chainlink VRF V2
 */
contract RandomNumberGenerator is VRFConsumerBaseV2 {
    /// @notice Params for the request that will be written to the logs
    struct Params {
        address partnerContract;
        uint32 totalEntries;
        uint32 totalSelections;
        string title;
    }

    VRFCoordinatorV2Interface immutable COORDINATOR;

    /// @notice Your subscription ID.
    uint64 private immutable _subscriptionId;

    // The gas lane to use, which specifies the maximum gas price to bump to.
    // For a list of available gas lanes on each network,
    // see https://docs.chain.link/docs/vrf-contracts/#configurations
    bytes32 private immutable _keyHash;

    /// @notice Callback gas limit must not go over 2.5M as required by VRF
    uint32 private constant CALLBACK_GAS_LIMIT = 2_500_000;

    /// @notice The default is 3, but you can set this higher.
    uint16 private constant REQUEST_CONFIRMATIONS = 3;

    // For this example, retrieve 2 random values in one request.
    // Cannot exceed VRFCoordinatorV2.MAX_NUM_WORDS.
    uint32 constant NUM_WORDS = 1;

    /// @notice Address of the contract owner
    address private _owner;

    /// @notice The admin wallet that holds the unclaimed tokens.
    address private _administrator;

    /// @notice The requester contracts that will ask for random numbers.
    address[] private _requesters;

    // Array to track randomization requests
    mapping(uint256 => Params) public requests;

    event ReturnedRandomWord(
        uint256 randomWord,
        uint256 requestId,
        Params params
    );

    event RequesterAdded(address requester);
    event RequesterRemoved(address requester);

    error NewRequesterIsZeroAddress();
    error OnlyOwner();
    error OnlyOwnerOrRequester();

    /**
     * @notice Constructor inherits VRFConsumerBaseV2
     *
     * @param subscriptionId - the subscription ID that this contract uses for funding requests
     * @param vrfCoordinator - coordinator, check https://docs.chain.link/docs/vrf-contracts/#configurations
     * @param keyHash - the gas lane to use, which specifies the maximum gas price to bump to
     */
    constructor(
        uint64 subscriptionId,
        address vrfCoordinator,
        bytes32 keyHash
    ) VRFConsumerBaseV2(vrfCoordinator) {
        COORDINATOR = VRFCoordinatorV2Interface(vrfCoordinator);
        _keyHash = keyHash;
        _owner = msg.sender;
        _subscriptionId = subscriptionId;
    }

    /**
     * @notice Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        if (msg.sender != _owner) {
            revert OnlyOwner();
        }
        _;
    }

    /**
     * @notice Throws if called by any account other than the owner or requester contract.
     */
    modifier onlyOwnerOrRequester() virtual {
        if (msg.sender != _owner) {
            if (!requesterIsAdded(msg.sender)) {
                revert OnlyOwnerOrRequester();
            }
        }
        _;
    }

    function requesterIsAdded(address requester) public view returns (bool) {
        for (uint256 i = 0; i < _requesters.length; i++) {
            if (_requesters[i] == requester) {
                return true;
            }
        }
        return false;
    }

    /**
     * @notice Add a requester contract to the admin array.
     *
     * @param requester The address of the requester.
     */
    function addRequester(address requester) external onlyOwner {
        if (requester == address(0)) {
            revert NewRequesterIsZeroAddress();
        }

        if (requesterIsAdded(requester)) {
            return;
        }

        _requesters.push(requester);
        emit RequesterAdded(requester);
    }

    /**
     * @notice Remove a requester contract from the admin array.
     *
     * @param requester The address of the requester.
     */
    function removeRequester(address requester) external onlyOwner {
        address[] storage requesters = _requesters;
        for (uint256 i = 0; i < requesters.length; i++) {
            if (requesters[i] == requester) {
                address last = requesters[requesters.length - 1];
                requesters[i] = last;
                requesters.pop();
                break;
            }
        }

        emit RequesterRemoved(requester);
    }

    /**
     * @notice Makes a random request
     * Assumes the subscription is funded sufficiently; "Words" refers to unit of data in Computer Science
     *
     * @param partnerContract the address of the partner contract
     * @param totalEntries the total number of entries to randomize
     * @param totalSelections the number of selections to return
     * @param title the title used to write the logs
     */
    function requestRandomWords(
        address partnerContract,
        uint32 totalEntries,
        uint32 totalSelections,
        string calldata title
    ) external onlyOwnerOrRequester {
        // Will revert if subscription is not set and funded.
        uint256 requestId = COORDINATOR.requestRandomWords(
            _keyHash,
            _subscriptionId,
            REQUEST_CONFIRMATIONS,
            CALLBACK_GAS_LIMIT,
            NUM_WORDS
        );

        requests[requestId] = Params(
            partnerContract,
            totalEntries,
            totalSelections,
            title
        );
    }

    /**
     * @notice Callback function used by VRF Coordinator
     *
     * @param requestId - the requestId from the VRF Coordinator
     * @param randomWords - array of random results from VRF Coordinator
     */
    function fulfillRandomWords(
        uint256 requestId,
        uint256[] memory randomWords
    ) internal override {
        emit ReturnedRandomWord(randomWords[0], requestId, requests[requestId]);
    }

    /**
     * @notice Gets the subscription ID set up by VRF
     */
    function getSubscriptionId() public view returns (uint64) {
        return _subscriptionId;
    }
}