// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

/// @notice Minimal VRF v2 (subscription) coordinator surface, as run by Plugin on XDC.
interface IVRFCoordinatorV2Like {
    function requestRandomWords(
        bytes32 keyHash,
        uint64 subId,
        uint16 minimumRequestConfirmations,
        uint32 callbackGasLimit,
        uint32 numWords
    ) external returns (uint256 requestId);
}

/// @title VRFv2ConsumerExperimental  —  EXPERIMENTAL, not promoted
/// @notice Targets ONLY "VRFCoordinatorV2 1.0.0", the version Plugin has deployed on XDC mainnet
///         (typeAndVersion() read on 2026-10-21 at 0xCc017FEe2fbD6722168c07418D9dD6A2509E10B4;
///         v2.5 struct-based requestRandomWords selector absent). The coordinator showed no
///         events for ~30 days, so treat as experimental.
/// @dev Request is owner-gated to stop subscription draining. Clean-room.
contract VRFv2ConsumerExperimental {
    IVRFCoordinatorV2Like public immutable coordinator;
    bytes32 public immutable keyHash;
    uint64 public immutable subId;
    address public immutable owner;
    uint16 public constant MIN_CONFIRMATIONS = 3;
    uint32 public constant CALLBACK_GAS = 200_000;

    mapping(uint256 => uint256[]) internal _words;
    mapping(uint256 => bool) public pending;
    uint256 public lastRequestId;

    error OnlyCoordinator(address caller);
    error OnlyOwner();
    error UnknownRequest(uint256 requestId);

    event Requested(uint256 indexed requestId);
    event Fulfilled(uint256 indexed requestId, uint256[] words);

    constructor(IVRFCoordinatorV2Like _coordinator, bytes32 _keyHash, uint64 _subId) {
        coordinator = _coordinator;
        keyHash = _keyHash;
        subId = _subId;
        owner = msg.sender;
    }

    function request(uint32 numWords) external returns (uint256 id) {
        if (msg.sender != owner) revert OnlyOwner();
        id = coordinator.requestRandomWords(keyHash, subId, MIN_CONFIRMATIONS, CALLBACK_GAS, numWords);
        pending[id] = true;
        lastRequestId = id;
        emit Requested(id);
    }

    /// @notice Callback entry point called by the coordinator.
    function rawFulfillRandomWords(uint256 requestId, uint256[] calldata words) external {
        if (msg.sender != address(coordinator)) revert OnlyCoordinator(msg.sender);
        if (!pending[requestId]) revert UnknownRequest(requestId);
        pending[requestId] = false;
        _words[requestId] = words;
        emit Fulfilled(requestId, words);
    }

    function randomWords(uint256 requestId) external view returns (uint256[] memory) {
        return _words[requestId];
    }
}