// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import { BaseChecker } from "../../checker/BaseChecker.sol";
import { IHats } from "./IHats.sol";

/// @title HatsChecker
/// @notice Hats validator.
/// @dev Extends BaseChecker to implement Hats validation logic.
contract HatsChecker is BaseChecker {
    /// @notice The Hats Protocol contract address
    IHats public hats;

    /// @notice Tracks hats that users must wear to be eligible to enforce
    mapping(uint256 => bool) public criterionHats;

    /// @notice Custom errors
    error NotCriterionHat();
    error NotWearingCriterionHat();

    /// @notice Initializes the contract.
    function _initialize() internal override {
        super._initialize();

        bytes memory data = _getAppendedBytes();
        (address _hats, uint256[] memory _criterionHats) = abi.decode(data, (address, uint256[]));

        hats = IHats(_hats);

        // add the criterion hats
        for (uint256 i = 0; i < _criterionHats.length; i++) {
            criterionHats[_criterionHats[i]] = true;
        }
    }

    /// @notice Throws errors if evidence and subject are not valid.
    /// @param subject Address to validate.
    /// @param evidence Encoded data used for validation.
    /// @return Boolean indicating whether the subject passes the check.
    function _check(address subject, bytes calldata evidence) internal view override returns (bool) {
        super._check(subject, evidence);

        // decode the _data as a hat
        uint256 hat = abi.decode(evidence, (uint256));

        // the hat must be set as a criterion hat
        if (!criterionHats[hat]) {
            revert NotCriterionHat();
        }

        // subject must be wearing the criterion hat
        if (!hats.isWearerOfHat(subject, hat)) {
            revert NotWearingCriterionHat();
        }

        return true;
    }
}