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

import { MerkleProof } from "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";

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

/// @title MerkleProofChecker
/// @notice Merkle validator.
/// @dev Extends BaseChecker to implement Merkle validation logic.
contract MerkleProofChecker is BaseChecker {
    // the merkle tree root
    bytes32 public root;

    /// @notice custom errors
    error InvalidProof();
    error InvalidRoot();

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

        bytes memory data = _getAppendedBytes();
        bytes32 _root = abi.decode(data, (bytes32));

        if (_root == bytes32(0)) {
            revert InvalidRoot();
        }

        root = _root;
    }

    /// @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);

        bytes32[] memory proof = abi.decode(evidence, (bytes32[]));

        // get the leaf
        bytes32 leaf = keccak256(bytes.concat(keccak256(abi.encode(subject))));

        // check the proof
        if (!MerkleProof.verify(proof, root, leaf)) {
            revert InvalidProof();
        }

        return true;
    }
}