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

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

/// @title AnonAadhaarChecker
/// @notice AnonAadhaar validator.
/// @dev Extends BaseChecker to implement Zupass validation logic.
contract AnonAadhaarChecker is BaseChecker {
    /// @notice The AnonAadhaar contract
    IAnonAadhaar public anonAadhaarContract;

    /// @notice The nullifier seed
    uint256 public nullifierSeed;

    /// @notice Errors
    error InvalidProof();
    error InvalidSignal();
    error InvalidNullifierSeed();

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

        bytes memory data = _getAppendedBytes();
        (address _anonAadhaarVerifier, uint256 _nullifierSeed) = abi.decode(data, (address, uint256));

        anonAadhaarContract = IAnonAadhaar(_anonAadhaarVerifier);
        nullifierSeed = _nullifierSeed;
    }

    /// @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 argument
        (
            uint256 providedNullifierSeed,
            uint256 nullifier,
            uint256 timestamp,
            uint256 signal,
            uint256[4] memory revealArray,
            uint256[8] memory groth16Proof
        ) = abi.decode(evidence, (uint256, uint256, uint256, uint256, uint256[4], uint256[8]));

        // ensure that the provided nullifier seed matches the stored nullifier seed
        if (providedNullifierSeed != nullifierSeed) {
            revert InvalidNullifierSeed();
        }

        // ensure that the signal is correct
        if (signal != uint256(uint160(subject))) {
            revert InvalidSignal();
        }

        // check if the proof validates
        if (
            !anonAadhaarContract.verifyAnonAadhaarProof(
                providedNullifierSeed,
                nullifier,
                timestamp,
                signal,
                revealArray,
                groth16Proof
            )
        ) {
            revert InvalidProof();
        }

        return true;
    }
}