// SPDX-License-Identifier: MIT
pragma solidity 0.8.37;

/// @title BDAGBurnVault
/// @notice Publicly and permanently locks voluntarily submitted native BDAG.
/// @dev The contract deliberately has no owner, admin, upgrade, call, or withdrawal path.
contract BDAGBurnVault {
    uint256 public constant BDAG_CHAIN_ID = 1404;

    error WrongChainId(uint256 detectedChainId);
    error ZeroValue();
    error ZeroReference();
    error UnsupportedCall();

    event NativeBDAGPermanentlyLocked(
        address indexed sender,
        bytes32 indexed burnReference,
        uint256 amount,
        uint256 newLockedBalance
    );

    constructor() {
        if (block.chainid != BDAG_CHAIN_ID) {
            revert WrongChainId(block.chainid);
        }
    }

    /// @notice Accepts a voluntary direct native-BDAG transfer.
    /// @dev A zero reference identifies a plain wallet transfer.
    receive() external payable {
        _lock(bytes32(0));
    }

    /// @notice Permanently locks native BDAG and publishes a caller-supplied reference.
    /// @dev The optional reference is attribution metadata, not authorization or
    ///      proof of identity. The general public interface uses a direct transfer.
    function burn(bytes32 burnReference) external payable {
        if (burnReference == bytes32(0)) revert ZeroReference();
        _lock(burnReference);
    }

    /// @notice Rejects value transfers that contain calldata and all unknown calls.
    fallback() external payable {
        revert UnsupportedCall();
    }

    /// @notice Returns the authoritative amount of native BDAG locked at this address.
    function lockedBalance() external view returns (uint256) {
        return address(this).balance;
    }

    function _lock(bytes32 burnReference) private {
        if (msg.value == 0) revert ZeroValue();
        emit NativeBDAGPermanentlyLocked(
            msg.sender,
            burnReference,
            msg.value,
            address(this).balance
        );
    }
}