// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./Ownable.sol";
import "./ILayerZeroReceiver.sol";
import "./ILayerZeroEndpoint.sol";
import "./BytesLib.sol";

/*
 * a generic LzReceiver implementation
 */
abstract contract LzApp is Ownable, ILayerZeroReceiver {
    using BytesLib for bytes;

    // ua can not send payload larger than this by default, but it can be changed by the ua owner
    uint public constant DEFAULT_PAYLOAD_SIZE_LIMIT = 10000;

    ILayerZeroEndpoint public immutable lzEndpoint;
    mapping(uint16 => bytes) public trustedRemoteLookup;
    mapping(uint16 => mapping(uint16 => uint)) public minDstGasLookup;
    mapping(uint16 => uint) public payloadSizeLimitLookup;
    address public precrime;

    event SetPrecrime(address precrime);
    event SetTrustedRemote(uint16 _remoteChainId, bytes _path);
    event SetTrustedRemoteAddress(uint16 _remoteChainId, bytes _remoteAddress);
    event SetMinDstGas(uint16 _dstChainId, uint16 _type, uint _minDstGas);

    constructor(address _endpoint) {
        lzEndpoint = ILayerZeroEndpoint(_endpoint);
    }

    function lzReceive(
        uint16 _srcChainId,
        bytes calldata _srcAddress,
        uint64 _nonce,
        bytes calldata _payload
    ) public virtual override {
        // lzReceive must be called by the endpoint for security
        require(msg.sender == address(lzEndpoint), "LzApp: invalid endpoint caller");

        bytes memory trustedRemote = trustedRemoteLookup[_srcChainId];
        // if will still block the message pathway from (srcChainId, srcAddress). should not receive message from untrusted remote.
        require(
            _srcAddress.length == trustedRemote.length && trustedRemote.length > 0 && keccak256(_srcAddress) == keccak256(trustedRemote),
            "LzApp: invalid source sending contract"
        );

        _blockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
    }

    // abstract function - the default behaviour of LayerZero is blocking. See: NonblockingLzApp if you dont need to enforce ordered messaging
    function _blockingLzReceive(
        uint16 _srcChainId,
        bytes memory _srcAddress,
        uint64 _nonce,
        bytes memory _payload
    ) internal virtual;

    function _lzSend(
        uint16 _dstChainId,
        bytes memory _payload,
        address payable _refundAddress,
        address _zroPaymentAddress,
        bytes memory _adapterParams,
        uint _nativeFee
    ) internal virtual {
        bytes memory trustedRemote = trustedRemoteLookup[_dstChainId];
        require(trustedRemote.length != 0, "LzApp: destination chain is not a trusted source");
        _checkPayloadSize(_dstChainId, _payload.length);
        lzEndpoint.send{value: _nativeFee}(_dstChainId, trustedRemote, _payload, _refundAddress, _zroPaymentAddress, _adapterParams);
    }

    function _checkPayloadSize(uint16 _dstChainId, uint _payloadSize) internal view virtual {
        uint payloadSizeLimit = payloadSizeLimitLookup[_dstChainId];
        if (payloadSizeLimit == 0) {
            // use default if not set
            payloadSizeLimit = DEFAULT_PAYLOAD_SIZE_LIMIT;
        }
        require(_payloadSize <= payloadSizeLimit, "LzApp: payload size is too large");
    }

    //---------------------------UserApplication config----------------------------------------
    function getConfig(
        uint16 _version,
        uint16 _chainId,
        address,
        uint _configType
    ) external view returns (bytes memory) {
        return lzEndpoint.getConfig(_version, _chainId, address(this), _configType);
    }

    function getTrustedRemoteAddress(uint16 _remoteChainId) external view returns (bytes memory) {
        bytes memory path = trustedRemoteLookup[_remoteChainId];
        require(path.length != 0, "LzApp: no trusted path record");
        return path.slice(0, path.length - 20); // the last 20 bytes should be address(this)
    }

    //--------------------------- VIEW FUNCTION ----------------------------------------
    function isTrustedRemote(uint16 _srcChainId, bytes calldata _srcAddress) external view returns (bool) {
        bytes memory trustedSource = trustedRemoteLookup[_srcChainId];
        return keccak256(trustedSource) == keccak256(_srcAddress);
    }
}