// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import {IAny2EVMMessageReceiver} from "../interfaces/IAny2EVMMessageReceiver.sol";

import {Client} from "../libraries/Client.sol";

import {IERC165} from "../../vendor/openzeppelin-solidity/v5.0.2/contracts/utils/introspection/IERC165.sol";

/// @title CCIPReceiver - Base contract for CCIP applications that can receive messages.
abstract contract CCIPReceiver is IAny2EVMMessageReceiver, IERC165 {
  address internal immutable i_ccipRouter;

  constructor(address router) {
    if (router == address(0)) revert InvalidRouter(address(0));
    i_ccipRouter = router;
  }

  /// @notice IERC165 supports an interfaceId
  /// @param interfaceId The interfaceId to check
  /// @return true if the interfaceId is supported
  /// @dev Should indicate whether the contract implements IAny2EVMMessageReceiver
  /// e.g. return interfaceId == type(IAny2EVMMessageReceiver).interfaceId || interfaceId == type(IERC165).interfaceId
  /// This allows CCIP to check if ccipReceive is available before calling it.
  /// If this returns false or reverts, only tokens are transferred to the receiver.
  /// If this returns true, tokens are transferred and ccipReceive is called atomically.
  /// Additionally, if the receiver address does not have code associated with
  /// it at the time of execution (EXTCODESIZE returns 0), only tokens will be transferred.
  function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
    return interfaceId == type(IAny2EVMMessageReceiver).interfaceId || interfaceId == type(IERC165).interfaceId;
  }

  /// @inheritdoc IAny2EVMMessageReceiver
  function ccipReceive(Client.Any2EVMMessage calldata message) external virtual override onlyRouter {
    _ccipReceive(message);
  }

  /// @notice Override this function in your implementation.
  /// @param message Any2EVMMessage
  function _ccipReceive(Client.Any2EVMMessage memory message) internal virtual;

  /////////////////////////////////////////////////////////////////////
  // Plumbing
  /////////////////////////////////////////////////////////////////////

  /// @notice Return the current router
  /// @return CCIP router address
  function getRouter() public view virtual returns (address) {
    return address(i_ccipRouter);
  }

  error InvalidRouter(address router);

  /// @dev only calls from the set router are accepted.
  modifier onlyRouter() {
    if (msg.sender != getRouter()) revert InvalidRouter(msg.sender);
    _;
  }
}