Bank.sol

pragma solidity ^0.8.0;


import "@openzeppelin/contracts/token/ERC20/extensions/draft-IERC20Permit.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

import "@openzeppelin/contracts/interfaces/IERC1820Registry.sol";

interface TokenRecipient {
    function tokensReceived(address sender, uint amount) external returns (bool);
}

contract Bank is TokenRecipient {
    mapping(address => uint) public deposited;
    address public immutable token;

      // keccak256("ERC777TokensRecipient")
    bytes32 constant private TOKENS_RECIPIENT_INTERFACE_HASH =
      0xb281fc8c12954d22544db45de3159a39272895b169a852b314f9cc762e44c53b;

    IERC1820Registry private erc1820 = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);

    constructor(address _token) {
        token = _token;
        //erc1820.setInterfaceImplementer(address(this), TOKENS_RECIPIENT_INTERFACE_HASH, address(this));
        
    }


    function tokensReceived(address sender, uint amount) external returns (bool) {
        require(msg.sender == token, "invalid");
        deposited[sender] += amount;
        return true;
    }

    function deposit(address user, uint amount) public {
        IERC20(token).transferFrom(msg.sender, address(this), amount);
        deposited[user] += amount;
    }


    function permitDeposit(address user, uint amount, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
        IERC20Permit(token).permit(msg.sender, address(this), amount, deadline, v, r, s);
        deposit(user, amount);
    }


// 收款时被回调
  function tokensReceived(
      address operator,
      address from,
      address to,
      uint amount,
      bytes calldata userData,
      bytes calldata operatorData
  ) external {
      require(msg.sender == token, "invalid");
        deposited[from] += amount;
  }

}