// SPDX-License-Identifier: MIT
pragma solidity 0.8.26;
import {ERC20} from '@openzeppelin/contracts/token/ERC20/ERC20.sol';
import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
import {SafeERC20} from '@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol';

/// @notice Faucet-only test token, with no economic value or relationship to Circle / WETH issuers.
contract DemoToken is ERC20 {
    address public immutable faucet;
    uint8 private immutable precision;
    constructor(string memory name_,string memory symbol_,uint8 decimals_) ERC20(name_,symbol_){faucet=msg.sender;precision=decimals_;}
    function decimals() public view override returns(uint8){return precision;}
    function mint(address to,uint256 amount) external {require(msg.sender==faucet,'faucet only');_mint(to,amount);}
}

/// @notice Fixed illustrative rate: 3000 demo USDC per demo WETH. Not a DEX, oracle or bridge.
contract DemoSwap {
    using SafeERC20 for IERC20;
    IERC20 public immutable input;
    IERC20 public immutable output;
    address public immutable deployer;
    address public vault;
    constructor(address input_,address output_){input=IERC20(input_);output=IERC20(output_);deployer=msg.sender;}
    function setVault(address v) external {require(msg.sender==deployer&&vault==address(0)&&v.code.length>0,'locked');vault=v;}
    function swap(uint256 amount,address recipient) external returns(uint256 out){
        require(msg.sender==vault,'vault only');out=amount*1e12/3000;output.safeTransfer(recipient,out);
    }
}