디사이퍼

Exchange.sol

// SPDX-License-Identifier: MIT
pragma solidity >= 0.8.0;


import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";


contract Exchange is ERC20 {
    IERC20 public token;


    constructor(address _token) ERC20("Uniswap V1", "UNI-V1") {
        token = IERC20(_token);
    }


    function getInputPrice(
        uint input_amount,
        uint input_reserve,
        uint output_reserve
    ) public pure returns (uint output_amount) {
        uint numerator = output_reserve * input_amount;
        uint denominator = input_amount + input_reserve;
        output_amount = numerator / denominator;
        return output_amount;
    }


    function ethToTokenInput(
        uint eth_sold,
        uint min_tokens,
        uint deadline,
        address buyer,
        address recipient
    ) public payable returns (uint tokens_bought) {
        tokens_bought = getInputPrice(
            eth_sold,
            address(this).balance - eth_sold,
            token.balanceOf(address(this)) 
        ); 
        token.transfer(recipient, tokens_bought);
    }


    function ethToTokenSwapInput(
        uint min_tokens,
        uint deadline
    ) public payable returns (uint) {
        return ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, msg.sender);
    }


    function ethToTokenTransferInput(
        uint min_tokens,
        uint deadline,
        address recipient
    ) public payable returns (uint) {
        return ethToTokenInput(msg.value, min_tokens, deadline, msg.sender, recipient);
    }


    function addLiquidity(
        uint min_liquidity,
        uint max_tokens,
        uint deadline
    ) public payable returns (uint liquidity_minted) {
        if (totalSupply() > 0) {
            uint token_amount = msg.value * token.balanceOf(address(this)) / (address(this).balance - msg.value);
            token.transferFrom(msg.sender, address(this), token_amount);
            liquidity_minted = msg.value * balanceOf(address(this)) / (address(this).balance - msg.value);
            _mint(msg.sender, liquidity_minted);

        } else {
            token.transferFrom(msg.sender, address(this), max_tokens);
            _mint(msg.sender, msg.value);
        }
    }
}