Create DEXContract.sol

contracts/DEXContract.sol

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+pragma solidity ^0.8.0;
+
+import "https://github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/SafeERC20.sol";
+
+contract DEXContract {
+    using SafeERC20 for IERC20;
+
+    // Struct to represent a trade
+    struct Trade {
+        address trader;
+        address tokenIn;
+        address tokenOut;
+        uint amountIn;
+        uint amountOut;
+        uint timestamp;
+    }
+
+    // Mapping of token pairs to their exchange rates
+    mapping(address => mapping(address => uint)) public exchangeRates;
+
+    // Array to store trades
+    Trade[] public trades;
+
+    // Event emitted when a trade is executed
+    event TradeExecuted(address indexed trader, address tokenIn, address tokenOut, uint amountIn, uint amountOut);
+
+    // Function to set the exchange rate for a token pair
+    function setExchangeRate(address _tokenIn, address _tokenOut, uint _rate) public {
+        exchangeRates[_tokenIn][_tokenOut] = _rate;
+    }
+
+    // Function to execute a trade
+    function trade(address _tokenIn, address _tokenOut, uint _amountIn) public {
+        uint rate = exchangeRates[_tokenIn][_tokenOut];
+        require(rate > 0, "Exchange rate not set");
+
+        uint amountOut = _amountIn * rate / 1e18; // Assuming rate is in 18 decimals
+
+        // Transfer tokens from the trader to the contract
+        IERC20(_tokenIn).safeTransferFrom(msg.sender, address(this), _amountIn);
+        // Transfer tokens from the contract to the trader
+        IERC20(_tokenOut).safeTransfer(msg.sender, amountOut);
+
+        // Record the trade
+        trades.push(Trade(msg.sender, _tokenIn, _tokenOut, _amountIn, amountOut, block.timestamp));
+
+        // Emit the TradeExecuted event
+        emit TradeExecuted(msg.sender, _tokenIn, _tokenOut, _amountIn, amountOut);
+    }
+
+    // Function to get the details of a trade
+    function getTrade(uint _index) public view returns (Trade memory) {
+        return trades[_index];
+    }
+
+    // Function to get the number of trades
+    function getTradeCount() public view returns (uint) {
+        return trades.length;
+    }
+}