Simple DEX smart contract for swapping ETH and an ERC20 token

simple_dex.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "./TrainingToken.sol";
contract DEX {
   TrainingToken token;

   address public tokenAddress;   
   
   event TokensBought(uint256 amount,uint256 etherAmount,address _buyer);
   event TokensSold(uint256 amount,uint256 etherAmount,address _seller);

   constructor(address _token) payable{
      require(msg.value > 0 , "You have to at least deposit something to start a DEX");
      tokenAddress = _token;
      token = TrainingToken(address(tokenAddress));
    }

    //ETH required to buy all tokens in Pool. price is calculated based on constant product formula AMM
    function etherPrice() public view returns (uint256) {
        return token.balanceOf(address(this))/address(this).balance;
    }

    function buy() payable public {
        uint256 amountTobuy = msg.value;
        uint256 price = etherPrice();
        uint256 dexBalance = token.balanceOf(address(this));
        require(amountTobuy > 0, "You need to send some Ether");
        require(amountTobuy*price <= dexBalance, "Not enough tokens in the reserve");
        token.transfer(msg.sender, amountTobuy*price);

        emit TokensBought(amountTobuy*price,amountTobuy,msg.sender);
    }   
   
    function sell(uint256 amount) public {
      require(amount > 0, "You need to sell at least some tokens");
      uint256 approvedAmt = token.allowance(msg.sender, address(this));
      require(approvedAmt >= amount, "Check the token allowance");

      uint256 price = etherPrice();
      token.transferFrom(msg.sender, payable(address(this)), amount);
      payable(msg.sender).transfer(amount/price);

      emit TokensSold(amount/price,amount,msg.sender);
   }}