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contracts...SimpleTokenSale.sol

// SPDX-License-Identifier: GPL-3.0

pragma solidity >=0.7.0 <0.9.0;

import "hardhat/console.sol";

import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol";
import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/extensions/ERC20Capped.sol";


// Simple tokens sale. Build an ERC20 with the above features that sells tokens at a conversion rate of 10,000 tokens to 1 ethereum. The total supply should be 22 million tokens.

contract SimpleTokenSaleERC20 is ERC20, ERC20Capped {
    uint private constant CAP_AMOUNT = 22_000_000;
    uint public constant TOKENS_PER_ETH = 10_000;
    
    constructor() ERC20("GLD", "GLD") ERC20Capped(CAP_AMOUNT) {
        _mint(address(this), CAP_AMOUNT);
    }

    event TokenPurchased(address from, uint amount);
    event TokenSold(address from, uint amount);

    function _mint(address to, uint256 amount) internal override(ERC20, ERC20Capped){
        super._mint(to, amount);
    }
 
    function buyToken() external payable {
        uint tokenAmount = (msg.value/10**18) * TOKENS_PER_ETH;
        require(tokenAmount > 0, "Funds not enough for secure atleast 1 GLD Token");
        _transfer(address(this), msg.sender, tokenAmount);
        
        emit TokenPurchased(msg.sender, tokenAmount);
    }

    function sellToken(uint tokenAmount) external returns(bool){
        uint ethAmount = (tokenAmount * 10**18)/TOKENS_PER_ETH ;
        console.log(ethAmount, address(this).balance);
        (bool success, ) = msg.sender.call{value:ethAmount}("");
        
        transfer(address(this), tokenAmount);
        
        emit TokenSold(msg.sender, tokenAmount);
                
        return success;
    }


}