https://github.com/edakturk14/buidlbase-berlin

BuidlBase Berlin Workshop - SpeedRunEthereum Token Vendor
https://github.com/edakturk14/buidlbase-berlin

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BuidlBase Berlin Workshop - SpeedRunEthereum Token Vendor

• Host: GitHub
• URL: https://github.com/edakturk14/buidlbase-berlin
• Owner: edakturk14
• Created: 2024-05-21T09:09:36.000Z (8 months ago)
• Default Branch: main
• Last Pushed: 2024-05-21T10:51:50.000Z (8 months ago)
• Last Synced: 2024-10-22T20:39:04.372Z (3 months ago)
• Size: 1.95 KB
• Stars: 1
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# BuidlBase-Berlin

BuidlBase Berlin Workshop - SpeedRunEthereum Token Vendor

A token vendor is a machine from where you can buy and sell tokens. You can buy tokens with ETH or sell your tokens in exchange for ETH.

The project uses ERC20 token. Some key learnings:

- YourToken.sol inherits this openzepplin contract

balanceOf allows you to check the balance of the address directly in ERC 20 :-)

- ERC 20 has a transfer() function; many of the functions are already there.

- ERC 20 has an approve patter that you need to apply before spending tokens. 

1. Go to speedrunethereum.com, we'll be doing the Token Vendor challange. 

https://speedrunethereum.com/challenge/token-vendor

2. Setup 

Download the challenge to your computer and install dependencies by running:

```

git clone https://github.com/scaffold-eth/se-2-challenges.git challenge-2-token-vendor

cd challenge-2-token-vendor

git checkout challenge-2-token-vendor

yarn install

```

In the same terminal, start your local network (a blockchain emulator in your computer):

```

yarn chain 

```

In a new terminal window, 🛰 deploy your contract (locally):

```

cd challenge-2-token-vendor

yarn deploy

```

In a third terminal window, start your 📱 frontend:

```

cd challenge-2-token-vendor

yarn start

```

Open http://localhost:3000 to see the app.

3. Edit YourToken.sol -- Change the address to mint the token to your local address

```

contract YourToken is ERC20 {

	constructor() ERC20("Gold", "GLD") {

		_mint(msg.sender, 1000 * 10 ** 18);

	}

}

```

```

yarn deploy --reset 

```

4. Edit the Vendor.sol contract

```

pragma solidity 0.8.4; //Do not change the solidity version as it negativly impacts submission grading

// SPDX-License-Identifier: MIT

import "@openzeppelin/contracts/access/Ownable.sol";

import "./YourToken.sol";

contract Vendor is Ownable {

	event BuyTokens(address buyer, uint256 amountOfETH, uint256 amountOfTokens);

	event SellTokens(address seller, uint256 amountOfTokens);

	YourToken public yourToken;

	uint256 public constant tokensPerEth = 1;

	constructor(address tokenAddress) {

		yourToken = YourToken(tokenAddress);

	}

	// ToDo: create a payable buyTokens() function:

	function buyTokens() public payable {

		uint256 tokenAmount = msg.value * tokensPerEth;

		yourToken.transfer(msg.sender, tokenAmount);

		emit BuyTokens(msg.sender, msg.value, tokenAmount);

	}

	// ToDo: create a withdraw() function that lets the owner withdraw ETH

	function withdraw() public onlyOwner {

		(bool success, ) = payable(address(owner())).call{

			value: address(this).balance

		}("");

	}

	// ToDo: create a sellTokens(uint256 _amount) function:

	function sellTokens(uint256 _amount) public {

		// Ensure the amount is greater than zero

		require(_amount > 0, "Amount must be greater than zero");

		// Call the allowance function on the token contract

		uint256 allowedAmount = yourToken.allowance(msg.sender, address(this));

		require(

			allowedAmount >= _amount,

			"You need to approve the tokens first"

		);

		// Transfer the tokens from the sender to this contract

		yourToken.transferFrom(msg.sender, address(this), _amount);

		// Emit the SellTokens event

		emit SellTokens(msg.sender, _amount);

	}

}

```