Auction contract

auction/.env.example

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+ALCHEMY_API_KEY=
+ROPSTEN_PRIVATE_KEY=

auction/.gitignore

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+node_modules
+.env
+
+#Hardhat files
+cache
+artifacts

auction/contracts/Auction.sol

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+// SPDX-License-Identifier: GPL-3.0
+
+pragma solidity ^0.8.7;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "@openzeppelin/contracts/utils/math/Math.sol";
+
+contract Auction is Ownable {
+    uint256 constant BLOCKS_IN_A_WEEK = 40320;
+
+    enum State {
+        STARTED,
+        RUNNING,
+        ENDED,
+        CANCELED
+    }
+
+    uint256 public startBlock;
+    uint256 public endBlock;
+    string public ipfsHash;
+    State public state;
+    uint256 public highestBindingBid;
+    address payable public highestBidder;
+    mapping(address => uint256) public bids;
+    uint256 bidIncrement;
+
+    constructor(address owner) {
+        state = State.RUNNING;
+        startBlock = block.number;
+        endBlock = startBlock + BLOCKS_IN_A_WEEK;
+        ipfsHash = "";
+        bidIncrement = 100;
+        transferOwnership(owner);
+    }
+
+    modifier notOwner() {
+        require(msg.sender != owner(), "not callable by owner");
+        _;
+    }
+
+    modifier afterStart() {
+        require(block.number >= startBlock, "auction didnt start yet");
+        _;
+    }
+
+    modifier beforeEnd() {
+        require(block.number <= endBlock, "auction already ended");
+        _;
+    }
+
+    function cancel() public onlyOwner {
+        state = State.CANCELED;
+    }
+
+    function placeBid() public payable notOwner afterStart beforeEnd {
+        require(state == State.RUNNING, "auction is not running");
+        require(msg.value >= 100, "minimum bid is 100 wei");
+
+        uint256 currentSenderBid = bids[msg.sender] + msg.value;
+        require(currentSenderBid > highestBindingBid);
+
+        bids[msg.sender] = currentSenderBid;
+
+        uint256 currentHighestBid = bids[highestBidder];
+        if (currentSenderBid <= currentHighestBid) {
+            highestBindingBid = Math.min(
+                currentSenderBid + bidIncrement,
+                currentHighestBid
+            );
+        } else {
+            highestBindingBid = Math.min(
+                currentSenderBid,
+                currentHighestBid + bidIncrement
+            );
+            highestBidder = payable(msg.sender);
+        }
+    }
+
+    function finalize() public {
+        require(state == State.CANCELED || block.number > endBlock);
+        require(msg.sender == owner() || bids[msg.sender] > 0);
+
+        address payable recipient;
+        uint256 value;
+
+        if (state == State.CANCELED) {
+            recipient = payable(msg.sender);
+            value = bids[msg.sender];
+        } else {
+            if (msg.sender == payable(owner())) {
+                recipient = payable(owner());
+                value = highestBindingBid;
+            } else {
+                if (msg.sender == highestBidder) {
+                    recipient = highestBidder;
+                    value = bids[highestBidder] - highestBindingBid;
+                } else {
+                    recipient = payable(msg.sender);
+                }
+            }
+        }
+
+        bids[recipient] = 0;
+        recipient.transfer(value);
+    }
+}

auction/contracts/AuctionCreator.sol

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+// SPDX-License-Identifier: GPL-3.0
+
+pragma solidity ^0.8.7;
+
+import "@openzeppelin/contracts/access/Ownable.sol";
+import "./Auction.sol";
+
+contract AuctionCreator is Ownable {
+    Auction[] public auctions;
+
+    function createAuction() public {
+        Auction auction = new Auction(msg.sender);
+        auctions.push(auction);
+    }
+}

auction/hardhat.config.ts

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+import { task } from "hardhat/config";
+import "@nomiclabs/hardhat-waffle";
+
+import dotenv from 'dotenv'
+dotenv.config()
+
+// This is a sample Hardhat task. To learn how to create your own go to
+// https://hardhat.org/guides/create-task.html
+task("accounts", "Prints the list of accounts", async (args, hre) => {
+  const accounts = await hre.ethers.getSigners();
+
+  for (const account of accounts) {
+    console.log(await account.address);
+  }
+});
+
+// You need to export an object to set up your config
+// Go to https://hardhat.org/config/ to learn more
+
+export default {
+  solidity: "0.8.7",
+  networks: {
+    ropsten: {
+      url: `https://eth-ropsten.alchemyapi.io/v2/${process.env.ALCHEMY_API_KEY}`,
+      accounts: [`0x${process.env.ROPSTEN_PRIVATE_KEY}`],
+    },
+  },
+};