After viva

hello.sol

@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+contract Auction {
+    // State variables
+    address public owner;
+    uint256 public startTimestamp;
+    uint256 public endTimestamp;
+    address public highestBidder;
+    uint256 public highestBindingBid;
+
+    mapping(address => uint256) public bids;
+
+    // Modifiers
+    modifier onlyOwner() {
+        require(msg.sender == owner, "Not the owner");
+        _;
+    }
+
+    modifier onlyBeforeEnd() {
+        require(block.timestamp < endTimestamp, "Auction has already ended");
+        _;
+    }
+
+    modifier onlyAfterEnd() {
+        require(block.timestamp >= endTimestamp, "Auction has not ended yet");
+        _;
+    }
+
+    // Additional state variables
+    uint256 public previousHighestBid;
+    uint256 public numberOfBids;
+    uint256 public increment;
+
+    // Constructor
+    constructor(uint256 minutesDuration) {
+        owner = msg.sender;
+        startTimestamp = block.timestamp;
+        endTimestamp = startTimestamp + (minutesDuration * 1 minutes);
+    }
+
+    // Bid function
+  // Add a state variable to store addresses with the same value
+// Add a state variable to store addresses with the same value
+address[] private addressesWithSameValueArray;
+
+// Update the placeBid function
+function placeBid() external payable onlyBeforeEnd {
+    require(msg.sender != owner, "Owner cannot bid.");
+    require(msg.value > 0, "Bid amount must be greater than 0");
+
+    if (msg.value >= highestBindingBid) {
+        if (msg.value == highestBindingBid) {
+            // Add the bidder's address to the array
+            addressesWithSameValueArray.push(msg.sender);
+        }
+
+        // Update highestBid and highestBidder
+        previousHighestBid = highestBindingBid;
+        highestBindingBid = msg.value;
+        highestBidder = msg.sender;
+    }
+
+    // Update bids mapping for the bidder
+    bids[msg.sender] = msg.value;
+
+    // Increment the number of bids
+    numberOfBids++;
+}
+
+// Add a function to randomly select a winner among bidders with the same value
+function getRandomBidderWithSameValue() internal view returns (address) {
+    if (addressesWithSameValueArray.length > 0) {
+        uint256 randomIndex = uint256(keccak256(abi.encodePacked(blockhash(block.number - 1), msg.sender))) % addressesWithSameValueArray.length;
+        return addressesWithSameValueArray[randomIndex];
+    }
+
+    return address(0);
+}
+function finalizeAuction() external onlyOwner onlyAfterEnd {
+    require(highestBidder != address(0), "No bidders");
+
+    uint256 maxIncrement = ((highestBindingBid - previousHighestBid) / 2);
+
+    highestBindingBid = previousHighestBid + maxIncrement;
+
+    for (uint256 i = 0; i < addressesWithSameValueArray.length; i++) {
+        payable(addressesWithSameValueArray[i]).transfer(bids[addressesWithSameValueArray[i]]);
+    }
+
+    payable(highestBidder).transfer(highestBindingBid);
+}
+
+    // Withdraw funds function
+    function withdraw() external onlyAfterEnd {
+        uint256 amount = bids[msg.sender];
+        require(amount > 0, "No funds to withdraw");
+        bids[msg.sender] = 0;
+
+        if (msg.sender == highestBidder) {
+            // Deduct the highestBindingBid from the withdrawal amount for the highest bidder
+            amount = amount - highestBindingBid;
+            require(amount >= 0, "Withdrawal amount cannot be negative");
+        }
+
+        // Transfer funds to the bidder
+        payable(msg.sender).transfer(amount);
+    }
+
+    // Cancel auction function
+    function cancelAuction() public onlyOwner onlyBeforeEnd {
+        // End the auction prematurely
+        endTimestamp = block.timestamp;
+
+        // Reset auction state
+        highestBidder = address(0);
+        highestBindingBid = 0;
+    }
+}