CloseAuctionServlet.java

package com.seller;

import java.io.IOException;
import java.sql.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;

@WebServlet("/closeAuction")
public class CloseAuctionServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws IOException {

        int auctionId = Integer.parseInt(request.getParameter("auctionId"));

        try {
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection conn = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/login_app", "root", "Pallavi@1000");

            PreparedStatement aStmt = conn.prepareStatement(
                "SELECT minPrice, status FROM T_Auction_isAuctioned WHERE auction_id = ?"
            );
            aStmt.setInt(1, auctionId);
            ResultSet aRs = aStmt.executeQuery();

            if (!aRs.next()) {
                response.getWriter().println("Auction not found.");
                return;
            }

            double minPrice = aRs.getDouble("minPrice");
            String status   = aRs.getString("status");


            if (!"active".equalsIgnoreCase(status)) {
                response.sendRedirect("sellerAuctionList.jsp");
                return;
            }

            PreparedStatement bStmt = conn.prepareStatement(
                "SELECT user_id, bid_amount " +
                "FROM T_BidsOn_Bid_ItemBid " +
                "WHERE auction_id = ? " +
                "ORDER BY bid_amount DESC LIMIT 1"
            );
            bStmt.setInt(1, auctionId);
            ResultSet bRs = bStmt.executeQuery();

            Integer winnerId  = null;
            Double highestBid = null;

            if (bRs.next()) {
                winnerId  = bRs.getInt("user_id");
                highestBid = bRs.getDouble("bid_amount");
            }

            String finalStatus;
            if (winnerId == null) {
                finalStatus = "expired";
            } else if (highestBid < minPrice) {
                finalStatus = "failed";
                winnerId = null;  
            } else {
                finalStatus = "sold";
            }

            PreparedStatement update = conn.prepareStatement(
                "UPDATE T_Auction_isAuctioned " +
                "SET status = ?, winner_id = ? " +
                "WHERE auction_id = ?"
            );
            update.setString(1, finalStatus);

            if (winnerId == null) {
                update.setNull(2, Types.INTEGER);
            } else {
                update.setInt(2, winnerId);
            }

            update.setInt(3, auctionId);
            update.executeUpdate();

            if ("sold".equals(finalStatus) && winnerId != null) {
                PreparedStatement notify = conn.prepareStatement(
                    "INSERT INTO alerts (user_id, message) VALUES (?, ?)"
                );
                notify.setInt(1, winnerId);
                notify.setString(2,
                    "Congratulations! You won auction #" + auctionId +
                    " with a bid of $" + highestBid + "!");
                notify.executeUpdate();
            }

            response.sendRedirect("sellerAuctionList.jsp");

        } catch (Exception e) {
            e.printStackTrace(response.getWriter());
        }
    }
}