package servlet.reader;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import javabean.Base;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

/**
 * Servlet implementation class Book
 */
@WebServlet("/reader/book")
public class Book extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		// 设置响应内容类型为JSON，字符编码为UTF-8
		resp.setContentType("application/json; charset=utf8");

		// 接收请求参数
		String limit = req.getParameter("limit"); // 每页显示的记录数
		String page = req.getParameter("page"); // 当前页码
		String condition = (String) req.getParameter("condition"); // 查询条件字段
		String conditionValue = (String) req.getParameter("conditionValue"); // 查询条件值
		String where = ""; // SQL查询条件字符串

		// 默认分页参数
		if (page == null) {
			page = "1";
		}
		if (limit == null) {
			limit = "10";
		}

		// 数据库连接和SQL语句准备
		Connection connection = null;
		PreparedStatement pstmt = null;
		PreparedStatement countPstmt = null;
		ResultSet resultSet = null;
		ResultSet countSet = null;
		String sql = "";
		String countSql = "";

		// 返回数据结构初始化
		int code = 1; // 状态码，1表示失败，0表示成功
		String msg = "无数据"; // 消息提示
		int count = 0; // 总记录数
		JSONObject jsonData = new JSONObject(); // 单条记录的JSON对象
		JSONArray jsonArray = new JSONArray(); // 所有记录的JSON数组
		JSONObject jsonResult = new JSONObject(); // 最终返回的JSON对象

		try {
			// 获取数据库连接
			connection = (Connection) Base.getConnection();
			sql = "select * from books ";
			// 根据条件拼接SQL查询语句
			if (condition != null && conditionValue != null && !condition.equals("") && !conditionValue.equals("")) {
				where = " where " + condition + " like '%" + conditionValue + "%' ";
				sql += where;
			}
			// 分页查询
			sql += " limit ?,?"; // 计算偏移量和限制数量
			pstmt = connection.prepareStatement(sql);
			pstmt.setInt(1, (Integer.parseInt(page) - 1) * Integer.parseInt(limit));
			pstmt.setInt(2, Integer.parseInt(limit));
			resultSet = pstmt.executeQuery();

			// 处理查询结果集
			while (resultSet.next()) {
				// 获取图书信息
				String library = resultSet.getString("library_id");
				String sortid = resultSet.getString("sort_id");
				jsonData.put("id", resultSet.getString("id"));
				jsonData.put("name", resultSet.getString("name"));
				jsonData.put("author", resultSet.getString("author"));
				jsonData.put("position", resultSet.getString("position"));
				jsonData.put("status", resultSet.getString("status"));
				jsonData.put("description", resultSet.getString("description"));

				// 获取图书馆名称
				String sql1 = "select * from library where ID =" + library;
				PreparedStatement pstmt1 = connection.prepareStatement(sql1);
				ResultSet rs1 = pstmt1.executeQuery();
				String lib = "";
				while (rs1.next()) {
					lib = rs1.getString("name");
				}
				jsonData.put("library_id", lib);

				// 获取分类名称
				String sql2 = "select * from book_sort where ID =" + sortid;
				PreparedStatement pstmt2 = connection.prepareStatement(sql2);
				ResultSet rs2 = pstmt2.executeQuery();
				String sort = "";
				while (rs2.next()) {
					sort = rs2.getString("name");
				}
				jsonData.put("sort_id", sort);

				// 将单条记录添加到JSON数组中
				jsonArray.add(jsonData);
			}
			// 统计总记录数
			countSql = "select count(*) as count from books ";
			countSql += where;
			countPstmt = connection.prepareStatement(countSql);
			countSet = countPstmt.executeQuery();
			if (countSet.next()) {
				count = countSet.getInt("count");
			}
			if (!jsonArray.isEmpty()) {
				code = 0; // 查询成功
				msg = "查询成功";
			}
		} catch (ClassNotFoundException e) {
			msg = "class没找到"; // 类未找到异常处理
		} catch (SQLException e) {
			msg = "sql错误"; // SQL异常处理
		} finally {
			// 关闭资源
			try {
				Base.closeResource(null, pstmt, resultSet);
				Base.closeResource(connection, countPstmt, countSet);
			} catch (SQLException e) {
				msg = "关闭资源失败"; // 关闭资源异常处理
			}
		}
		// 构建返回的JSON对象
		jsonResult.put("code", code);
		jsonResult.put("count", count);
		jsonResult.put("msg", msg);
		jsonResult.put("data", jsonArray.toArray());
		// 输出JSON响应
		PrintWriter out = resp.getWriter();
		out.print(jsonResult.toString());
	}

}