// 添加到文件开头
import sqlite3 from 'sqlite3';
import { promisify } from 'util';

sqlite3.verbose();

// 数据库连接池简单实现
const dbConnections = new Map();

// 打开数据库并添加到连接池
async function openDatabase(dbPath) {
  console.log(`打开数据库连接: ${dbPath}`);

  // 检查是否已有连接
  if (dbConnections.has(dbPath)) {
    console.log(`使用现有数据库连接: ${dbPath}`);
    return dbConnections.get(dbPath);
  }

  return new Promise((resolve, reject) => {
    const db = new sqlite3.Database(dbPath, (err) => {
      if (err) {
        console.error(`打开数据库失败: ${err.message}`);
        reject(err);
        return;
      }

      console.log(`成功打开数据库: ${dbPath}`);

      //  promisify数据库方法
      db.getAsync = promisify(db.get).bind(db);
      db.allAsync = promisify(db.all).bind(db);

      // 自定义实现runAsync以获取lastID
      db.runAsync = function(sql, params) {
        return new Promise((resolve, reject) => {
          this.run(sql, params, function(err) {
            if (err) {
              reject(err);
            } else {
              resolve({
                lastID: this.lastID,
                changes: this.changes
              });
            }
          });
        });
      };

      db.execAsync = promisify(db.exec).bind(db);

      // 添加到连接池
      dbConnections.set(dbPath, db);

      resolve(db);
    });
  });
}

// 添加重试机制的执行函数
async function executeWithRetry(db, operation, maxRetries = 3) {
  let retries = 0;
  while (retries < maxRetries) {
    try {
      return await operation();
    } catch (error) {
      if (error.code === 'SQLITE_BUSY' && retries < maxRetries - 1) {
        retries++;
        console.log(`数据库忙，正在重试 (${retries}/${maxRetries})...`);
        await new Promise(resolve => setTimeout(resolve, 500 * retries)); // 指数退避
      } else {
        throw error;
      }
    }
  }
}

// 修改batchInsert函数使用重试机制
async function batchInsert(db, table, data) {
  if (!data || data.length === 0) {
    return;
  }

  const columns = Object.keys(data[0]).join(', ');
  const placeholders = data.map(() => {
    return '(' + Object.keys(data[0]).map(() => '?').join(', ') + ')';
  }).join(', ');

  const values = [];
  data.forEach(item => {
    Object.values(item).forEach(value => {
      values.push(value);
    });
  });

  const sql = `INSERT INTO ${table} (${columns}) VALUES ${placeholders}`;

  return executeWithRetry(db, async () => {
    await db.runAsync(sql, values);
    console.log(`成功插入 ${data.length} 条记录到 ${table} 表`);
  });
}

// 导出修改后的函数
export {
  openDatabase,
  batchInsert,
  executeWithRetry
};