/**
 * 修复数据库锁定问题 - 简化版
 * 分步骤执行，避免复杂查询导致临时表满
 */

require('dotenv').config();
const mysql = require('mysql2/promise');

async function fixDatabaseLocks() {
    let connection;

    try {
        connection = await mysql.createConnection({
            host: process.env.DB_HOST,
            port: process.env.DB_PORT || 3306,
            user: process.env.DB_USER,
            password: process.env.DB_PASSWORD,
            database: process.env.DB_DATABASE
        });

        console.log('✅ 已连接到数据库');

        // 步骤1: 查找并终止所有waiting for handler commit的进程
        console.log('\n📋 步骤1: 查找锁定的进程...');
        const [processes] = await connection.query(
            "SELECT Id, State, Info FROM INFORMATION_SCHEMA.PROCESSLIST WHERE State LIKE '%waiting for handler commit%'"
        );

        console.log(`找到 ${processes.length} 个锁定的进程`);

        let killedCount = 0;
        for (const p of processes) {
            try {
                console.log(`  正在终止进程 ${p.Id}...`);
                await connection.query(`KILL ${p.Id}`);
                console.log(`  ✅ 已终止进程 ${p.Id}`);
                killedCount++;
            } catch (err) {
                console.log(`  ⚠️ 无法终止进程 ${p.Id}:`, err.message);
            }
        }

        console.log(`\n✅ 成功终止 ${killedCount} 个锁定的进程`);

        // 步骤2: 终止所有Sleep状态的连接
        console.log('\n📋 步骤2: 终止Sleep状态的连接...');
        const [allProcesses] = await connection.query('SHOW FULL PROCESSLIST');

        let sleepKilled = 0;
        for (const p of allProcesses) {
            if (p.Command === 'Sleep' && p.Id !== connection.threadId) {
                try {
                    await connection.query(`KILL ${p.Id}`);
                    console.log(`  ✅ 已终止Sleep进程 ${p.Id}`);
                    sleepKilled++;
                } catch (err) {
                    console.log(`  ⚠️ 无法终止进程 ${p.Id}:`, err.message);
                }
            }
        }

        console.log(`\n✅ 成功终止 ${sleepKilled} 个Sleep连接`);

        // 步骤3: 检查是否有重复的确认记录（使用简单查询）
        console.log('\n📋 步骤3: 检查重复记录...');
        const [allConfirmations] = await connection.query(
            'SELECT id, user_id, training_unit_id FROM training_confirmations ORDER BY user_id, training_unit_id, id'
        );

        console.log(`总共有 ${allConfirmations.length} 条确认记录`);

        // 找出重复的记录（在应用层处理，避免复杂SQL）
        const seen = new Map();
        const duplicates = [];

        for (const record of allConfirmations) {
            const key = `${record.user_id}_${record.training_unit_id}`;
            if (seen.has(key)) {
                // 这是重复的，标记为要删除
                duplicates.push(record.id);
            } else {
                // 第一次见到，保留
                seen.set(key, record.id);
            }
        }

        if (duplicates.length > 0) {
            console.log(`\n发现 ${duplicates.length} 条重复记录，正在删除...`);
            for (const id of duplicates) {
                await connection.query('DELETE FROM training_confirmations WHERE id = ?', [id]);
                console.log(`  ✅ 已删除重复记录 ID: ${id}`);
            }
        } else {
            console.log('✅ 没有发现重复记录');
        }

        // 步骤4: 解锁所有表
        console.log('\n📋 步骤4: 解锁所有表...');
        await connection.query('UNLOCK TABLES');
        console.log('✅ 表已解锁');

        console.log('\n✅ 所有操作完成！');
        console.log('\n💡 现在可以重新测试预招录确认功能了');
        console.log('\n建议：如果问题仍然存在，可能需要重启Node.js服务器以释放连接池');

    } catch (error) {
        console.error('❌ 操作失败:', error.message);
        console.error('错误详情:', error);
        process.exit(1);
    } finally {
        if (connection) {
            await connection.end();
        }
    }
}

fixDatabaseLocks();