/**
 * 快递公司数据迁移脚本 - Node.js
 * Feature: database-migration, Property 2: 数据记录数一致性
 * Validates: Requirements 9.2
 * 
 * 源表: MySQL delivery (11 条记录)
 * 目标表: SQL Server deliveries
 * 
 * 字段映射:
 * - id -> id (SMALLINT)
 * - name -> name (NVARCHAR(50))
 * - code -> code (NVARCHAR(30))
 */

const mysql = require('mysql2/promise');
const sql = require('mssql');

// MySQL 配置
const mysqlConfig = {
    host: '192.168.195.16',
    port: 1887,
    user: 'root',
    password: 'Dbt@com@123',
    database: 'youdas',
    charset: 'utf8mb4'
};

// SQL Server 配置
const sqlServerConfig = {
    server: '192.168.195.15',
    port: 1433,
    user: 'sa',
    password: 'Dbt@com@123',
    database: 'honey_box',
    options: {
        encrypt: false,
        trustServerCertificate: true
    }
};

// 转义SQL字符串
function escapeString(str) {
    if (str === null || str === undefined) return 'NULL';
    return "N'" + String(str).replace(/'/g, "''") + "'";
}

// 获取已迁移的快递公司ID列表
async function getMigratedIds(pool) {
    const result = await pool.request().query('SELECT id FROM deliveries');
    return new Set(result.recordset.map(r => r.id));
}

// 批量插入快递公司数据
async function insertDeliveriesBatch(pool, deliveries) {
    if (deliveries.length === 0) return 0;
    
    let insertedCount = 0;
    
    // 构建批量插入SQL
    let sqlBatch = 'SET IDENTITY_INSERT deliveries ON;\n';
    
    for (const delivery of deliveries) {
        sqlBatch += `
INSERT INTO deliveries (id, name, code)
VALUES (${delivery.id}, ${escapeString(delivery.name)}, ${escapeString(delivery.code)});
`;
    }
    
    sqlBatch += 'SET IDENTITY_INSERT deliveries OFF;';
    
    try {
        await pool.request().batch(sqlBatch);
        insertedCount = deliveries.length;
        console.log(`批量插入成功: ${insertedCount} 条记录`);
    } catch (err) {
        console.error('批量插入失败:', err.message);
        // 如果批量失败，尝试逐条插入
        for (const delivery of deliveries) {
            try {
                const singleSql = `
SET IDENTITY_INSERT deliveries ON;
INSERT INTO deliveries (id, name, code)
VALUES (${delivery.id}, ${escapeString(delivery.name)}, ${escapeString(delivery.code)});
SET IDENTITY_INSERT deliveries OFF;`;
                
                await pool.request().batch(singleSql);
                insertedCount++;
                console.log(`  ✓ 插入快递公司 ${delivery.id}: ${delivery.name} (${delivery.code})`);
            } catch (singleErr) {
                console.error(`  ✗ 插入快递公司 ${delivery.id} (${delivery.name}) 失败:`, singleErr.message);
            }
        }
    }
    
    return insertedCount;
}

async function main() {
    console.log('========================================');
    console.log('快递公司数据迁移脚本 - Node.js');
    console.log('========================================\n');
    
    let mysqlConn = null;
    let sqlPool = null;
    
    try {
        // 连接 MySQL
        console.log('正在连接 MySQL...');
        mysqlConn = await mysql.createConnection(mysqlConfig);
        console.log('MySQL 连接成功\n');
        
        // 连接 SQL Server
        console.log('正在连接 SQL Server...');
        sqlPool = await sql.connect(sqlServerConfig);
        console.log('SQL Server 连接成功\n');
        
        // 获取已迁移的ID
        console.log('正在获取已迁移的快递公司ID...');
        const migratedIds = await getMigratedIds(sqlPool);
        console.log(`已迁移快递公司数: ${migratedIds.size}\n`);
        
        // 从 MySQL 获取所有快递公司数据
        console.log('正在从 MySQL 读取快递公司数据...');
        const [rows] = await mysqlConn.execute(`
            SELECT id, name, code
            FROM delivery
            ORDER BY id
        `);
        console.log(`MySQL 快递公司总数: ${rows.length}\n`);
        
        // 显示快递公司列表
        console.log('快递公司列表:');
        for (const row of rows) {
            const status = migratedIds.has(row.id) ? '已迁移' : '待迁移';
            console.log(`  ${row.id}. ${row.name} (${row.code}) [${status}]`);
        }
        console.log('');
        
        // 过滤出未迁移的快递公司
        const deliveriesToMigrate = rows.filter(delivery => !migratedIds.has(delivery.id));
        console.log(`待迁移快递公司数: ${deliveriesToMigrate.length}\n`);
        
        if (deliveriesToMigrate.length === 0) {
            console.log('所有快递公司数据已迁移完成！');
        } else {
            // 批量迁移
            console.log('开始迁移快递公司数据...');
            const inserted = await insertDeliveriesBatch(sqlPool, deliveriesToMigrate);
            console.log(`\n迁移完成！共插入 ${inserted} 条记录`);
        }
        
        // 验证迁移结果
        console.log('\n========================================');
        console.log('迁移结果验证');
        console.log('========================================');
        
        const [mysqlCount] = await mysqlConn.execute('SELECT COUNT(*) as count FROM delivery');
        const sqlResult = await sqlPool.request().query('SELECT COUNT(*) as count FROM deliveries');
        
        console.log(`MySQL delivery 表记录数: ${mysqlCount[0].count}`);
        console.log(`SQL Server deliveries 表记录数: ${sqlResult.recordset[0].count}`);
        
        if (mysqlCount[0].count === sqlResult.recordset[0].count) {
            console.log('\n✅ 数据迁移完成，记录数一致！');
        } else {
            console.log(`\n⚠️ 记录数不一致，差异: ${mysqlCount[0].count - sqlResult.recordset[0].count}`);
        }
        
        // 显示迁移后的快递公司列表
        console.log('\n迁移后的快递公司列表:');
        const migratedDeliveries = await sqlPool.request().query('SELECT id, name, code FROM deliveries ORDER BY id');
        for (const delivery of migratedDeliveries.recordset) {
            console.log(`  ${delivery.id}. ${delivery.name} (${delivery.code})`);
        }
        
    } catch (err) {
        console.error('迁移过程中发生错误:', err);
        process.exit(1);
    } finally {
        // 关闭连接
        if (mysqlConn) await mysqlConn.end();
        if (sqlPool) await sqlPool.close();
    }
}

main();