/**
 * 图片数据迁移脚本 - Node.js
 * Feature: database-migration, Property 2: 数据记录数一致性
 * Validates: Requirements 9.3
 * 
 * 源表: MySQL picture (1,175 条记录)
 * 目标表: SQL Server pictures
 * 
 * 字段映射:
 * - id -> id
 * - imgurl -> img_url
 * - token -> token
 * - addtime (Unix时间戳) -> created_at (DATETIME2)
 * - status -> status
 * - type -> type
 */

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, "''") + "'";
}

// Unix时间戳转换为SQL Server DATETIME2格式
function unixToDatetime(timestamp) {
    if (!timestamp || timestamp === 0) {
        return 'GETDATE()';
    }
    const date = new Date(timestamp * 1000);
    const year = date.getFullYear();
    const month = String(date.getMonth() + 1).padStart(2, '0');
    const day = String(date.getDate()).padStart(2, '0');
    const hours = String(date.getHours()).padStart(2, '0');
    const minutes = String(date.getMinutes()).padStart(2, '0');
    const seconds = String(date.getSeconds()).padStart(2, '0');
    return `'${year}-${month}-${day} ${hours}:${minutes}:${seconds}'`;
}

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

// 批量插入图片数据
async function insertPicturesBatch(pool, pictures, batchSize = 100) {
    if (pictures.length === 0) return 0;
    
    let insertedCount = 0;
    
    // 分批处理
    for (let i = 0; i < pictures.length; i += batchSize) {
        const batch = pictures.slice(i, i + batchSize);
        let sqlBatch = 'SET IDENTITY_INSERT pictures ON;\n';
        
        for (const pic of batch) {
            const typeValue = pic.type !== null && pic.type !== undefined ? pic.type : 'NULL';
            sqlBatch += `
INSERT INTO pictures (id, img_url, token, created_at, status, type)
VALUES (${pic.id}, ${escapeString(pic.imgurl)}, ${escapeString(pic.token)}, ${unixToDatetime(pic.addtime)}, ${pic.status}, ${typeValue});
`;
        }
        
        sqlBatch += 'SET IDENTITY_INSERT pictures OFF;';
        
        try {
            await pool.request().batch(sqlBatch);
            insertedCount += batch.length;
            console.log(`  批次 ${Math.floor(i / batchSize) + 1}: 成功插入 ${batch.length} 条记录`);
        } catch (err) {
            console.error(`  批次 ${Math.floor(i / batchSize) + 1} 批量插入失败:`, err.message);
            // 如果批量失败，尝试逐条插入
            for (const pic of batch) {
                try {
                    const typeValue = pic.type !== null && pic.type !== undefined ? pic.type : 'NULL';
                    const singleSql = `
SET IDENTITY_INSERT pictures ON;
INSERT INTO pictures (id, img_url, token, created_at, status, type)
VALUES (${pic.id}, ${escapeString(pic.imgurl)}, ${escapeString(pic.token)}, ${unixToDatetime(pic.addtime)}, ${pic.status}, ${typeValue});
SET IDENTITY_INSERT pictures OFF;`;
                    
                    await pool.request().batch(singleSql);
                    insertedCount++;
                } catch (singleErr) {
                    console.error(`    ✗ 插入图片 ${pic.id} 失败:`, singleErr.message);
                }
            }
        }
    }
    
    return insertedCount;
}

async function main() {
    console.log('========================================');
    console.log('图片数据迁移脚本 - 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('正在获取已迁移的图片ID...');
        const migratedIds = await getMigratedIds(sqlPool);
        console.log(`已迁移图片数: ${migratedIds.size}\n`);
        
        // 从 MySQL 获取所有图片数据
        console.log('正在从 MySQL 读取图片数据...');
        const [rows] = await mysqlConn.execute(`
            SELECT id, imgurl, token, addtime, status, type
            FROM picture
            ORDER BY id
        `);
        console.log(`MySQL 图片总数: ${rows.length}\n`);
        
        // 过滤出未迁移的图片
        const picturesToMigrate = rows.filter(pic => !migratedIds.has(pic.id));
        console.log(`待迁移图片数: ${picturesToMigrate.length}\n`);
        
        if (picturesToMigrate.length === 0) {
            console.log('所有图片数据已迁移完成！');
        } else {
            // 批量迁移
            console.log('开始迁移图片数据...');
            const inserted = await insertPicturesBatch(sqlPool, picturesToMigrate);
            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 picture');
        const sqlResult = await sqlPool.request().query('SELECT COUNT(*) as count FROM pictures');
        
        console.log(`MySQL picture 表记录数: ${mysqlCount[0].count}`);
        console.log(`SQL Server pictures 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}`);
        }
        
        // 显示迁移统计
        console.log('\n迁移统计:');
        const stats = await sqlPool.request().query(`
            SELECT 
                COUNT(*) as total,
                COUNT(CASE WHEN type IS NULL THEN 1 END) as null_type,
                COUNT(CASE WHEN type IS NOT NULL THEN 1 END) as with_type
            FROM pictures
        `);
        console.log(`  总记录数: ${stats.recordset[0].total}`);
        console.log(`  有类型: ${stats.recordset[0].with_type}`);
        console.log(`  无类型: ${stats.recordset[0].null_type}`);
        
    } 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();