/**
 * 重新排序数据库中所有表的主键ID
 * @file reorder-primary-keys.js
 * @description 将所有表的主键ID重新排序，从1开始升序，同时更新外键引用
 */

const { sequelize } = require('./config/database-simple');
const { QueryTypes } = require('sequelize');

// 根据依赖关系确定的处理顺序（被引用的表优先）
const TABLE_ORDER = [
  'roles',
  'users', 
  'farms',
  'devices',
  'products',
  'animals',
  'alerts',
  'orders',
  'sensor_data',
  'order_items',
  'user_roles',
  'seeds'
];

// 外键映射关系
const FOREIGN_KEY_MAPPINGS = {
  'animals': [{ column: 'farm_id', referencedTable: 'farms' }],
  'alerts': [
    { column: 'device_id', referencedTable: 'devices' },
    { column: 'farm_id', referencedTable: 'farms' }
  ],
  'devices': [{ column: 'farm_id', referencedTable: 'farms' }],
  'order_items': [
    { column: 'order_id', referencedTable: 'orders' },
    { column: 'product_id', referencedTable: 'products' }
  ],
  'orders': [{ column: 'user_id', referencedTable: 'users' }],
  'sensor_data': [
    { column: 'device_id', referencedTable: 'devices' },
    { column: 'farm_id', referencedTable: 'farms' }
  ],
  'user_roles': [
    { column: 'role_id', referencedTable: 'roles' },
    { column: 'user_id', referencedTable: 'users' }
  ]
};

class IDReorderManager {
  constructor() {
    this.idMappings = new Map(); // 存储旧ID到新ID的映射
    this.transaction = null;
  }

  async reorderAllTables() {
    this.transaction = await sequelize.transaction();
    
    try {
      console.log('=== 开始重新排序所有表的主键ID ===\n');
      
      // 临时禁用外键检查
      await sequelize.query('SET FOREIGN_KEY_CHECKS = 0', { transaction: this.transaction });
      
      // 按顺序处理每个表
      for (const tableName of TABLE_ORDER) {
        await this.reorderTableIDs(tableName);
      }
      
      // 重新启用外键检查
      await sequelize.query('SET FOREIGN_KEY_CHECKS = 1', { transaction: this.transaction });
      
      // 验证数据完整性
      await this.verifyIntegrity();
      
      await this.transaction.commit();
      console.log('\n✅ 所有表的ID重新排序完成!');
      
    } catch (error) {
      await this.transaction.rollback();
      console.error('❌ ID重新排序失败:', error);
      throw error;
    }
  }

  async reorderTableIDs(tableName) {
    try {
      console.log(`\n🔄 处理表: ${tableName}`);
      
      // 检查表是否存在且有数据
      const tableExists = await this.checkTableExists(tableName);
      if (!tableExists) {
        console.log(`⚠️  表 ${tableName} 不存在，跳过`);
        return;
      }
      
      const recordCount = await this.getRecordCount(tableName);
      if (recordCount === 0) {
        console.log(`ℹ️  表 ${tableName} 无数据，跳过`);
        return;
      }
      
      console.log(`   记录数: ${recordCount}`);
      
      // 获取当前所有记录（按ID排序）
      const records = await sequelize.query(
        `SELECT * FROM ${tableName} ORDER BY id`,
        { type: QueryTypes.SELECT, transaction: this.transaction }
      );
      
      if (records.length === 0) {
        console.log(`   无记录需要处理`);
        return;
      }
      
      // 创建ID映射
      const oldToNewIdMap = new Map();
      records.forEach((record, index) => {
        const oldId = record.id;
        const newId = index + 1;
        oldToNewIdMap.set(oldId, newId);
      });
      
      // 存储映射供其他表使用
      this.idMappings.set(tableName, oldToNewIdMap);
      
      // 检查是否需要重新排序
      const needsReorder = records.some((record, index) => record.id !== index + 1);
      
      if (!needsReorder) {
        console.log(`   ✅ ID已经是连续的，无需重新排序`);
        return;
      }
      
      console.log(`   🔧 重新排序ID: ${records[0].id}-${records[records.length-1].id} -> 1-${records.length}`);
      
      // 更新外键引用（如果有的话）
      await this.updateForeignKeyReferences(tableName, records);
      
      // 创建临时表
      const tempTableName = `${tableName}_temp_reorder`;
      await this.createTempTable(tableName, tempTableName);
      
      // 将数据插入临时表（使用新ID）
      await this.insertDataWithNewIDs(tableName, tempTableName, records, oldToNewIdMap);
      
      // 删除原表数据
      await sequelize.query(
        `DELETE FROM ${tableName}`,
        { transaction: this.transaction }
      );
      
      // 重置自增ID
      await sequelize.query(
        `ALTER TABLE ${tableName} AUTO_INCREMENT = 1`,
        { transaction: this.transaction }
      );
      
      // 将临时表数据复制回原表
      await this.copyDataFromTempTable(tableName, tempTableName);
      
      // 删除临时表
      await sequelize.query(
        `DROP TABLE ${tempTableName}`,
        { transaction: this.transaction }
      );
      
      console.log(`   ✅ 表 ${tableName} ID重新排序完成`);
      
    } catch (error) {
      console.error(`❌ 处理表 ${tableName} 失败:`, error.message);
      throw error;
    }
  }

  async checkTableExists(tableName) {
    const result = await sequelize.query(
      `SELECT COUNT(*) as count FROM information_schema.tables 
       WHERE table_schema = DATABASE() AND table_name = '${tableName}'`,
      { type: QueryTypes.SELECT, transaction: this.transaction }
    );
    return result[0].count > 0;
  }

  async getRecordCount(tableName) {
    const result = await sequelize.query(
      `SELECT COUNT(*) as count FROM ${tableName}`,
      { type: QueryTypes.SELECT, transaction: this.transaction }
    );
    return parseInt(result[0].count);
  }

  async updateForeignKeyReferences(tableName, records) {
    const foreignKeys = FOREIGN_KEY_MAPPINGS[tableName];
    if (!foreignKeys) return;
    
    console.log(`   🔗 更新外键引用...`);
    
    for (const fk of foreignKeys) {
      const referencedTableMapping = this.idMappings.get(fk.referencedTable);
      if (!referencedTableMapping) {
        console.log(`   ⚠️  引用表 ${fk.referencedTable} 的映射不存在，跳过外键 ${fk.column}`);
        continue;
      }
      
      // 更新外键值
      for (const record of records) {
        const oldForeignKeyValue = record[fk.column];
        if (oldForeignKeyValue && referencedTableMapping.has(oldForeignKeyValue)) {
          const newForeignKeyValue = referencedTableMapping.get(oldForeignKeyValue);
          record[fk.column] = newForeignKeyValue;
        }
      }
    }
  }

  async createTempTable(originalTable, tempTable) {
    // 先删除临时表（如果存在）
    try {
      await sequelize.query(
        `DROP TABLE IF EXISTS ${tempTable}`,
        { transaction: this.transaction }
      );
    } catch (error) {
      // 忽略删除错误
    }
    
    await sequelize.query(
      `CREATE TABLE ${tempTable} LIKE ${originalTable}`,
      { transaction: this.transaction }
    );
  }

  async insertDataWithNewIDs(originalTable, tempTable, records, idMapping) {
    if (records.length === 0) return;
    
    // 获取表结构
    const columns = await sequelize.query(
      `SELECT COLUMN_NAME FROM information_schema.columns 
       WHERE table_schema = DATABASE() AND table_name = '${originalTable}' 
       ORDER BY ordinal_position`,
      { type: QueryTypes.SELECT, transaction: this.transaction }
    );
    
    const columnNames = columns.map(col => col.COLUMN_NAME);
    
    // 批量插入数据
    for (let i = 0; i < records.length; i += 100) {
      const batch = records.slice(i, i + 100);
      const values = batch.map((record, batchIndex) => {
        const newId = i + batchIndex + 1;
        const values = columnNames.map(col => {
          if (col === 'id') {
            return newId;
          }
          const value = record[col];
          if (value === null || value === undefined) {
            return 'NULL';
          }
          if (typeof value === 'string') {
            return `'${value.replace(/'/g, "''")}'`;
          }
          if (value instanceof Date) {
            return `'${value.toISOString().slice(0, 19).replace('T', ' ')}'`;
          }
          if (typeof value === 'object') {
            return `'${JSON.stringify(value).replace(/'/g, "''")}'`;
          }
          return value;
        });
        return `(${values.join(', ')})`;
      });
      
      await sequelize.query(
        `INSERT INTO ${tempTable} (${columnNames.join(', ')}) VALUES ${values.join(', ')}`,
        { transaction: this.transaction }
      );
    }
  }

  async copyDataFromTempTable(originalTable, tempTable) {
    await sequelize.query(
      `INSERT INTO ${originalTable} SELECT * FROM ${tempTable}`,
      { transaction: this.transaction }
    );
  }

  async verifyIntegrity() {
    console.log('\n🔍 验证数据完整性...');
    
    for (const [tableName, foreignKeys] of Object.entries(FOREIGN_KEY_MAPPINGS)) {
      if (!foreignKeys) continue;
      
      for (const fk of foreignKeys) {
        try {
          const result = await sequelize.query(`
            SELECT COUNT(*) as invalid_count
            FROM ${tableName} t
            WHERE t.${fk.column} IS NOT NULL 
              AND t.${fk.column} NOT IN (
                SELECT id FROM ${fk.referencedTable} WHERE id IS NOT NULL
              )
          `, { type: QueryTypes.SELECT, transaction: this.transaction });
          
          const invalidCount = parseInt(result[0].invalid_count);
          if (invalidCount > 0) {
            throw new Error(`表 ${tableName}.${fk.column} 有 ${invalidCount} 个无效的外键引用`);
          }
        } catch (error) {
          console.error(`❌ 完整性检查失败: ${tableName}.${fk.column}`, error.message);
          throw error;
        }
      }
    }
    
    console.log('✅ 数据完整性验证通过');
  }
}

async function reorderPrimaryKeys() {
  const manager = new IDReorderManager();
  await manager.reorderAllTables();
}

// 如果直接运行此脚本
if (require.main === module) {
  reorderPrimaryKeys()
    .then(() => {
      console.log('\n🎉 主键ID重新排序完成!');
      process.exit(0);
    })
    .catch(error => {
      console.error('💥 主键ID重新排序失败:', error);
      process.exit(1);
    })
    .finally(() => {
      sequelize.close();
    });
}

module.exports = { reorderPrimaryKeys, IDReorderManager };