// =====================================================
// 修復的資料庫雙寫同步機制
// 確保主機和備機使用各自的 ID 序列
// =====================================================

import mysql from 'mysql2/promise';
import { DatabaseFailover } from './database-failover';

export interface WriteResult {
  success: boolean;
  masterSuccess: boolean;
  slaveSuccess: boolean;
  masterError?: string;
  slaveError?: string;
  masterId?: string;
  slaveId?: string;
}

export class DatabaseSyncFixed {
  private masterPool: mysql.Pool | null = null;
  private slavePool: mysql.Pool | null = null;
  private dbFailover: DatabaseFailover;

  constructor() {
    this.dbFailover = new DatabaseFailover();
    this.initializePools();
  }

  // 初始化連接池
  private initializePools(): void {
    try {
      // 主機連接池
      this.masterPool = mysql.createPool({
        host: process.env.DB_HOST || 'mysql.theaken.com',
        port: parseInt(process.env.DB_PORT || '33306'),
        user: process.env.DB_USER || 'AI_Platform',
        password: process.env.DB_PASSWORD || 'Aa123456',
        database: process.env.DB_NAME || 'db_AI_Platform',
        charset: 'utf8mb4',
        connectionLimit: 10,
        acquireTimeout: 60000,
        timeout: 60000,
        reconnect: true
      });

      // 備機連接池
      this.slavePool = mysql.createPool({
        host: process.env.SLAVE_DB_HOST || '122.100.99.161',
        port: parseInt(process.env.SLAVE_DB_PORT || '43306'),
        user: process.env.SLAVE_DB_USER || 'A999',
        password: process.env.SLAVE_DB_PASSWORD || '1023',
        database: process.env.SLAVE_DB_NAME || 'db_AI_Platform',
        charset: 'utf8mb4',
        connectionLimit: 10,
        acquireTimeout: 60000,
        timeout: 60000,
        reconnect: true
      });

      console.log('✅ 修復的雙寫連接池初始化成功');
    } catch (error) {
      console.error('❌ 修復的雙寫連接池初始化失敗:', error);
    }
  }

  // 智能雙寫插入 - 每個資料庫使用自己的 ID
  async smartDualInsert(tableName: string, data: Record<string, any>): Promise<WriteResult> {
    const result: WriteResult = {
      success: false,
      masterSuccess: false,
      slaveSuccess: false
    };

    try {
      // 同時寫入主機和備機，各自生成 ID
      const masterPromise = this.insertToMaster(tableName, data);
      const slavePromise = this.insertToSlave(tableName, data);

      const [masterResult, slaveResult] = await Promise.allSettled([masterPromise, slavePromise]);

      result.masterSuccess = masterResult.status === 'fulfilled';
      result.slaveSuccess = slaveResult.status === 'fulfilled';
      result.success = result.masterSuccess || result.slaveSuccess;

      if (masterResult.status === 'fulfilled') {
        result.masterId = masterResult.value;
      } else {
        result.masterError = masterResult.reason instanceof Error ? masterResult.reason.message : '主機寫入失敗';
      }

      if (slaveResult.status === 'fulfilled') {
        result.slaveId = slaveResult.value;
      } else {
        result.slaveError = slaveResult.reason instanceof Error ? slaveResult.reason.message : '備機寫入失敗';
      }

      console.log(`📝 智能雙寫結果: 主機${result.masterSuccess ? '✅' : '❌'} 備機${result.slaveSuccess ? '✅' : '❌'}`);
      
    } catch (error) {
      result.masterError = error instanceof Error ? error.message : '智能雙寫執行失敗';
    }

    return result;
  }

  // 寫入主機 - 使用主機的 ID 生成
  private async insertToMaster(tableName: string, data: Record<string, any>): Promise<string> {
    if (!this.masterPool) {
      throw new Error('主機連接池不可用');
    }

    const connection = await this.masterPool.getConnection();
    try {
      // 生成主機的 UUID
      const [uuidResult] = await connection.execute('SELECT UUID() as id');
      const masterId = (uuidResult as any)[0].id;

      // 構建插入 SQL
      const columns = Object.keys(data).join(', ');
      const placeholders = Object.keys(data).map(() => '?').join(', ');
      const values = Object.values(data);

      const sql = `INSERT INTO ${tableName} (id, ${columns}) VALUES (?, ${placeholders})`;
      await connection.execute(sql, [masterId, ...values]);

      console.log(`✅ 主機寫入成功: ${masterId}`);
      return masterId;
    } finally {
      connection.release();
    }
  }

  // 寫入備機 - 使用備機的 ID 生成
  private async insertToSlave(tableName: string, data: Record<string, any>): Promise<string> {
    if (!this.slavePool) {
      throw new Error('備機連接池不可用');
    }

    const connection = await this.slavePool.getConnection();
    try {
      // 生成備機的 UUID
      const [uuidResult] = await connection.execute('SELECT UUID() as id');
      const slaveId = (uuidResult as any)[0].id;

      // 構建插入 SQL
      const columns = Object.keys(data).join(', ');
      const placeholders = Object.keys(data).map(() => '?').join(', ');
      const values = Object.values(data);

      const sql = `INSERT INTO ${tableName} (id, ${columns}) VALUES (?, ${placeholders})`;
      await connection.execute(sql, [slaveId, ...values]);

      console.log(`✅ 備機寫入成功: ${slaveId}`);
      return slaveId;
    } finally {
      connection.release();
    }
  }

  // 智能雙寫關聯表 - 使用對應的競賽 ID
  async smartDualInsertRelation(
    relationTable: string, 
    competitionId: string, 
    relationData: any[], 
    relationIdField: string
  ): Promise<WriteResult> {
    const result: WriteResult = {
      success: false,
      masterSuccess: false,
      slaveSuccess: false
    };

    try {
      // 先獲取主機和備機的競賽 ID 對應關係
      const masterCompetitionId = await this.getMasterCompetitionId(competitionId);
      const slaveCompetitionId = await this.getSlaveCompetitionId(competitionId);

      if (!masterCompetitionId || !slaveCompetitionId) {
        throw new Error('找不到對應的競賽 ID');
      }

      // 同時寫入關聯數據
      const masterPromise = this.insertRelationsToMaster(relationTable, masterCompetitionId, relationData, relationIdField);
      const slavePromise = this.insertRelationsToSlave(relationTable, slaveCompetitionId, relationData, relationIdField);

      const [masterResult, slaveResult] = await Promise.allSettled([masterPromise, slavePromise]);

      result.masterSuccess = masterResult.status === 'fulfilled';
      result.slaveSuccess = slaveResult.status === 'fulfilled';
      result.success = result.masterSuccess || result.slaveSuccess;

      if (masterResult.status === 'rejected') {
        result.masterError = masterResult.reason instanceof Error ? masterResult.reason.message : '主機關聯寫入失敗';
      }
      if (slaveResult.status === 'rejected') {
        result.slaveError = slaveResult.reason instanceof Error ? slaveResult.reason.message : '備機關聯寫入失敗';
      }

      console.log(`📝 關聯雙寫結果: 主機${result.masterSuccess ? '✅' : '❌'} 備機${result.slaveSuccess ? '✅' : '❌'}`);
      
    } catch (error) {
      result.masterError = error instanceof Error ? error.message : '關聯雙寫執行失敗';
    }

    return result;
  }

  // 獲取主機競賽 ID
  private async getMasterCompetitionId(competitionId: string): Promise<string | null> {
    if (!this.masterPool) return null;
    
    const connection = await this.masterPool.getConnection();
    try {
      const [rows] = await connection.execute('SELECT id FROM competitions WHERE id = ?', [competitionId]);
      return (rows as any[])[0]?.id || null;
    } finally {
      connection.release();
    }
  }

  // 獲取備機競賽 ID
  private async getSlaveCompetitionId(competitionId: string): Promise<string | null> {
    if (!this.slavePool) return null;
    
    const connection = await this.slavePool.getConnection();
    try {
      const [rows] = await connection.execute('SELECT id FROM competitions WHERE id = ?', [competitionId]);
      return (rows as any[])[0]?.id || null;
    } finally {
      connection.release();
    }
  }

  // 寫入主機關聯表
  private async insertRelationsToMaster(
    relationTable: string, 
    competitionId: string, 
    relationData: any[], 
    relationIdField: string
  ): Promise<void> {
    if (!this.masterPool) return;

    const connection = await this.masterPool.getConnection();
    try {
      for (const data of relationData) {
        const [uuidResult] = await connection.execute('SELECT UUID() as id');
        const relationId = (uuidResult as any)[0].id;

        const sql = `INSERT INTO ${relationTable} (id, competition_id, ${relationIdField}) VALUES (?, ?, ?)`;
        await connection.execute(sql, [relationId, competitionId, data[relationIdField]]);
      }
    } finally {
      connection.release();
    }
  }

  // 寫入備機關聯表
  private async insertRelationsToSlave(
    relationTable: string, 
    competitionId: string, 
    relationData: any[], 
    relationIdField: string
  ): Promise<void> {
    if (!this.slavePool) return;

    const connection = await this.slavePool.getConnection();
    try {
      for (const data of relationData) {
        const [uuidResult] = await connection.execute('SELECT UUID() as id');
        const relationId = (uuidResult as any)[0].id;

        const sql = `INSERT INTO ${relationTable} (id, competition_id, ${relationIdField}) VALUES (?, ?, ?)`;
        await connection.execute(sql, [relationId, competitionId, data[relationIdField]]);
      }
    } finally {
      connection.release();
    }
  }

  // 清理資源
  async close(): Promise<void> {
    if (this.masterPool) {
      await this.masterPool.end();
    }
    if (this.slavePool) {
      await this.slavePool.end();
    }
  }
}

// 導出實例
export const dbSyncFixed = new DatabaseSyncFixed();