import { Knex } from 'knex';
import { db } from '../database';

export class DatabaseOptimizationService {
  /**
   * 分析慢查询日志
   * @param params 分析参数
   * @param traceInfo 追踪信息
   * @returns 慢查询分析结果
   */
  public static async analyzeSlowQueries(
    params: {
      timeRange: { start: string; end: string };
      minExecutionTime?: number;
      limit?: number;
    },
    traceInfo: {
      tenantId: string;
      shopId: string;
      taskId: string;
      traceId: string;
      businessType: 'TOC' | 'TOB';
    }
  ): Promise<{
    timestamp: string;
    timeRange: { start: string; end: string };
    totalSlowQueries: number;
    topSlowQueries: Array<{
      query: string;
      executionTime: number;
      callCount: number;
      averageExecutionTime: number;
      peakExecutionTime: number;
    }>;
    recommendations: string[];
  }> {
    try {
      const timestamp = new Date().toISOString();
      
      // 模拟慢查询分析数据
      const topSlowQueries = Array.from({ length: 10 }, (_, index) => ({
        query: `SELECT * FROM cf_orders WHERE customer_id = ? AND order_date BETWEEN ? AND ?`,
        executionTime: Math.random() * 5000 + 1000,
        callCount: Math.floor(Math.random() * 1000) + 100,
        averageExecutionTime: Math.random() * 3000 + 500,
        peakExecutionTime: Math.random() * 8000 + 2000,
      }));
      
      const totalSlowQueries = topSlowQueries.reduce((sum, query) => sum + query.callCount, 0);
      
      // 生成优化建议
      const recommendations = [
        '为customer_id和order_date字段添加复合索引',
        '优化查询语句，减少SELECT *的使用',
        '考虑使用分页查询，避免一次性获取大量数据',
        '检查数据库连接池配置，确保连接数合理',
        '定期分析慢查询日志，及时发现和解决性能问题',
      ];
      
      return {
        timestamp,
        timeRange: params.timeRange,
        totalSlowQueries,
        topSlowQueries,
        recommendations,
      };
    } catch (error) {
      console.error('Error analyzing slow queries:', error);
      throw new Error('Failed to analyze slow queries');
    }
  }

  /**
   * 优化数据库索引
   * @param params 索引优化参数
   * @param traceInfo 追踪信息
   * @returns 索引优化结果
   */
  public static async optimizeIndexes(
    params: {
      tableName: string;
      columns: string[];
      indexType?: 'BTREE' | 'HASH';
    },
    traceInfo: {
      tenantId: string;
      shopId: string;
      taskId: string;
      traceId: string;
      businessType: 'TOC' | 'TOB';
    }
  ): Promise<{
    timestamp: string;
    tableName: string;
    columns: string[];
    indexName: string;
    indexType: string;
    status: string;
    executionTime: number;
  }> {
    try {
      const timestamp = new Date().toISOString();
      const indexName = `idx_${params.tableName}_${params.columns.join('_')}`;
      const indexType = params.indexType || 'BTREE';
      
      // 模拟索引创建
      const executionTime = Math.random() * 5000 + 1000;
      
      return {
        timestamp,
        tableName: params.tableName,
        columns: params.columns,
        indexName,
        indexType,
        status: 'success',
        executionTime,
      };
    } catch (error) {
      console.error('Error optimizing indexes:', error);
      throw new Error('Failed to optimize indexes');
    }
  }

  /**
   * 分析表结构
   * @param params 分析参数
   * @param traceInfo 追踪信息
   * @returns 表结构分析结果
   */
  public static async analyzeTableStructure(
    params: {
      tableName: string;
    },
    traceInfo: {
      tenantId: string;
      shopId: string;
      taskId: string;
      traceId: string;
      businessType: 'TOC' | 'TOB';
    }
  ): Promise<{
    timestamp: string;
    tableName: string;
    columns: Array<{
      name: string;
      type: string;
      nullable: boolean;
      default: any;
      key: string;
    }>;
    indexes: Array<{
      name: string;
      columns: string[];
      type: string;
    }>;
    recommendations: string[];
  }> {
    try {
      const timestamp = new Date().toISOString();
      
      // 模拟表结构分析数据
      const columns = [
        { name: 'id', type: 'INT', nullable: false, default: null, key: 'PRIMARY' },
        { name: 'customer_id', type: 'INT', nullable: false, default: null, key: '' },
        { name: 'order_date', type: 'DATETIME', nullable: false, default: null, key: '' },
        { name: 'total_amount', type: 'DECIMAL(10,2)', nullable: false, default: 0, key: '' },
        { name: 'status', type: 'VARCHAR(20)', nullable: false, default: 'pending', key: '' },
        { name: 'created_at', type: 'TIMESTAMP', nullable: false, default: 'CURRENT_TIMESTAMP', key: '' },
        { name: 'updated_at', type: 'TIMESTAMP', nullable: false, default: 'CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP', key: '' },
      ];
      
      const indexes = [
        { name: 'PRIMARY', columns: ['id'], type: 'BTREE' },
      ];
      
      // 生成优化建议
      const recommendations = [
        `为 ${params.tableName} 表的 customer_id 字段添加索引`,
        `为 ${params.tableName} 表的 order_date 字段添加索引`,
        `考虑为 ${params.tableName} 表的 status 字段添加索引，以提高查询性能`,
      ];
      
      return {
        timestamp,
        tableName: params.tableName,
        columns,
        indexes,
        recommendations,
      };
    } catch (error) {
      console.error('Error analyzing table structure:', error);
      throw new Error('Failed to analyze table structure');
    }
  }

  /**
   * 执行数据库优化建议
   * @param params 优化参数
   * @param traceInfo 追踪信息
   * @returns 优化执行结果
   */
  public static async executeOptimization(
    params: {
      recommendations: Array<{
        type: 'index' | 'query' | 'structure';
        details: any;
      }>;
    },
    traceInfo: {
      tenantId: string;
      shopId: string;
      taskId: string;
      traceId: string;
      businessType: 'TOC' | 'TOB';
    }
  ): Promise<{
    timestamp: string;
    executedRecommendations: number;
    successfulExecutions: number;
    failedExecutions: number;
    results: Array<{
      recommendation: any;
      status: 'success' | 'failure';
      message: string;
    }>;
  }> {
    try {
      const timestamp = new Date().toISOString();
      const results = [];
      let successfulExecutions = 0;
      let failedExecutions = 0;
      
      for (const recommendation of params.recommendations) {
        try {
          // 模拟执行优化建议
          const success = Math.random() > 0.1; // 90% success rate
          
          if (success) {
            successfulExecutions++;
            results.push({
              recommendation,
              status: 'success' as 'success',
              message: 'Optimization executed successfully',
            });
          } else {
            failedExecutions++;
            results.push({
              recommendation,
              status: 'failure' as 'failure',
              message: 'Failed to execute optimization',
            });
          }
        } catch (error) {
          failedExecutions++;
          results.push({
            recommendation,
            status: 'failure' as 'failure',
            message: error.message,
          });
        }
      }
      
      return {
        timestamp,
        executedRecommendations: params.recommendations.length,
        successfulExecutions,
        failedExecutions,
        results,
      };
    } catch (error) {
      console.error('Error executing optimization:', error);
      throw new Error('Failed to execute optimization');
    }
  }

  /**
   * 获取数据库性能指标
   * @param params 指标参数
   * @param traceInfo 追踪信息
   * @returns 性能指标
   */
  public static async getDatabaseMetrics(
    params: {
      metrics: string[];
    },
    traceInfo: {
      tenantId: string;
      shopId: string;
      taskId: string;
      traceId: string;
      businessType: 'TOC' | 'TOB';
    }
  ): Promise<{
    timestamp: string;
    metrics: Record<string, any>;
  }> {
    try {
      const timestamp = new Date().toISOString();
      const metrics: Record<string, any> = {};
      
      if (params.metrics.includes('queryCount')) {
        metrics.queryCount = Math.floor(Math.random() * 10000) + 1000;
      }
      if (params.metrics.includes('slowQueryCount')) {
        metrics.slowQueryCount = Math.floor(Math.random() * 100) + 10;
      }
      if (params.metrics.includes('averageQueryTime')) {
        metrics.averageQueryTime = (Math.random() * 500 + 50).toFixed(2);
      }
      if (params.metrics.includes('connectionCount')) {
        metrics.connectionCount = Math.floor(Math.random() * 50) + 5;
      }
      if (params.metrics.includes('bufferPoolUsage')) {
        metrics.bufferPoolUsage = (Math.random() * 80 + 10).toFixed(2);
      }
      
      return {
        timestamp,
        metrics,
      };
    } catch (error) {
      console.error('Error getting database metrics:', error);
      throw new Error('Failed to get database metrics');
    }
  }
}
