import { DomainEventBus } from '../runtime/DomainEventBus';
import { ExceptionInfo } from './ExceptionMonitor';

// 异常处理策略
export interface ExceptionHandlingStrategy {
  id: string;
  name: string;
  description: string;
  exceptionType: string;
  severity: 'low' | 'medium' | 'high' | 'critical';
  actions: ExceptionAction[];
  enabled: boolean;
  createdAt: Date;
  lastUpdated: Date;
}

// 异常处理动作
export interface ExceptionAction {
  type: 'retry' | 'fallback' | 'alert' | 'auto-fix' | 'escalate';
  parameters?: Record<string, any>;
  order: number;
}

// 异常处理结果
export interface ExceptionHandlingResult {
  id: string;
  exceptionId: string;
  strategyId: string;
  actions: {
    type: string;
    success: boolean;
    message: string;
    timestamp: Date;
  }[];
  overallStatus: 'success' | 'partial' | 'failure';
  timestamp: Date;
}

// 智能异常处理
export class IntelligentExceptionHandler {
  private static instance: IntelligentExceptionHandler;
  private strategies: Map<string, ExceptionHandlingStrategy> = new Map();
  private handlingResults: Map<string, ExceptionHandlingResult> = new Map();
  private eventBus: DomainEventBus;

  private constructor() {
    this.eventBus = DomainEventBus.getInstance();
  }

  static getInstance(): IntelligentExceptionHandler {
    if (!IntelligentExceptionHandler.instance) {
      IntelligentExceptionHandler.instance = new IntelligentExceptionHandler();
    }
    return IntelligentExceptionHandler.instance;
  }

  // 创建异常处理策略
  async createStrategy(strategy: Omit<ExceptionHandlingStrategy, 'id' | 'createdAt' | 'lastUpdated'>): Promise<ExceptionHandlingStrategy> {
    const id = `strategy_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
    
    const newStrategy: ExceptionHandlingStrategy = {
      ...strategy,
      id,
      createdAt: new Date(),
      lastUpdated: new Date()
    };

    this.strategies.set(id, newStrategy);
    this.eventBus.publish('exception.strategy.created', newStrategy);
    return newStrategy;
  }

  // 获取异常处理策略
  getStrategy(strategyId: string): ExceptionHandlingStrategy | undefined {
    return this.strategies.get(strategyId);
  }

  // 获取所有异常处理策略
  getAllStrategies(filters?: {
    exceptionType?: string;
    severity?: string;
    enabled?: boolean;
  }): ExceptionHandlingStrategy[] {
    let result = Array.from(this.strategies.values());

    if (filters) {
      if (filters.exceptionType) {
        result = result.filter(s => s.exceptionType === filters.exceptionType);
      }

      if (filters.severity) {
        result = result.filter(s => s.severity === filters.severity);
      }

      if (filters.enabled !== undefined) {
        result = result.filter(s => s.enabled === filters.enabled);
      }
    }

    return result;
  }

  // 更新异常处理策略
  async updateStrategy(strategyId: string, updates: Partial<ExceptionHandlingStrategy>): Promise<ExceptionHandlingStrategy | null> {
    const strategy = this.strategies.get(strategyId);
    if (!strategy) {
      return null;
    }

    const updatedStrategy = {
      ...strategy,
      ...updates,
      lastUpdated: new Date()
    };

    this.strategies.set(strategyId, updatedStrategy);
    this.eventBus.publish('exception.strategy.updated', updatedStrategy);
    return updatedStrategy;
  }

  // 启用/禁用异常处理策略
  async toggleStrategy(strategyId: string, enabled: boolean): Promise<boolean> {
    const strategy = this.strategies.get(strategyId);
    if (!strategy) {
      return false;
    }

    strategy.enabled = enabled;
    strategy.lastUpdated = new Date();
    this.strategies.set(strategyId, strategy);
    this.eventBus.publish('exception.strategy.toggled', strategy);
    return true;
  }

  // 处理异常
  async handleException(exception: ExceptionInfo): Promise<ExceptionHandlingResult> {
    // 查找匹配的策略
    const strategies = this.getAllStrategies({ 
      exceptionType: exception.type, 
      enabled: true 
    });

    // 按严重性排序，选择最匹配的策略
    strategies.sort((a, b) => {
      const severityOrder = { critical: 4, high: 3, medium: 2, low: 1 };
      return severityOrder[b.severity] - severityOrder[a.severity];
    });

    const strategy = strategies[0];
    const actions: ExceptionHandlingResult['actions'] = [];
    let overallStatus: 'success' | 'partial' | 'failure' = 'failure';

    if (strategy) {
      // 按顺序执行策略中的动作
      const sortedActions = [...strategy.actions].sort((a, b) => a.order - b.order);
      let successCount = 0;

      for (const action of sortedActions) {
        const result = await this.executeAction(action, exception);
        actions.push(result);
        if (result.success) {
          successCount++;
        }
      }

      if (successCount === sortedActions.length) {
        overallStatus = 'success';
      } else if (successCount > 0) {
        overallStatus = 'partial';
      }
    } else {
      // 默认动作：告警
      const result = await this.executeAction({ 
        type: 'alert', 
        order: 1 
      }, exception);
      actions.push(result);
      overallStatus = result.success ? 'success' : 'failure';
    }

    const handlingResult: ExceptionHandlingResult = {
      id: `result_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
      exceptionId: exception.id,
      strategyId: strategy?.id || 'default',
      actions,
      overallStatus,
      timestamp: new Date()
    };

    this.handlingResults.set(handlingResult.id, handlingResult);
    this.eventBus.publish('exception.handled', handlingResult);
    return handlingResult;
  }

  // 执行异常处理动作
  private async executeAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    try {
      switch (action.type) {
        case 'retry':
          return await this.executeRetryAction(action, exception);
        case 'fallback':
          return await this.executeFallbackAction(action, exception);
        case 'alert':
          return await this.executeAlertAction(action, exception);
        case 'auto-fix':
          return await this.executeAutoFixAction(action, exception);
        case 'escalate':
          return await this.executeEscalateAction(action, exception);
        default:
          return {
            type: action.type,
            success: false,
            message: `Unknown action type: ${action.type}`,
            timestamp: new Date()
          };
      }
    } catch (error) {
      return {
        type: action.type,
        success: false,
        message: error instanceof Error ? error.message : 'Unknown error',
        timestamp: new Date()
      };
    }
  }

  // 执行重试动作
  private async executeRetryAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    const maxRetries = action.parameters?.maxRetries || 3;
    const delayMs = action.parameters?.delayMs || 1000;

    for (let i = 0; i < maxRetries; i++) {
      try {
        // 这里应该有实际的重试逻辑
        // 暂时模拟重试
        await new Promise(resolve => setTimeout(resolve, delayMs));
        
        const success = Math.random() > 0.3; // 70% 成功率
        if (success) {
          return {
            type: 'retry',
            success: true,
            message: `Successfully retried after ${i + 1} attempt(s)`,
            timestamp: new Date()
          };
        }
      } catch (error) {
        // 重试失败，继续下一次
      }
    }

    return {
      type: 'retry',
      success: false,
      message: `Failed after ${maxRetries} attempts`,
      timestamp: new Date()
    };
  }

  // 执行回退动作
  private async executeFallbackAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    // 这里应该有实际的回退逻辑
    // 暂时模拟回退
    await new Promise(resolve => setTimeout(resolve, 500));

    return {
      type: 'fallback',
      success: true,
      message: 'Fallback executed successfully',
      timestamp: new Date()
    };
  }

  // 执行告警动作
  private async executeAlertAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    // 这里应该有实际的告警逻辑
    // 暂时模拟告警
    await new Promise(resolve => setTimeout(resolve, 200));

    this.eventBus.publish('exception.alert', {
      exception,
      timestamp: new Date()
    });

    return {
      type: 'alert',
      success: true,
      message: 'Alert sent successfully',
      timestamp: new Date()
    };
  }

  // 执行自动修复动作
  private async executeAutoFixAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    // 这里应该有实际的自动修复逻辑
    // 暂时模拟自动修复
    await new Promise(resolve => setTimeout(resolve, 1000));

    const success = Math.random() > 0.2; // 80% 成功率
    return {
      type: 'auto-fix',
      success,
      message: success ? 'Auto-fix executed successfully' : 'Auto-fix failed',
      timestamp: new Date()
    };
  }

  // 执行升级动作
  private async executeEscalateAction(action: ExceptionAction, exception: ExceptionInfo): Promise<ExceptionHandlingResult['actions'][0]> {
    // 这里应该有实际的升级逻辑
    // 暂时模拟升级
    await new Promise(resolve => setTimeout(resolve, 300));

    this.eventBus.publish('exception.escalated', {
      exception,
      timestamp: new Date()
    });

    return {
      type: 'escalate',
      success: true,
      message: 'Exception escalated successfully',
      timestamp: new Date()
    };
  }

  // 获取异常处理结果
  getHandlingResult(resultId: string): ExceptionHandlingResult | undefined {
    return this.handlingResults.get(resultId);
  }

  // 获取异常的处理结果
  getExceptionHandlingResults(exceptionId: string): ExceptionHandlingResult[] {
    return Array.from(this.handlingResults.values()).filter(r => r.exceptionId === exceptionId);
  }

  // 获取策略的处理结果
  getStrategyHandlingResults(strategyId: string): ExceptionHandlingResult[] {
    return Array.from(this.handlingResults.values()).filter(r => r.strategyId === strategyId);
  }

  // 批量处理异常
  async batchHandleExceptions(exceptionIds: string[], exceptionMonitor: any): Promise<ExceptionHandlingResult[]> {
    const results: ExceptionHandlingResult[] = [];

    for (const exceptionId of exceptionIds) {
      const exception = exceptionMonitor.getException(exceptionId);
      if (exception) {
        const result = await this.handleException(exception);
        results.push(result);
      }
    }

    return results;
  }

  // 生成异常处理报告
  async generateHandlingReport(startDate: Date, endDate: Date): Promise<{
    summary: {
      totalExceptions: number;
      successfullyHandled: number;
      partiallyHandled: number;
      failedHandled: number;
      mostUsedStrategies: string[];
    };
    details: ExceptionHandlingResult[];
  }> {
    const filteredResults = Array.from(this.handlingResults.values()).filter(
      r => r.timestamp >= startDate && r.timestamp <= endDate
    );

    const successfullyHandled = filteredResults.filter(r => r.overallStatus === 'success').length;
    const partiallyHandled = filteredResults.filter(r => r.overallStatus === 'partial').length;
    const failedHandled = filteredResults.filter(r => r.overallStatus === 'failure').length;

    // 统计最常用的策略
    const strategyUsage: Record<string, number> = {};
    for (const result of filteredResults) {
      strategyUsage[result.strategyId] = (strategyUsage[result.strategyId] || 0) + 1;
    }

    const mostUsedStrategies = Object.entries(strategyUsage)
      .sort(([, a], [, b]) => b - a)
      .slice(0, 5)
      .map(([strategyId]) => strategyId);

    return {
      summary: {
        totalExceptions: filteredResults.length,
        successfullyHandled,
        partiallyHandled,
        failedHandled,
        mostUsedStrategies
      },
      details: filteredResults
    };
  }
}
