#!/usr/bin/env node

/**
 * 性能监控工具
 * 收集和分析测试性能数据，识别性能瓶颈
 */

const fs = require('fs');
const path = require('path');

class PerformanceMonitor {
  constructor() {
    this.performanceDataPath = path.join(process.cwd(), 'test-results', 'performance-data.json');
    this.performanceData = this.loadPerformanceData();
    this.currentSession = {
      startTime: Date.now(),
      tests: [],
      metrics: {}
    };
  }

  loadPerformanceData() {
    try {
      if (fs.existsSync(this.performanceDataPath)) {
        return JSON.parse(fs.readFileSync(this.performanceDataPath, 'utf-8'));
      }
    } catch (error) {
      console.warn('加载性能数据失败:', error.message);
    }
    return {
      sessions: [],
      summary: {
        avgTestTime: 0,
        avgPageLoadTime: 0,
        avgApiTime: 0,
        totalTests: 0,
        slowTests: [],
        fastTests: []
      }
    };
  }

  savePerformanceData() {
    const dir = path.dirname(this.performanceDataPath);
    if (!fs.existsSync(dir)) {
      fs.mkdirSync(dir, { recursive: true });
    }
    fs.writeFileSync(this.performanceDataPath, JSON.stringify(this.performanceData, null, 2), 'utf-8');
  }

  startTest(testName) {
    const test = {
      name: testName,
      startTime: Date.now(),
      metrics: {
        pageLoads: [],
        apiCalls: [],
        domOperations: []
      }
    };
    this.currentSession.tests.push(test);
    return test;
  }

  endTest(test) {
    test.endTime = Date.now();
    test.duration = test.endTime - test.startTime;
    return test;
  }

  recordPageLoad(test, url, loadTime) {
    test.metrics.pageLoads.push({
      url,
      loadTime,
      timestamp: Date.now()
    });
  }

  recordApiCall(test, endpoint, duration) {
    test.metrics.apiCalls.push({
      endpoint,
      duration,
      timestamp: Date.now()
    });
  }

  recordDomOperation(test, operation, duration) {
    test.metrics.domOperations.push({
      operation,
      duration,
      timestamp: Date.now()
    });
  }

  endSession() {
    this.currentSession.endTime = Date.now();
    this.currentSession.duration = this.currentSession.endTime - this.currentSession.startTime;
    
    this.performanceData.sessions.push(this.currentSession);
    this.updateSummary();
    this.savePerformanceData();
    
    return this.currentSession;
  }

  updateSummary() {
    const sessions = this.performanceData.sessions;
    const allTests = sessions.flatMap(s => s.tests);

    if (allTests.length === 0) return;

    const totalDuration = allTests.reduce((sum, t) => sum + t.duration, 0);
    const avgTestTime = totalDuration / allTests.length;

    const allPageLoads = allTests.flatMap(t => t.metrics.pageLoads);
    const avgPageLoadTime = allPageLoads.length > 0
      ? allPageLoads.reduce((sum, p) => sum + p.loadTime, 0) / allPageLoads.length
      : 0;

    const allApiCalls = allTests.flatMap(t => t.metrics.apiCalls);
    const avgApiTime = allApiCalls.length > 0
      ? allApiCalls.reduce((sum, a) => sum + a.duration, 0) / allApiCalls.length
      : 0;

    const sortedTests = [...allTests].sort((a, b) => b.duration - a.duration);
    const slowTests = sortedTests.slice(0, 10);
    const fastTests = sortedTests.slice(-10).reverse();

    this.performanceData.summary = {
      avgTestTime,
      avgPageLoadTime,
      avgApiTime,
      totalTests: allTests.length,
      slowTests: slowTests.map(t => ({
        name: t.name,
        duration: t.duration
      })),
      fastTests: fastTests.map(t => ({
        name: t.name,
        duration: t.duration
      }))
    };
  }

  generateReport() {
    const summary = this.performanceData.summary;
    const sessions = this.performanceData.sessions;

    console.log('');
    console.log('═══════════════════════════════════════════');
    console.log('📊 性能监控报告');
    console.log('═══════════════════════════════════════════');
    console.log('');
    console.log(`📈 总测试数: ${summary.totalTests}`);
    console.log(`⏱️  平均测试时间: ${this.formatDuration(summary.avgTestTime)}`);
    console.log(`🌐 平均页面加载时间: ${this.formatDuration(summary.avgPageLoadTime)}`);
    console.log(`📡 平均API响应时间: ${this.formatDuration(summary.avgApiTime)}`);
    console.log('');

    if (summary.slowTests.length > 0) {
      console.log('🐌 最慢的10个测试:');
      summary.slowTests.forEach((test, index) => {
        console.log(`  ${index + 1}. ${test.name} - ${this.formatDuration(test.duration)}`);
      });
      console.log('');
    }

    if (summary.fastTests.length > 0) {
      console.log('⚡ 最快的10个测试:');
      summary.fastTests.forEach((test, index) => {
        console.log(`  ${index + 1}. ${test.name} - ${this.formatDuration(test.duration)}`);
      });
      console.log('');
    }

    this.analyzePerformanceTrends();
    this.generateRecommendations();
  }

  analyzePerformanceTrends() {
    const sessions = this.performanceData.sessions;
    if (sessions.length < 2) return;

    const recentSessions = sessions.slice(-5);
    const avgDurations = recentSessions.map(s => {
      const tests = s.tests;
      if (tests.length === 0) return 0;
      return tests.reduce((sum, t) => sum + t.duration, 0) / tests.length;
    });

    const trend = this.calculateTrend(avgDurations);
    
    console.log('📈 性能趋势:');
    console.log(`  趋势: ${this.getTrendEmoji(trend)} ${trend.toUpperCase()}`);
    console.log(`  最近5次平均测试时间: ${avgDurations.map(d => this.formatDuration(d)).join(', ')}`);
    console.log('');
  }

  calculateTrend(values) {
    if (values.length < 2) return 'stable';
    
    const firstHalf = values.slice(0, Math.floor(values.length / 2));
    const secondHalf = values.slice(Math.floor(values.length / 2));
    
    const firstAvg = firstHalf.reduce((a, b) => a + b, 0) / firstHalf.length;
    const secondAvg = secondHalf.reduce((a, b) => a + b, 0) / secondHalf.length;
    
    const change = ((secondAvg - firstAvg) / firstAvg) * 100;
    
    if (change < -10) return 'improving';
    if (change > 10) return 'degrading';
    return 'stable';
  }

  generateRecommendations() {
    const summary = this.performanceData.summary;
    const recommendations = [];

    if (summary.avgTestTime > 5000) {
      recommendations.push('⚠️  平均测试时间超过5秒，建议优化测试执行效率');
    }

    if (summary.avgPageLoadTime > 2000) {
      recommendations.push('⚠️  平均页面加载时间超过2秒，建议优化页面性能');
    }

    if (summary.avgApiTime > 1000) {
      recommendations.push('⚠️  平均API响应时间超过1秒，建议优化API性能');
    }

    const slowTestsCount = summary.slowTests.filter(t => t.duration > 10000).length;
    if (slowTestsCount > 5) {
      recommendations.push(`⚠️  有${slowTestsCount}个测试执行时间超过10秒，建议重点优化`);
    }

    if (recommendations.length > 0) {
      console.log('💡 性能优化建议:');
      recommendations.forEach(rec => {
        console.log(`  ${rec}`);
      });
      console.log('');
    }
  }

  getTrendEmoji(trend) {
    switch (trend) {
      case 'improving':
        return '📈';
      case 'degrading':
        return '📉';
      default:
        return '➡️';
    }
  }

  formatDuration(ms) {
    if (ms < 1000) {
      return `${ms}ms`;
    } else if (ms < 60000) {
      return `${(ms / 1000).toFixed(1)}s`;
    } else {
      return `${(ms / 60000).toFixed(1)}m`;
    }
  }

  exportData(filePath) {
    const exportPath = filePath || 'performance-data-export.json';
    fs.writeFileSync(exportPath, JSON.stringify(this.performanceData, null, 2), 'utf-8');
    console.log(`✅ 性能数据已导出到: ${exportPath}`);
  }
}

// 命令行接口
if (require.main === module) {
  const monitor = new PerformanceMonitor();
  const command = process.argv[2];

  switch (command) {
    case 'report':
      monitor.generateReport();
      break;

    case 'export':
      const exportFile = process.argv[3];
      monitor.exportData(exportFile);
      break;

    case 'start':
      const testName = process.argv[3];
      if (testName) {
        const test = monitor.startTest(testName);
        console.log(`✅ 测试已启动: ${testName}`);
        console.log(`测试ID: ${monitor.currentSession.tests.length - 1}`);
      } else {
        console.error('❌ 错误: 请提供测试名称');
        process.exit(1);
      }
      break;

    case 'end':
      const testId = parseInt(process.argv[3]);
      if (!isNaN(testId)) {
        const test = monitor.currentSession.tests[testId];
        if (test) {
          monitor.endTest(test);
          console.log(`✅ 测试已结束: ${test.name}`);
          console.log(`执行时间: ${monitor.formatDuration(test.duration)}`);
        } else {
          console.error('❌ 错误: 测试ID不存在');
          process.exit(1);
        }
      } else {
        console.error('❌ 错误: 请提供有效的测试ID');
        process.exit(1);
      }
      break;

    case 'session':
      monitor.endSession();
      console.log('✅ 测试会话已结束');
      console.log(`会话时长: ${monitor.formatDuration(monitor.currentSession.duration)}`);
      console.log(`测试数量: ${monitor.currentSession.tests.length}`);
      break;

    default:
      console.log('性能监控工具');
      console.log('');
      console.log('用法:');
      console.log('  node performanceMonitor.js report              - 生成性能报告');
      console.log('  node performanceMonitor.js export [file.json]   - 导出性能数据');
      console.log('  node performanceMonitor.js start <testName>    - 启动测试监控');
      console.log('  node performanceMonitor.js end <testId>        - 结束测试监控');
      console.log('  node performanceMonitor.js session               - 结束测试会话');
      console.log('');
      break;
  }
}

module.exports = PerformanceMonitor;