Rendering Pattern

/**
 * Comprehensive Rendering Pattern Framework
 * 
 * This system provides intelligent rendering pattern selection and optimization
 * for modern web applications. Think of it as an adaptive content delivery
 * system that chooses the optimal rendering strategy based on content type,
 * user context, and performance requirements.
 * 
 * Key Capabilities:
 * - Dynamic rendering pattern selection
 * - Optimized hydration strategies
 * - Progressive content delivery
 * - Performance-based pattern adaptation
 * - SEO and accessibility optimization
 */

class RenderingPatternFramework {
  constructor(config = {}) {
    this.config = {
      // Default Rendering Strategy
      defaultPattern: config.defaultPattern || 'hybrid',
      enableAdaptiveRendering: config.enableAdaptiveRendering !== false,
      
      // Pattern Configuration
      patterns: {
        csr: {
          enabled: config.enableCSR !== false,
          bundleStrategy: 'lazy-loading',
          hydrationStrategy: 'progressive'
        },
        ssr: {
          enabled: config.enableSSR !== false,
          cachingStrategy: 'edge-cache',
          streamingEnabled: config.enableStreaming !== false
        },
        ssg: {
          enabled: config.enableSSG !== false,
          regenerationStrategy: 'on-demand',
          fallbackStrategy: 'ssr'
        },
        isr: {
          enabled: config.enableISR !== false,
          revalidationInterval: config.revalidationInterval || 60,
          staleWhileRevalidate: config.staleWhileRevalidate !== false
        }
      },
      
      // Performance Optimization
      hydrationOptimization: {
        enableSelectiveHydration: config.enableSelectiveHydration !== false,
        enableProgressiveHydration: config.enableProgressiveHydration !== false,
        priorityHydration: config.priorityHydration || 'viewport-first'
      },
      
      // SEO and Accessibility
      seoOptimization: {
        enableStructuredData: config.enableStructuredData !== false,
        enableOpenGraph: config.enableOpenGraph !== false,
        enableTwitterCards: config.enableTwitterCards !== false
      },
      
      // Performance Monitoring
      performanceTracking: {
        enabled: config.enablePerformanceTracking !== false,
        coreWebVitals: true,
        renderingMetrics: true
      },
      
      ...config
    };

    // Initialize rendering components
    this.patternSelector = new RenderingPatternSelector(this.config);
    this.hydrationManager = new HydrationOptimizationManager(this.config);
    this.contentStreamer = new ContentStreamingManager(this.config);
    this.seoOptimizer = new SEORenderingOptimizer(this.config);
    this.performanceMonitor = new RenderingPerformanceMonitor(this.config);
    
    // Pattern-specific renderers
    this.csrRenderer = new ClientSideRenderer(this.config);
    this.ssrRenderer = new ServerSideRenderer(this.config);
    this.ssgRenderer = new StaticSiteGenerator(this.config);
    this.isrRenderer = new IncrementalStaticRegenerator(this.config);
    
    // Internal state management
    this.renderingCache = new Map();
    this.performanceMetrics = new Map();
    this.patternPerformance = new Map();
    
    this.initialize();
  }

  initialize() {
    // Set up adaptive rendering based on performance data
    this.setupAdaptiveRendering();
    
    // Initialize performance monitoring
    this.initializePerformanceTracking();
    
    // Configure SEO optimization
    this.setupSEOOptimization();
    
    // Set up hydration optimization
    this.initializeHydrationOptimization();
  }

  /**
   * Intelligent Rendering Pattern Selection
   * 
   * This system analyzes request context, content characteristics, and
   * performance requirements to select the optimal rendering pattern
   * for each page or component. Think of it as a traffic controller
   * that routes content through the most efficient rendering pipeline.
   * 
   * Selection Factors:
   * - Content type and update frequency
   * - User context (first visit vs. returning user)
   * - Device capabilities and network conditions
   * - SEO requirements and search bot detection
   * - Performance constraints and business requirements
   */
  async selectRenderingPattern(request, contentInfo) {
    const selectionContext = {
      request: this.analyzeRequest(request),
      content: this.analyzeContent(contentInfo),
      performance: await this.getPerformanceContext(request),
      business: this.getBusinessRequirements(contentInfo)
    };

    // Pattern selection algorithm
    const patternScores = await this.scoreRenderingPatterns(selectionContext);
    const optimalPattern = this.selectOptimalPattern(patternScores);
    
    return {
      pattern: optimalPattern,
      reasoning: this.explainPatternSelection(patternScores),
      optimizations: await this.getPatternOptimizations(optimalPattern, selectionContext),
      fallback: this.determineFallbackPattern(optimalPattern)
    };
  }

  async scoreRenderingPatterns(context) {
    const scores = {
      csr: await this.scoreCSRPattern(context),
      ssr: await this.scoreSSRPattern(context),
      ssg: await this.scoreSSGPattern(context),
      isr: await this.scoreISRPattern(context),
      hybrid: await this.scoreHybridPattern(context)
    };

    return scores;
  }

  async scoreCSRPattern(context) {
    const score = {
      performance: 0,
      seo: 0,
      infrastructure: 0,
      development: 0,
      total: 0
    };

    // Performance scoring
    if (context.content.interactivityHeavy) {
      score.performance += 8; // CSR excels at interactive applications
    }
    
    if (context.request.isReturningUser) {
      score.performance += 6; // Cached bundles improve subsequent visits
    }
    
    if (context.request.networkSpeed === 'fast') {
      score.performance += 5; // Fast networks can handle bundle downloads
    } else {
      score.performance -= 3; // Slow networks struggle with large bundles
    }

    // SEO scoring
    if (context.content.seoRequired) {
      score.seo -= 8; // CSR has poor SEO by default
    }
    
    if (context.request.isSearchBot) {
      score.seo -= 10; // Search bots struggle with CSR content
    }

    // Infrastructure scoring
    score.infrastructure += 9; // Excellent infrastructure efficiency
    
    // Development scoring
    if (context.content.contentType === 'spa') {
      score.development += 8; // Natural fit for SPA development
    }

    score.total = (score.performance + score.seo + score.infrastructure + score.development) / 4;
    
    return score;
  }

  async scoreSSRPattern(context) {
    const score = {
      performance: 0,
      seo: 0,
      infrastructure: 0,
      development: 0,
      total: 0
    };

    // Performance scoring
    if (context.request.isFirstVisit) {
      score.performance += 8; // Excellent initial load performance
    }
    
    if (context.request.deviceCapability === 'low') {
      score.performance += 6; // Reduces client-side processing
    }
    
    if (context.content.dynamicContent) {
      score.performance += 7; // Great for dynamic content
    }

    // SEO scoring
    score.seo += 9; // Excellent SEO with immediate HTML content
    
    if (context.request.isSearchBot) {
      score.seo += 10; // Perfect for search bots
    }

    // Infrastructure scoring
    score.infrastructure -= 4; // Requires server processing power
    
    if (context.business.trafficVolume === 'high') {
      score.infrastructure -= 3; // Challenging to scale for high traffic
    }

    // Development scoring
    if (context.content.realTimeData) {
      score.development += 6; // Good for real-time content
    }
    
    score.total = (score.performance + score.seo + score.infrastructure + score.development) / 4;
    
    return score;
  }

  async scoreSSGPattern(context) {
    const score = {
      performance: 0,
      seo: 0,
      infrastructure: 0,
      development: 0,
      total: 0
    };

    // Performance scoring
    score.performance += 10; // Excellent performance characteristics
    
    if (context.content.updateFrequency === 'low') {
      score.performance += 8; // Perfect for infrequently updated content
    }
    
    if (context.content.updateFrequency === 'high') {
      score.performance -= 6; // Poor for frequently updated content
    }

    // SEO scoring
    score.seo += 10; // Perfect SEO with static HTML
    
    // Infrastructure scoring
    score.infrastructure += 10; // Minimal infrastructure requirements
    
    // Development scoring
    if (context.content.contentType === 'blog' || context.content.contentType === 'documentation') {
      score.development += 9; // Perfect for content-focused sites
    }
    
    if (context.content.userGeneratedContent) {
      score.development -= 5; // Challenging for user-generated content
    }

    score.total = (score.performance + score.seo + score.infrastructure + score.development) / 4;
    
    return score;
  }

  async scoreISRPattern(context) {
    const score = {
      performance: 0,
      seo: 0,
      infrastructure: 0,
      development: 0,
      total: 0
    };

    // Performance scoring
    score.performance += 9; // Near-static performance with fresh content
    
    if (context.content.updateFrequency === 'medium') {
      score.performance += 8; // Perfect sweet spot for ISR
    }

    // SEO scoring
    score.seo += 9; // Excellent SEO with fresh static content
    
    // Infrastructure scoring
    score.infrastructure += 7; // Good infrastructure efficiency with selective regeneration
    
    // Development scoring
    if (context.content.contentType === 'ecommerce' || context.content.contentType === 'news') {
      score.development += 8; // Great for commerce and news sites
    }

    score.total = (score.performance + score.seo + score.infrastructure + score.development) / 4;
    
    return score;
  }

  /**
   * Advanced Server-Side Rendering with Streaming
   * 
   * Modern SSR implementations use streaming to improve perceived performance
   * by sending content to users as it's generated rather than waiting for
   * the complete page to render. This significantly improves Time to First Byte
   * and First Contentful Paint metrics.
   * 
   * Streaming Benefits:
   * - Improved TTFB (Time to First Byte)
   * - Better FCP (First Contentful Paint)
   * - Progressive content delivery
   * - Better handling of slow data sources
   */
  async renderWithServerSideStreaming(request, components) {
    const streamingContext = {
      request,
      components: this.analyzeComponentPriority(components),
      performance: await this.getStreamingPerformanceContext()
    };

    return this.ssrRenderer.renderStreamable(streamingContext);
  }

  analyzeComponentPriority(components) {
    return components.map(component => {
      const analysis = {
        component,
        priority: this.calculateComponentPriority(component),
        renderingStrategy: this.determineComponentRenderingStrategy(component),
        dependencies: this.extractComponentDependencies(component),
        estimatedRenderTime: this.estimateComponentRenderTime(component)
      };

      return analysis;
    }).sort((a, b) => b.priority - a.priority);
  }

  calculateComponentPriority(component) {
    let priority = 0;
    
    // Above-the-fold components get highest priority
    if (component.aboveTheFold) {
      priority += 100;
    }
    
    // Critical UI components
    if (component.type === 'navigation' || component.type === 'header') {
      priority += 80;
    }
    
    // Content components
    if (component.type === 'content' || component.type === 'hero') {
      priority += 70;
    }
    
    // Interactive components
    if (component.interactive) {
      priority += 50;
    }
    
    // Footer and non-critical components
    if (component.type === 'footer' || component.type === 'sidebar') {
      priority += 20;
    }
    
    return priority;
  }

  /**
   * Progressive and Selective Hydration Optimization
   * 
   * Hydration is often the bottleneck in SSR applications. Progressive hydration
   * allows components to become interactive incrementally, while selective
   * hydration only hydrates components that require interactivity.
   * 
   * Hydration Strategies:
   * - Selective: Only hydrate interactive components
   * - Progressive: Hydrate in priority order
   * - On-demand: Hydrate when user interaction is detected
   * - Viewport-based: Hydrate when components enter viewport
   */
  async optimizeHydration(renderingResult, hydrationConfig) {
    const hydrationPlan = {
      strategy: hydrationConfig.strategy || 'progressive',
      phases: [],
      performance: {},
      monitoring: {}
    };

    // Analyze components for hydration requirements
    const componentAnalysis = this.analyzeComponentsForHydration(renderingResult.components);
    
    // Create hydration phases based on priority and dependencies
    hydrationPlan.phases = this.createHydrationPhases(componentAnalysis, hydrationConfig);
    
    // Implement the hydration strategy
    return this.executeHydrationPlan(hydrationPlan);
  }

  analyzeComponentsForHydration(components) {
    return components.map(component => {
      const analysis = {
        component,
        requiresHydration: this.componentRequiresHydration(component),
        interactivityType: this.getComponentInteractivityType(component),
        hydrationPriority: this.calculateHydrationPriority(component),
        dependencies: this.getHydrationDependencies(component),
        estimatedHydrationTime: this.estimateHydrationTime(component)
      };

      return analysis;
    });
  }

  componentRequiresHydration(component) {
    // Static components don't need hydration
    if (component.static) return false;
    
    // Components with event handlers need hydration
    if (component.eventHandlers && component.eventHandlers.length > 0) return true;
    
    // Components with state need hydration
    if (component.hasState) return true;
    
    // Components with side effects need hydration
    if (component.sideEffects) return true;
    
    return false;
  }

  createHydrationPhases(componentAnalysis, config) {
    const phases = [];
    
    // Phase 1: Critical interactive components (navigation, forms)
    const criticalComponents = componentAnalysis.filter(c => 
      c.requiresHydration && 
      (c.interactivityType === 'critical' || c.component.aboveTheFold)
    );
    
    if (criticalComponents.length > 0) {
      phases.push({
        name: 'critical',
        components: criticalComponents,
        timing: 'immediate',
        strategy: 'parallel'
      });
    }

    // Phase 2: Above-the-fold interactive components
    const aboveFoldComponents = componentAnalysis.filter(c => 
      c.requiresHydration && 
      c.component.aboveTheFold && 
      c.interactivityType !== 'critical'
    );
    
    if (aboveFoldComponents.length > 0) {
      phases.push({
        name: 'above-fold',
        components: aboveFoldComponents,
        timing: 'early',
        strategy: 'sequential'
      });
    }

    // Phase 3: Viewport-triggered components
    const viewportComponents = componentAnalysis.filter(c => 
      c.requiresHydration && 
      !c.component.aboveTheFold &&
      c.interactivityType === 'on-demand'
    );
    
    if (viewportComponents.length > 0) {
      phases.push({
        name: 'viewport',
        components: viewportComponents,
        timing: 'intersection',
        strategy: 'lazy'
      });
    }

    // Phase 4: Low-priority components
    const lowPriorityComponents = componentAnalysis.filter(c => 
      c.requiresHydration && 
      c.hydrationPriority < 50
    );
    
    if (lowPriorityComponents.length > 0) {
      phases.push({
        name: 'low-priority',
        components: lowPriorityComponents,
        timing: 'idle',
        strategy: 'background'
      });
    }

    return phases;
  }

  /**
   * Incremental Static Regeneration (ISR) Implementation
   * 
   * ISR provides the performance benefits of static generation with the
   * freshness of server-side rendering. It regenerates static pages in
   * the background based on configurable revalidation intervals.
   * 
   * ISR Benefits:
   * - Static performance for most requests
   * - Fresh content without rebuild delays
   * - Selective regeneration based on usage
   * - Graceful fallback to stale content
   */
  async implementIncrementalStaticRegeneration(pageConfig) {
    const isrConfig = {
      revalidate: pageConfig.revalidate || 60, // Revalidate every 60 seconds
      fallback: pageConfig.fallback || 'blocking',
      onDemandRevalidation: pageConfig.onDemandRevalidation !== false,
      staleWhileRevalidate: pageConfig.staleWhileRevalidate !== false
    };

    return this.isrRenderer.configure(isrConfig);
  }

  async handleISRRequest(request, pageConfig) {
    const cachedVersion = await this.isrRenderer.getCachedVersion(request.path);
    const currentTime = Date.now();
    
    // Check if cached version exists and is still valid
    if (cachedVersion && 
        (currentTime - cachedVersion.generatedAt) < (pageConfig.revalidate * 1000)) {
      
      // Serve cached version immediately
      return {
        content: cachedVersion.content,
        headers: {
          'Cache-Control': `s-maxage=${pageConfig.revalidate}, stale-while-revalidate`,
          'X-Cache-Status': 'HIT'
        }
      };
    }

    // Handle stale content with background regeneration
    if (cachedVersion && pageConfig.staleWhileRevalidate) {
      // Serve stale content immediately
      const response = {
        content: cachedVersion.content,
        headers: {
          'Cache-Control': `s-maxage=${pageConfig.revalidate}, stale-while-revalidate`,
          'X-Cache-Status': 'STALE'
        }
      };

      // Trigger background regeneration
      this.isrRenderer.regenerateInBackground(request.path, pageConfig);
      
      return response;
    }

    // No cached version or blocking fallback - generate fresh content
    const freshContent = await this.isrRenderer.generateFreshContent(request, pageConfig);
    
    return {
      content: freshContent,
      headers: {
        'Cache-Control': `s-maxage=${pageConfig.revalidate}`,
        'X-Cache-Status': 'MISS'
      }
    };
  }

  /**
   * Performance Monitoring and Adaptive Optimization
   * 
   * Continuous monitoring of rendering performance enables adaptive
   * optimization where rendering patterns adjust based on actual
   * performance data and user experience metrics.
   */
  async monitorRenderingPerformance(renderingResult, pattern) {
    const performanceMetrics = {
      pattern,
      timestamp: Date.now(),
      metrics: {
        serverTime: renderingResult.serverRenderTime,
        hydrationTime: renderingResult.hydrationTime,
        totalTime: renderingResult.totalTime,
        coreWebVitals: await this.collectCoreWebVitals(),
        userExperienceMetrics: await this.collectUXMetrics()
      },
      context: {
        userAgent: renderingResult.userAgent,
        networkCondition: renderingResult.networkCondition,
        deviceType: renderingResult.deviceType
      }
    };

    // Store metrics for analysis
    this.performanceMonitor.record(performanceMetrics);
    
    // Trigger adaptive optimization if performance degrades
    if (this.shouldAdaptPattern(performanceMetrics)) {
      await this.adaptRenderingPattern(performanceMetrics);
    }

    return performanceMetrics;
  }

  shouldAdaptPattern(metrics) {
    // Check if Core Web Vitals are failing
    if (metrics.metrics.coreWebVitals.lcp > 2500 || 
        metrics.metrics.coreWebVitals.fid > 100 ||
        metrics.metrics.coreWebVitals.cls > 0.1) {
      return true;
    }

    // Check if server rendering time is too high
    if (metrics.metrics.serverTime > 1000) {
      return true;
    }

    // Check if hydration is taking too long
    if (metrics.metrics.hydrationTime > 500) {
      return true;
    }

    return false;
  }

  async adaptRenderingPattern(performanceMetrics) {
    const currentPattern = performanceMetrics.pattern;
    const adaptationStrategy = await this.determineAdaptationStrategy(performanceMetrics);
    
    switch (adaptationStrategy.type) {
      case 'fallback-to-csr':
        return this.fallbackToCSR(adaptationStrategy.reason);
      
      case 'enable-streaming':
        return this.enableStreamingSSR(adaptationStrategy.config);
      
      case 'optimize-hydration':
        return this.optimizeHydrationStrategy(adaptationStrategy.optimizations);
      
      case 'increase-cache-ttl':
        return this.increaseCacheTTL(adaptationStrategy.newTTL);
      
      default:
        return this.logAdaptationDecision(adaptationStrategy);
    }
  }

  // Utility methods for rendering pattern analysis
  analyzeRequest(request) {
    return {
      userAgent: request.headers['user-agent'],
      isFirstVisit: !request.cookies.returning_user,
      isReturningUser: !!request.cookies.returning_user,
      isSearchBot: this.isSearchBot(request.headers['user-agent']),
      networkSpeed: this.estimateNetworkSpeed(request),
      deviceCapability: this.estimateDeviceCapability(request.headers['user-agent'])
    };
  }

  analyzeContent(contentInfo) {
    return {
      contentType: contentInfo.type,
      updateFrequency: contentInfo.updateFrequency,
      seoRequired: contentInfo.seoRequired,
      interactivityHeavy: contentInfo.interactiveComponents > 5,
      dynamicContent: contentInfo.requiresRealTimeData,
      userGeneratedContent: contentInfo.hasUserContent
    };
  }

  isSearchBot(userAgent) {
    const botPatterns = [
      /googlebot/i,
      /bingbot/i,
      /slurp/i,
      /duckduckbot/i,
      /baiduspider/i,
      /yandexbot/i,
      /facebookexternalhit/i,
      /twitterbot/i,
      /linkedinbot/i
    ];

    return botPatterns.some(pattern => pattern.test(userAgent));
  }
}

// Pattern-specific renderer implementations
class ServerSideRenderer {
  async renderStreamable(context) {
    const stream = new ReadableStream({
      start(controller) {
        this.streamComponents(context.components, controller);
      }
    });

    return {
      stream,
      headers: {
        'Content-Type': 'text/html; charset=utf-8',
        'Transfer-Encoding': 'chunked'
      }
    };
  }

  async streamComponents(components, controller) {
    // Send HTML shell immediately
    controller.enqueue(this.generateHTMLShell());
    
    // Stream components by priority
    for (const componentAnalysis of components) {
      const renderedComponent = await this.renderComponent(componentAnalysis.component);
      controller.enqueue(renderedComponent);
      
      // Allow other operations between component renders
      await this.yield();
    }
    
    controller.enqueue(this.generateHTMLFooter());
    controller.close();
  }

  yield() {
    return new Promise(resolve => setTimeout(resolve, 0));
  }
}

// Usage Examples
const renderingFramework = new RenderingPatternFramework({
  defaultPattern: 'hybrid',
  enableAdaptiveRendering: true,
  enableStreaming: true,
  enableSelectiveHydration: true,
  revalidationInterval: 300 // 5 minutes for ISR
});

// Example: Adaptive rendering based on content and user context
async function renderPage(request, pageInfo) {
  const patternSelection = await renderingFramework.selectRenderingPattern(request, pageInfo);
  
  let renderingResult;
  
  switch (patternSelection.pattern) {
    case 'ssr':
      renderingResult = await renderingFramework.renderWithServerSideStreaming(request, pageInfo.components);
      break;
    case 'isr':
      renderingResult = await renderingFramework.handleISRRequest(request, pageInfo.isrConfig);
      break;
    case 'csr':
      renderingResult = await renderingFramework.csrRenderer.render(pageInfo);
      break;
    default:
      renderingResult = await renderingFramework.renderHybrid(request, pageInfo);
  }
  
  // Monitor and adapt based on performance
  await renderingFramework.monitorRenderingPerformance(renderingResult, patternSelection.pattern);
  
  return renderingResult;
}

export { RenderingPatternFramework };

async scoreRenderingPatterns(context) {
  const scores = {
    csr: await this.scoreCSRPattern(context),
    ssr: await this.scoreSSRPattern(context),
    ssg: await this.scoreSSGPattern(context),
    isr: await this.scoreISRPattern(context)
  };

  // Each pattern scored across multiple dimensions
  return scores;
}

async scoreSSRPattern(context) {
  const score = { performance: 0, seo: 0, infrastructure: 0, development: 0 };

  // Performance scoring based on context
  if (context.request.isFirstVisit) {
    score.performance += 8;  // Excellent initial load performance
  }
  
  if (context.content.dynamicContent) {
    score.performance += 7;  // Great for dynamic content
  }

  // SEO scoring
  score.seo += 9;  // Excellent SEO with immediate HTML content
  if (context.request.isSearchBot) {
    score.seo += 10;  // Perfect for search bots
  }

  return score;
}

analyzeComponentPriority(components) {
  return components.map(component => {
    const priority = this.calculateComponentPriority(component);
    
    // Above-the-fold components get highest priority
    if (component.aboveTheFold) priority += 100;
    
    // Critical UI components (navigation, header)
    if (component.type === 'navigation') priority += 80;
    
    // Content components
    if (component.type === 'content') priority += 70;
    
    return { component, priority };
  }).sort((a, b) => b.priority - a.priority);
}

async streamComponents(components, controller) {
  // Send HTML shell immediately for fast TTFB
  controller.enqueue(this.generateHTMLShell());
  
  // Stream components by priority order
  for (const componentAnalysis of components) {
    const renderedComponent = await this.renderComponent(componentAnalysis.component);
    controller.enqueue(renderedComponent);
    
    // Yield control for other operations
    await this.yield();
  }
  
  controller.close();
}

createHydrationPhases(componentAnalysis, config) {
  const phases = [];
  
  // Phase 1: Critical interactive components (immediate)
  const criticalComponents = componentAnalysis.filter(c => 
    c.requiresHydration && c.interactivityType === 'critical'
  );
  
  phases.push({
    name: 'critical',
    components: criticalComponents,
    timing: 'immediate',
    strategy: 'parallel'
  });

  // Phase 2: Above-the-fold components (early)
  const aboveFoldComponents = componentAnalysis.filter(c => 
    c.requiresHydration && c.component.aboveTheFold
  );
  
  phases.push({
    name: 'above-fold',
    components: aboveFoldComponents,
    timing: 'early',
    strategy: 'sequential'
  });

  // Phase 3: Viewport-triggered components (lazy)
  const viewportComponents = componentAnalysis.filter(c => 
    c.requiresHydration && c.interactivityType === 'on-demand'
  );
  
  phases.push({
    name: 'viewport',
    components: viewportComponents,
    timing: 'intersection',
    strategy: 'lazy'
  });

  return phases;
}

async handleISRRequest(request, pageConfig) {
  const cachedVersion = await this.getCachedVersion(request.path);
  const currentTime = Date.now();
  
  // Check if cached version is still valid
  if (cachedVersion && 
      (currentTime - cachedVersion.generatedAt) < (pageConfig.revalidate * 1000)) {
    
    // Serve fresh cached version
    return {
      content: cachedVersion.content,
      headers: { 'X-Cache-Status': 'HIT' }
    };
  }

  // Handle stale-while-revalidate pattern
  if (cachedVersion && pageConfig.staleWhileRevalidate) {
    // Serve stale content immediately
    const response = {
      content: cachedVersion.content,
      headers: { 'X-Cache-Status': 'STALE' }
    };

    // Trigger background regeneration for next request
    this.regenerateInBackground(request.path, pageConfig);
    
    return response;
  }

  // Generate fresh content for cache miss
  const freshContent = await this.generateFreshContent(request, pageConfig);
  return { content: freshContent, headers: { 'X-Cache-Status': 'MISS' } };
}

shouldAdaptPattern(metrics) {
  // Check Core Web Vitals thresholds
  if (metrics.coreWebVitals.lcp > 2500 ||    // LCP > 2.5s is poor
      metrics.coreWebVitals.fid > 100 ||     // FID > 100ms is poor  
      metrics.coreWebVitals.cls > 0.1) {     // CLS > 0.1 is poor
    return true;
  }

  // Check rendering-specific metrics
  if (metrics.serverTime > 1000) {          // Server rendering too slow
    return true;
  }
  
  if (metrics.hydrationTime > 500) {        // Hydration blocking too long
    return true;
  }

  return false;
}

async adaptRenderingPattern(metrics) {
  const adaptationStrategy = await this.determineAdaptationStrategy(metrics);
  
  switch (adaptationStrategy.type) {
    case 'fallback-to-csr':
      return this.fallbackToCSR('SSR performance degraded');
    
    case 'enable-streaming':
      return this.enableStreamingSSR({ chunkSize: 8192 });
    
    case 'optimize-hydration':
      return this.optimizeHydrationStrategy({ 
        enableSelectiveHydration: true,
        priorityThreshold: 80
      });
  }
}