/**
 * Utilitários para otimização de performance
 */

// Cache otimizado com LRU (Least Recently Used)
export class LRUCache<K, V> {
  private cache = new Map<K, V>();
  private readonly maxSize: number;

  constructor(maxSize: number = 100) {
    this.maxSize = maxSize;
  }

  get(key: K): V | undefined {
    const value = this.cache.get(key);
    if (value !== undefined) {
      // Move para o final (mais recente)
      this.cache.delete(key);
      this.cache.set(key, value);
    }
    return value;
  }

  set(key: K, value: V): void {
    if (this.cache.has(key)) {
      this.cache.delete(key);
    } else if (this.cache.size >= this.maxSize) {
      // Remove o mais antigo (primeiro da Map)
      const firstKey = this.cache.keys().next().value;
      this.cache.delete(firstKey);
    }
    this.cache.set(key, value);
  }

  clear(): void {
    this.cache.clear();
  }

  size(): number {
    return this.cache.size;
  }
}

// Debounce otimizado
export function debounce<T extends (...args: any[]) => any>(
  func: T,
  wait: number,
  immediate?: boolean
): (...args: Parameters<T>) => void {
  let timeout: NodeJS.Timeout | null = null;
  
  return function executedFunction(...args: Parameters<T>) {
    const later = () => {
      timeout = null;
      if (!immediate) func(...args);
    };
    
    const callNow = immediate && !timeout;
    
    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    
    if (callNow) func(...args);
  };
}

// Throttle otimizado
export function throttle<T extends (...args: any[]) => any>(
  func: T,
  limit: number
): (...args: Parameters<T>) => void {
  let inThrottle: boolean = false;
  
  return function executedFunction(...args: Parameters<T>) {
    if (!inThrottle) {
      func(...args);
      inThrottle = true;
      setTimeout(() => inThrottle = false, limit);
    }
  };
}

// Memoização otimizada
export function memoize<T extends (...args: any[]) => any>(
  fn: T,
  getKey?: (...args: Parameters<T>) => string
): T & { cache: LRUCache<string, ReturnType<T>>; clearCache: () => void } {
  const cache = new LRUCache<string, ReturnType<T>>(50);
  
  const memoized = function (...args: Parameters<T>): ReturnType<T> {
    const key = getKey ? getKey(...args) : JSON.stringify(args);
    
    const cached = cache.get(key);
    if (cached !== undefined) {
      return cached;
    }
    
    const result = fn(...args);
    cache.set(key, result);
    return result;
  } as T & { cache: LRUCache<string, ReturnType<T>>; clearCache: () => void };
  
  memoized.cache = cache;
  memoized.clearCache = () => cache.clear();
  
  return memoized;
}

// Worker Pool para cálculos pesados
export class WorkerPool {
  private workers: Worker[] = [];
  private queue: Array<{
    resolve: (value: any) => void;
    reject: (error: any) => void;
    data: any;
  }> = [];
  private busyWorkers = new Set<Worker>();

  constructor(workerScript: string, poolSize: number = navigator.hardwareConcurrency || 4) {
    for (let i = 0; i < poolSize; i++) {
      const worker = new Worker(workerScript);
      worker.onmessage = (e) => this.handleWorkerMessage(worker, e);
      worker.onerror = (e) => this.handleWorkerError(worker, e);
      this.workers.push(worker);
    }
  }

  execute<T>(data: any): Promise<T> {
    return new Promise((resolve, reject) => {
      this.queue.push({ resolve, reject, data });
      this.processQueue();
    });
  }

  private processQueue(): void {
    if (this.queue.length === 0) return;
    
    const availableWorker = this.workers.find(w => !this.busyWorkers.has(w));
    if (!availableWorker) return;
    
    const task = this.queue.shift()!;
    this.busyWorkers.add(availableWorker);
    
    (availableWorker as any)._currentTask = task;
    availableWorker.postMessage(task.data);
  }

  private handleWorkerMessage(worker: Worker, e: MessageEvent): void {
    const task = (worker as any)._currentTask;
    if (task) {
      task.resolve(e.data);
      this.busyWorkers.delete(worker);
      delete (worker as any)._currentTask;
      this.processQueue();
    }
  }

  private handleWorkerError(worker: Worker, e: ErrorEvent): void {
    const task = (worker as any)._currentTask;
    if (task) {
      task.reject(e);
      this.busyWorkers.delete(worker);
      delete (worker as any)._currentTask;
      this.processQueue();
    }
  }

  terminate(): void {
    this.workers.forEach(worker => worker.terminate());
    this.workers = [];
    this.queue = [];
    this.busyWorkers.clear();
  }
}

// Lazy loading de imagens otimizado
export class LazyImageLoader {
  private observer: IntersectionObserver;
  private images = new Set<HTMLImageElement>();

  constructor(rootMargin: string = '50px') {
    this.observer = new IntersectionObserver(
      (entries) => {
        entries.forEach(entry => {
          if (entry.isIntersecting) {
            const img = entry.target as HTMLImageElement;
            this.loadImage(img);
          }
        });
      },
      { rootMargin }
    );
  }

  observe(img: HTMLImageElement): void {
    this.images.add(img);
    this.observer.observe(img);
  }

  unobserve(img: HTMLImageElement): void {
    this.images.delete(img);
    this.observer.unobserve(img);
  }

  private loadImage(img: HTMLImageElement): void {
    const src = img.dataset.src;
    if (src) {
      img.src = src;
      img.onload = () => {
        img.classList.add('loaded');
        this.observer.unobserve(img);
      };
    }
  }

  disconnect(): void {
    this.observer.disconnect();
    this.images.clear();
  }
}

// Monitor de performance
export class PerformanceMonitor {
  private metrics = new Map<string, number[]>();
  private observers: PerformanceObserver[] = [];

  constructor() {
    this.setupObservers();
  }

  private setupObservers(): void {
    if ('PerformanceObserver' in window) {
      // Long tasks
      try {
        const longTaskObserver = new PerformanceObserver((list) => {
          for (const entry of list.getEntries()) {
            this.addMetric('long-task', entry.duration);
          }
        });
        longTaskObserver.observe({ entryTypes: ['longtask'] });
        this.observers.push(longTaskObserver);
      } catch (e) {
        // Long tasks não suportado
      }

      // Layout shifts
      try {
        const layoutShiftObserver = new PerformanceObserver((list) => {
          for (const entry of list.getEntries()) {
            if ((entry as any).value && !(entry as any).hadRecentInput) {
              this.addMetric('layout-shift', (entry as any).value);
            }
          }
        });
        layoutShiftObserver.observe({ entryTypes: ['layout-shift'] });
        this.observers.push(layoutShiftObserver);
      } catch (e) {
        // Layout shift não suportado
      }
    }
  }

  addMetric(name: string, value: number): void {
    if (!this.metrics.has(name)) {
      this.metrics.set(name, []);
    }
    this.metrics.get(name)!.push(value);
  }

  getMetrics(): Record<string, { avg: number; max: number; count: number }> {
    const result: Record<string, { avg: number; max: number; count: number }> = {};
    
    this.metrics.forEach((values, name) => {
      result[name] = {
        avg: values.reduce((a, b) => a + b, 0) / values.length,
        max: Math.max(...values),
        count: values.length
      };
    });
    
    return result;
  }

  clear(): void {
    this.metrics.clear();
  }

  disconnect(): void {
    this.observers.forEach(observer => observer.disconnect());
    this.observers = [];
  }
}

// Instâncias globais
export const performanceMonitor = new PerformanceMonitor();
export const imageLoader = new LazyImageLoader();

// Hook para uso em React
export function usePerformanceMetrics() {
  return {
    getMetrics: () => performanceMonitor.getMetrics(),
    addMetric: (name: string, value: number) => performanceMonitor.addMetric(name, value),
    clear: () => performanceMonitor.clear()
  };
}