/**
 * MemoryManager - Gestion intelligente de la mémoire
 * Surveille et optimise l'utilisation mémoire de l'application
 */
export interface MemoryStats {
  usedJSHeapSize: number;
  totalJSHeapSize: number;
  jsHeapSizeLimit: number;
  timestamp: number;
}

export interface CacheEntry<T> {
  data: T;
  timestamp: number;
  accessCount: number;
  lastAccessed: number;
}

export class MemoryManager {
  private static instance: MemoryManager;
  private caches: Map<string, Map<string, CacheEntry<any>>> = new Map();
  private maxCacheSize = 100;
  private maxCacheAge = 5 * 60 * 1000; // 5 minutes
  private cleanupInterval: number | null = null;
  private memoryThreshold = 100 * 1024 * 1024; // 100MB
  private isMonitoring = false;

  private constructor() {
    this.startCleanupInterval();
  }

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

  /**
   * Démarre le monitoring de la mémoire
   */
  startMonitoring(): void {
    if (this.isMonitoring) return;

    this.isMonitoring = true;
    this.logMemoryStats();

    // Vérifier la mémoire toutes les 2 minutes
    setInterval(() => {
      this.checkMemoryUsage();
    }, 120000);
  }

  /**
   * Arrête le monitoring de la mémoire
   */
  stopMonitoring(): void {
    this.isMonitoring = false;
    if (this.cleanupInterval) {
      clearInterval(this.cleanupInterval);
      this.cleanupInterval = null;
    }
  }

  /**
   * Met en cache une valeur avec gestion automatique
   */
  setCache<T>(cacheName: string, key: string, value: T): void {
    if (!this.caches.has(cacheName)) {
      this.caches.set(cacheName, new Map());
    }

    const cache = this.caches.get(cacheName)!;
    const now = Date.now();

    // Vérifier si le cache est plein
    if (cache.size >= this.maxCacheSize) {
      this.evictOldestEntry(cache);
    }

    cache.set(key, {
      data: value,
      timestamp: now,
      accessCount: 0,
      lastAccessed: now
    });
  }

  /**
   * Récupère une valeur du cache
   */
  getCache<T>(cacheName: string, key: string): T | null {
    const cache = this.caches.get(cacheName);
    if (!cache) return null;

    const entry = cache.get(key);
    if (!entry) return null;

    // Vérifier l'âge de l'entrée
    if (Date.now() - entry.timestamp > this.maxCacheAge) {
      cache.delete(key);
      return null;
    }

    // Mettre à jour les statistiques d'accès
    entry.accessCount++;
    entry.lastAccessed = Date.now();

    return entry.data;
  }

  /**
   * Supprime une entrée du cache
   */
  deleteCache(cacheName: string, key: string): boolean {
    const cache = this.caches.get(cacheName);
    if (!cache) return false;

    return cache.delete(key);
  }

  /**
   * Vide un cache complet
   */
  clearCache(cacheName: string): void {
    const cache = this.caches.get(cacheName);
    if (cache) {
      cache.clear();
    }
  }

  /**
   * Vide tous les caches
   */
  clearAllCaches(): void {
    this.caches.forEach(cache => cache.clear());
  }

  /**
   * Récupère les statistiques d'un cache
   */
  getCacheStats(cacheName: string): { size: number; entries: any[] } {
    const cache = this.caches.get(cacheName);
    if (!cache) return { size: 0, entries: [] };

    const entries = Array.from(cache.entries()).map(([key, entry]) => ({
      key,
      age: Date.now() - entry.timestamp,
      accessCount: entry.accessCount,
      lastAccessed: entry.lastAccessed
    }));

    return {
      size: cache.size,
      entries
    };
  }

  /**
   * Récupère les statistiques de mémoire
   */
  getMemoryStats(): MemoryStats | null {
    const memory = (performance as any).memory;
    if (!memory) return null;

    return {
      usedJSHeapSize: memory.usedJSHeapSize,
      totalJSHeapSize: memory.totalJSHeapSize,
      jsHeapSizeLimit: memory.jsHeapSizeLimit,
      timestamp: Date.now()
    };
  }

  /**
   * Vérifie l'utilisation mémoire et déclenche le nettoyage si nécessaire
   */
  private checkMemoryUsage(): void {
    const stats = this.getMemoryStats();
    if (!stats) return;

    if (stats.usedJSHeapSize > this.memoryThreshold) {
      this.performMemoryCleanup();
    }
  }

  /**
   * Effectue un nettoyage de mémoire
   */
  private performMemoryCleanup(): void {
    console.log('🧹 Performing memory cleanup...');

    // Nettoyer les caches expirés
    this.cleanupExpiredEntries();

    // Supprimer les entrées les moins utilisées
    this.evictLeastUsedEntries();

    // Forcer le garbage collection si disponible
    if (window.gc) {
      window.gc();
    }
  }

  /**
   * Nettoie les entrées expirées
   */
  private cleanupExpiredEntries(): void {
    const now = Date.now();

    this.caches.forEach(cache => {
      const keysToDelete: string[] = [];

      cache.forEach((entry, key) => {
        if (now - entry.timestamp > this.maxCacheAge) {
          keysToDelete.push(key);
        }
      });

      keysToDelete.forEach(key => cache.delete(key));
    });
  }

  /**
   * Supprime les entrées les moins utilisées
   */
  private evictLeastUsedEntries(): void {
    this.caches.forEach(cache => {
      if (cache.size <= this.maxCacheSize) return;

      // Trier par nombre d'accès et dernière utilisation
      const entries = Array.from(cache.entries()).sort((a, b) => {
        const scoreA = a[1].accessCount + (Date.now() - a[1].lastAccessed) / 1000;
        const scoreB = b[1].accessCount + (Date.now() - b[1].lastAccessed) / 1000;
        return scoreA - scoreB;
      });

      // Supprimer les 20% les moins utilisés
      const toDelete = Math.ceil(entries.length * 0.2);
      for (let i = 0; i < toDelete; i++) {
        cache.delete(entries[i][0]);
      }
    });
  }

  /**
   * Supprime l'entrée la plus ancienne d'un cache
   */
  private evictOldestEntry(cache: Map<string, CacheEntry<any>>): void {
    let oldestKey = '';
    let oldestTime = Date.now();

    cache.forEach((entry, key) => {
      if (entry.timestamp < oldestTime) {
        oldestTime = entry.timestamp;
        oldestKey = key;
      }
    });

    if (oldestKey) {
      cache.delete(oldestKey);
    }
  }

  /**
   * Démarre l'intervalle de nettoyage automatique
   */
  private startCleanupInterval(): void {
    this.cleanupInterval = setInterval(() => {
      this.cleanupExpiredEntries();
    }, 60000) as any; // Nettoyage toutes les minutes
  }

  /**
   * Log les statistiques de mémoire
   */
  private logMemoryStats(): void {
    const stats = this.getMemoryStats();
    if (stats) {
      console.log('📊 Memory Stats:', {
        used: `${Math.round(stats.usedJSHeapSize / 1024 / 1024)}MB`,
        total: `${Math.round(stats.totalJSHeapSize / 1024 / 1024)}MB`,
        limit: `${Math.round(stats.jsHeapSizeLimit / 1024 / 1024)}MB`,
        usage: `${Math.round((stats.usedJSHeapSize / stats.jsHeapSizeLimit) * 100)}%`
      });
    }
  }

  /**
   * Récupère un rapport complet de la mémoire
   */
  getMemoryReport(): {
    memory: MemoryStats | null;
    caches: Record<string, { size: number; entries: any[] }>;
    recommendations: string[];
  } {
    const memory = this.getMemoryStats();
    const caches: Record<string, { size: number; entries: any[] }> = {};

    this.caches.forEach((cache, name) => {
      // Use cache variable
      console.log('Cache:', cache);
      caches[name] = this.getCacheStats(name);
    });

    const recommendations: string[] = [];

    if (memory) {
      const usagePercent = (memory.usedJSHeapSize / memory.jsHeapSizeLimit) * 100;

      if (usagePercent > 80) {
        recommendations.push('High memory usage detected. Consider clearing caches.');
      }

      if (usagePercent > 90) {
        recommendations.push('Critical memory usage. Immediate cleanup recommended.');
      }
    }

    const totalCacheEntries = Object.values(caches).reduce((sum, cache) => sum + cache.size, 0);
    if (totalCacheEntries > 500) {
      recommendations.push('Large number of cache entries. Consider reducing cache size.');
    }

    return {
      memory,
      caches,
      recommendations
    };
  }
}

// Instance singleton pour l'application
export const memoryManager = MemoryManager.getInstance();