/**
 * Fallback API Client with Hierarchical Retry System
 * سیستم fallback سلسله مراتبی با 10 پشتیبان
 */

class FallbackAPIClient {
  constructor() {
    // لیست 10 endpoint پشتیبان به ترتیب اولویت
    this.endpoints = [
      'https://Really-amin-crypto-api-clean.hf.space',
      'https://really-amin-datasourceforcryptocurrency-2.hf.space',
      'https://really-amin-datasourceforcryptocurrency.hf.space',
      'http://localhost:7860',
      'http://localhost:8000',
      'https://api.coingecko.com/api/v3',
      'https://api.coincap.io/v2',
      'https://api.binance.com/api/v3',
      'https://api.kraken.com/0/public',
      'https://api.coinbase.com/v2'
    ];

    // Cache برای نتایج موفق
    this.cache = new Map();
    this.cacheTimeout = 60000; // 1 دقیقه

    // آمار برای monitoring
    this.stats = {
      totalRequests: 0,
      successfulRequests: 0,
      failedRequests: 0,
      endpointStats: {},
      lastSuccessfulEndpoint: null
    };

    // Initialize endpoint stats
    this.endpoints.forEach(endpoint => {
      this.stats.endpointStats[endpoint] = {
        requests: 0,
        successes: 0,
        failures: 0,
        avgResponseTime: 0,
        lastUsed: null
      };
    });
  }

  /**
   * درخواست با fallback سلسله مراتبی
   */
  async request(path, options = {}) {
    const {
      method = 'GET',
      body = null,
      headers = {},
      timeout = 10000,
      retryCount = 3,
      useCache = true
    } = options;

    // بررسی cache
    const cacheKey = `${method}:${path}:${JSON.stringify(body)}`;
    if (useCache && method === 'GET') {
      const cached = this.getFromCache(cacheKey);
      if (cached) {
        console.log('✅ Cache hit:', path);
        return cached;
      }
    }

    this.stats.totalRequests++;
    const errors = [];

    // تلاش با هر endpoint به ترتیب
    for (let i = 0; i < this.endpoints.length; i++) {
      const endpoint = this.endpoints[i];
      const endpointStats = this.stats.endpointStats[endpoint];

      try {
        console.log(`🔄 Trying endpoint ${i + 1}/${this.endpoints.length}: ${endpoint}`);
        
        const startTime = Date.now();
        const result = await this.makeRequest(endpoint, path, {
          method,
          body,
          headers,
          timeout
        });
        const responseTime = Date.now() - startTime;

        // به‌روزرسانی آمار موفق
        endpointStats.requests++;
        endpointStats.successes++;
        endpointStats.lastUsed = new Date().toISOString();
        endpointStats.avgResponseTime = 
          (endpointStats.avgResponseTime * (endpointStats.successes - 1) + responseTime) / 
          endpointStats.successes;

        this.stats.successfulRequests++;
        this.stats.lastSuccessfulEndpoint = endpoint;

        // ذخیره در cache
        if (useCache && method === 'GET') {
          this.saveToCache(cacheKey, result);
        }

        console.log(`✅ Success with endpoint ${i + 1}: ${endpoint} (${responseTime}ms)`);
        return result;

      } catch (error) {
        // به‌روزرسانی آمار خطا
        endpointStats.requests++;
        endpointStats.failures++;
        
        errors.push({
          endpoint,
          error: error.message,
          index: i + 1
        });

        console.warn(`❌ Failed endpoint ${i + 1}/${this.endpoints.length}: ${endpoint}`, error.message);

        // اگر آخرین endpoint بود، خطا بده
        if (i === this.endpoints.length - 1) {
          this.stats.failedRequests++;
          throw new Error(
            `All ${this.endpoints.length} endpoints failed:\n` +
            errors.map(e => `${e.index}. ${e.endpoint}: ${e.error}`).join('\n')
          );
        }

        // صبر کوتاه قبل از تلاش بعدی
        await this.sleep(500);
      }
    }
  }

  /**
   * ساخت درخواست به یک endpoint
   */
  async makeRequest(baseUrl, path, options) {
    const { method, body, headers, timeout } = options;

    // ساخت URL کامل
    const url = this.buildUrl(baseUrl, path);

    // ساخت AbortController برای timeout
    const controller = new AbortController();
    const timeoutId = setTimeout(() => controller.abort(), timeout);

    try {
      const response = await fetch(url, {
        method,
        headers: {
          'Content-Type': 'application/json',
          ...headers
        },
        body: body ? JSON.stringify(body) : null,
        signal: controller.signal
      });

      clearTimeout(timeoutId);

      if (!response.ok) {
        throw new Error(`HTTP ${response.status}: ${response.statusText}`);
      }

      const data = await response.json();
      return data;

    } catch (error) {
      clearTimeout(timeoutId);
      
      if (error.name === 'AbortError') {
        throw new Error(`Timeout after ${timeout}ms`);
      }
      
      throw error;
    }
  }

  /**
   * ساخت URL کامل
   */
  buildUrl(baseUrl, path) {
    // حذف slash اضافی
    baseUrl = baseUrl.replace(/\/$/, '');
    path = path.replace(/^\//, '');

    // تطبیق path با endpoint های مختلف
    if (baseUrl.includes('coingecko')) {
      return this.adaptToCoinGecko(baseUrl, path);
    } else if (baseUrl.includes('coincap')) {
      return this.adaptToCoinCap(baseUrl, path);
    } else if (baseUrl.includes('binance')) {
      return this.adaptToBinance(baseUrl, path);
    }

    // پیش‌فرض
    return `${baseUrl}/${path}`;
  }

  /**
   * تطبیق با CoinGecko API
   */
  adaptToCoinGecko(baseUrl, path) {
    if (path.includes('/api/coins/top')) {
      return `${baseUrl}/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=50`;
    }
    if (path.includes('/api/trending')) {
      return `${baseUrl}/search/trending`;
    }
    if (path.includes('/api/market')) {
      return `${baseUrl}/global`;
    }
    return `${baseUrl}/${path}`;
  }

  /**
   * تطبیق با CoinCap API
   */
  adaptToCoinCap(baseUrl, path) {
    if (path.includes('/api/coins/top')) {
      return `${baseUrl}/assets?limit=50`;
    }
    return `${baseUrl}/${path}`;
  }

  /**
   * تطبیق با Binance API
   */
  adaptToBinance(baseUrl, path) {
    if (path.includes('/api/coins/top')) {
      return `${baseUrl}/ticker/24hr`;
    }
    return `${baseUrl}/${path}`;
  }

  /**
   * Cache management
   */
  getFromCache(key) {
    const cached = this.cache.get(key);
    if (!cached) return null;

    const now = Date.now();
    if (now - cached.timestamp > this.cacheTimeout) {
      this.cache.delete(key);
      return null;
    }

    return cached.data;
  }

  saveToCache(key, data) {
    this.cache.set(key, {
      data,
      timestamp: Date.now()
    });

    // پاکسازی cache قدیمی
    if (this.cache.size > 100) {
      const oldestKey = this.cache.keys().next().value;
      this.cache.delete(oldestKey);
    }
  }

  /**
   * Helper: sleep
   */
  sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
  }

  /**
   * دریافت آمار
   */
  getStats() {
    return {
      ...this.stats,
      successRate: this.stats.totalRequests > 0 
        ? (this.stats.successfulRequests / this.stats.totalRequests * 100).toFixed(2) + '%'
        : '0%',
      cacheSize: this.cache.size
    };
  }

  /**
   * ریست آمار
   */
  resetStats() {
    this.stats.totalRequests = 0;
    this.stats.successfulRequests = 0;
    this.stats.failedRequests = 0;
    
    this.endpoints.forEach(endpoint => {
      this.stats.endpointStats[endpoint] = {
        requests: 0,
        successes: 0,
        failures: 0,
        avgResponseTime: 0,
        lastUsed: null
      };
    });
  }

  /**
   * پاکسازی cache
   */
  clearCache() {
    this.cache.clear();
  }

  /**
   * تغییر ترتیب endpoints بر اساس عملکرد
   */
  optimizeEndpoints() {
    // مرتب‌سازی بر اساس نرخ موفقیت و سرعت
    this.endpoints.sort((a, b) => {
      const statsA = this.stats.endpointStats[a];
      const statsB = this.stats.endpointStats[b];

      const successRateA = statsA.requests > 0 ? statsA.successes / statsA.requests : 0;
      const successRateB = statsB.requests > 0 ? statsB.successes / statsB.requests : 0;

      if (successRateA !== successRateB) {
        return successRateB - successRateA; // بیشترین موفقیت اول
      }

      return statsA.avgResponseTime - statsB.avgResponseTime; // سریع‌تر اول
    });

    console.log('✅ Endpoints optimized based on performance');
  }
}

// ============================================================================
// API Methods با Fallback
// ============================================================================

class CryptoAPI {
  constructor() {
    this.client = new FallbackAPIClient();
  }

  // Health & Status
  async health() {
    return this.client.request('/api/health');
  }

  async status() {
    return this.client.request('/api/status');
  }

  // Market Data
  async getTopCoins(limit = 50) {
    return this.client.request(`/api/coins/top?limit=${limit}`);
  }

  async getTrending() {
    return this.client.request('/api/trending');
  }

  async getMarket() {
    return this.client.request('/api/market');
  }

  // Sentiment
  async getGlobalSentiment(timeframe = '1D') {
    return this.client.request(`/api/sentiment/global?timeframe=${timeframe}`);
  }

  async getAssetSentiment(symbol) {
    return this.client.request(`/api/sentiment/asset/${symbol}`);
  }

  // News
  async getNews(limit = 50) {
    return this.client.request(`/api/news?limit=${limit}`);
  }

  // Resources
  async getResources() {
    return this.client.request('/api/resources/summary');
  }

  async getCategories() {
    return this.client.request('/api/categories');
  }

  // Models
  async getModels() {
    return this.client.request('/api/models/list');
  }

  // Stats
  getStats() {
    return this.client.getStats();
  }

  optimizeEndpoints() {
    this.client.optimizeEndpoints();
  }
}

// Export
if (typeof module !== 'undefined' && module.exports) {
  module.exports = { FallbackAPIClient, CryptoAPI };
}