import * as plugins from '../../plugins.js';
import type { SmartProxy } from './smart-proxy.js';
import type { IProxyStats, IProxyStatsExtended } from './models/metrics-types.js';
import { logger } from '../../core/utils/logger.js';

/**
 * Collects and computes metrics for SmartProxy on-demand
 */
export class MetricsCollector implements IProxyStatsExtended {
  // RPS tracking (the only state we need to maintain)
  private requestTimestamps: number[] = [];
  private readonly RPS_WINDOW_SIZE = 60000; // 1 minute window
  private readonly MAX_TIMESTAMPS = 5000; // Maximum timestamps to keep
  
  // Optional caching for performance
  private cachedMetrics: {
    timestamp: number;
    connectionsByRoute?: Map<string, number>;
    connectionsByIP?: Map<string, number>;
  } = { timestamp: 0 };
  
  private readonly CACHE_TTL = 1000; // 1 second cache
  
  // RxJS subscription for connection events
  private connectionSubscription?: plugins.smartrx.rxjs.Subscription;
  
  constructor(
    private smartProxy: SmartProxy
  ) {
    // Subscription will be set up in start() method
  }
  
  /**
   * Get the current number of active connections
   */
  public getActiveConnections(): number {
    return this.smartProxy.connectionManager.getConnectionCount();
  }
  
  /**
   * Get connection counts grouped by route name
   */
  public getConnectionsByRoute(): Map<string, number> {
    const now = Date.now();
    
    // Return cached value if fresh
    if (this.cachedMetrics.connectionsByRoute && 
        now - this.cachedMetrics.timestamp < this.CACHE_TTL) {
      return new Map(this.cachedMetrics.connectionsByRoute);
    }
    
    // Compute fresh value
    const routeCounts = new Map<string, number>();
    const connections = this.smartProxy.connectionManager.getConnections();
    
    if (this.smartProxy.settings?.enableDetailedLogging) {
      logger.log('debug', `MetricsCollector: Computing route connections`, {
        totalConnections: connections.size,
        component: 'metrics'
      });
    }
    
    for (const [_, record] of connections) {
      // Try different ways to get the route name
      const routeName = (record as any).routeName || 
                       record.routeConfig?.name || 
                       (record.routeConfig as any)?.routeName ||
                       'unknown';
      
      if (this.smartProxy.settings?.enableDetailedLogging) {
        logger.log('debug', `MetricsCollector: Connection route info`, {
          connectionId: record.id,
          routeName,
          hasRouteConfig: !!record.routeConfig,
          routeConfigName: record.routeConfig?.name,
          routeConfigKeys: record.routeConfig ? Object.keys(record.routeConfig) : [],
          component: 'metrics'
        });
      }
      
      const current = routeCounts.get(routeName) || 0;
      routeCounts.set(routeName, current + 1);
    }
    
    // Cache and return
    this.cachedMetrics.connectionsByRoute = routeCounts;
    this.cachedMetrics.timestamp = now;
    return new Map(routeCounts);
  }
  
  /**
   * Get connection counts grouped by IP address
   */
  public getConnectionsByIP(): Map<string, number> {
    const now = Date.now();
    
    // Return cached value if fresh
    if (this.cachedMetrics.connectionsByIP && 
        now - this.cachedMetrics.timestamp < this.CACHE_TTL) {
      return new Map(this.cachedMetrics.connectionsByIP);
    }
    
    // Compute fresh value
    const ipCounts = new Map<string, number>();
    for (const [_, record] of this.smartProxy.connectionManager.getConnections()) {
      const ip = record.remoteIP;
      const current = ipCounts.get(ip) || 0;
      ipCounts.set(ip, current + 1);
    }
    
    // Cache and return
    this.cachedMetrics.connectionsByIP = ipCounts;
    this.cachedMetrics.timestamp = now;
    return new Map(ipCounts);
  }
  
  /**
   * Get the total number of connections since proxy start
   */
  public getTotalConnections(): number {
    // Get from termination stats
    const stats = this.smartProxy.connectionManager.getTerminationStats();
    let total = this.smartProxy.connectionManager.getConnectionCount(); // Add active connections
    
    // Add all terminated connections
    for (const reason in stats.incoming) {
      total += stats.incoming[reason];
    }
    
    return total;
  }
  
  /**
   * Get the current requests per second rate
   */
  public getRequestsPerSecond(): number {
    const now = Date.now();
    const windowStart = now - this.RPS_WINDOW_SIZE;
    
    // Clean old timestamps
    this.requestTimestamps = this.requestTimestamps.filter(ts => ts > windowStart);
    
    // Calculate RPS based on window
    const requestsInWindow = this.requestTimestamps.length;
    return requestsInWindow / (this.RPS_WINDOW_SIZE / 1000);
  }
  
  /**
   * Record a new request for RPS tracking
   */
  public recordRequest(): void {
    const now = Date.now();
    this.requestTimestamps.push(now);
    
    // Prevent unbounded growth - clean up more aggressively
    if (this.requestTimestamps.length > this.MAX_TIMESTAMPS) {
      // Keep only timestamps within the window
      const cutoff = now - this.RPS_WINDOW_SIZE;
      this.requestTimestamps = this.requestTimestamps.filter(ts => ts > cutoff);
    }
  }
  
  /**
   * Get total throughput (bytes transferred)
   */
  public getThroughput(): { bytesIn: number; bytesOut: number } {
    let bytesIn = 0;
    let bytesOut = 0;
    
    // Sum bytes from all active connections
    for (const [_, record] of this.smartProxy.connectionManager.getConnections()) {
      bytesIn += record.bytesReceived;
      bytesOut += record.bytesSent;
    }
    
    return { bytesIn, bytesOut };
  }
  
  /**
   * Get throughput rate (bytes per second) for last minute
   */
  public getThroughputRate(): { bytesInPerSec: number; bytesOutPerSec: number } {
    const now = Date.now();
    let recentBytesIn = 0;
    let recentBytesOut = 0;
    
    // Calculate bytes transferred in last minute from active connections
    for (const [_, record] of this.smartProxy.connectionManager.getConnections()) {
      const connectionAge = now - record.incomingStartTime;
      if (connectionAge < 60000) { // Connection started within last minute
        recentBytesIn += record.bytesReceived;
        recentBytesOut += record.bytesSent;
      } else {
        // For older connections, estimate rate based on average
        const rate = connectionAge / 60000;
        recentBytesIn += record.bytesReceived / rate;
        recentBytesOut += record.bytesSent / rate;
      }
    }
    
    return {
      bytesInPerSec: Math.round(recentBytesIn / 60),
      bytesOutPerSec: Math.round(recentBytesOut / 60)
    };
  }
  
  /**
   * Get top IPs by connection count
   */
  public getTopIPs(limit: number = 10): Array<{ ip: string; connections: number }> {
    const ipCounts = this.getConnectionsByIP();
    const sorted = Array.from(ipCounts.entries())
      .sort((a, b) => b[1] - a[1])
      .slice(0, limit)
      .map(([ip, connections]) => ({ ip, connections }));
    
    return sorted;
  }
  
  /**
   * Check if an IP has reached the connection limit
   */
  public isIPBlocked(ip: string, maxConnectionsPerIP: number): boolean {
    const ipCounts = this.getConnectionsByIP();
    const currentConnections = ipCounts.get(ip) || 0;
    return currentConnections >= maxConnectionsPerIP;
  }
  
  /**
   * Clean up old request timestamps
   */
  private cleanupOldRequests(): void {
    const cutoff = Date.now() - this.RPS_WINDOW_SIZE;
    this.requestTimestamps = this.requestTimestamps.filter(ts => ts > cutoff);
  }
  
  /**
   * Start the metrics collector and set up subscriptions
   */
  public start(): void {
    if (!this.smartProxy.routeConnectionHandler) {
      throw new Error('MetricsCollector: RouteConnectionHandler not available');
    }
    
    // Subscribe to the newConnectionSubject from RouteConnectionHandler
    this.connectionSubscription = this.smartProxy.routeConnectionHandler.newConnectionSubject.subscribe({
      next: (record) => {
        this.recordRequest();
        
        // Optional: Log connection details
        if (this.smartProxy.settings?.enableDetailedLogging) {
          logger.log('debug', `MetricsCollector: New connection recorded`, {
            connectionId: record.id,
            remoteIP: record.remoteIP,
            routeName: record.routeConfig?.name || 'unknown',
            component: 'metrics'
          });
        }
      },
      error: (err) => {
        logger.log('error', `MetricsCollector: Error in connection subscription`, {
          error: err.message,
          component: 'metrics'
        });
      }
    });
    
    logger.log('debug', 'MetricsCollector started', { component: 'metrics' });
  }
  
  /**
   * Stop the metrics collector and clean up resources
   */
  public stop(): void {
    if (this.connectionSubscription) {
      this.connectionSubscription.unsubscribe();
      this.connectionSubscription = undefined;
    }
    
    logger.log('debug', 'MetricsCollector stopped', { component: 'metrics' });
  }
  
  /**
   * Alias for stop() for backward compatibility
   */
  public destroy(): void {
    this.stop();
  }
}