import * as plugins from '../../plugins.js';
import type { SmartProxy } from './smart-proxy.js';
import type { 
  IMetrics, 
  IThroughputData, 
  IThroughputHistoryPoint,
  IByteTracker 
} from './models/metrics-types.js';
import { ThroughputTracker } from './throughput-tracker.js';
import { logger } from '../../core/utils/logger.js';

/**
 * Collects and provides metrics for SmartProxy with clean API
 */
export class MetricsCollector implements IMetrics {
  // Throughput tracking
  private throughputTracker: ThroughputTracker;
  
  // Request tracking
  private requestTimestamps: number[] = [];
  private totalRequests: number = 0;
  
  // Connection byte tracking for per-route/IP metrics
  private connectionByteTrackers = new Map<string, IByteTracker>();
  
  // Subscriptions
  private samplingInterval?: NodeJS.Timeout;
  private connectionSubscription?: plugins.smartrx.rxjs.Subscription;
  
  // Configuration
  private readonly sampleIntervalMs: number;
  private readonly retentionSeconds: number;
  
  constructor(
    private smartProxy: SmartProxy,
    config?: {
      sampleIntervalMs?: number;
      retentionSeconds?: number;
    }
  ) {
    this.sampleIntervalMs = config?.sampleIntervalMs || 1000;
    this.retentionSeconds = config?.retentionSeconds || 3600;
    this.throughputTracker = new ThroughputTracker(this.retentionSeconds);
  }
  
  // Connection metrics implementation
  public connections = {
    active: (): number => {
      return this.smartProxy.connectionManager.getConnectionCount();
    },
    
    total: (): number => {
      const stats = this.smartProxy.connectionManager.getTerminationStats();
      let total = this.smartProxy.connectionManager.getConnectionCount();
      
      for (const reason in stats.incoming) {
        total += stats.incoming[reason];
      }
      
      return total;
    },
    
    byRoute: (): Map<string, number> => {
      const routeCounts = new Map<string, number>();
      const connections = this.smartProxy.connectionManager.getConnections();
      
      for (const [_, record] of connections) {
        const routeName = (record as any).routeName || 
                         record.routeConfig?.name || 
                         'unknown';
        
        const current = routeCounts.get(routeName) || 0;
        routeCounts.set(routeName, current + 1);
      }
      
      return routeCounts;
    },
    
    byIP: (): Map<string, number> => {
      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);
      }
      
      return ipCounts;
    },
    
    topIPs: (limit: number = 10): Array<{ ip: string; count: number }> => {
      const ipCounts = this.connections.byIP();
      return Array.from(ipCounts.entries())
        .sort((a, b) => b[1] - a[1])
        .slice(0, limit)
        .map(([ip, count]) => ({ ip, count }));
    }
  };
  
  // Throughput metrics implementation
  public throughput = {
    instant: (): IThroughputData => {
      return this.throughputTracker.getRate(1);
    },
    
    recent: (): IThroughputData => {
      return this.throughputTracker.getRate(10);
    },
    
    average: (): IThroughputData => {
      return this.throughputTracker.getRate(60);
    },
    
    custom: (seconds: number): IThroughputData => {
      return this.throughputTracker.getRate(seconds);
    },
    
    history: (seconds: number): Array<IThroughputHistoryPoint> => {
      return this.throughputTracker.getHistory(seconds);
    },
    
    byRoute: (windowSeconds: number = 60): Map<string, IThroughputData> => {
      const routeThroughput = new Map<string, IThroughputData>();
      const now = Date.now();
      const windowStart = now - (windowSeconds * 1000);
      
      // Aggregate bytes by route - calculate actual bytes transferred in window
      const routeData = new Map<string, { bytesIn: number; bytesOut: number }>();
      
      for (const [_, tracker] of this.connectionByteTrackers) {
        // Only include connections that were active within the window
        if (tracker.lastUpdate > windowStart) {
          let windowBytesIn = 0;
          let windowBytesOut = 0;
          
          if (tracker.windowSnapshots && tracker.windowSnapshots.length > 0) {
            // Find the earliest snapshot within or just before the window
            let startSnapshot = { timestamp: tracker.startTime, bytesIn: 0, bytesOut: 0 };
            for (const snapshot of tracker.windowSnapshots) {
              if (snapshot.timestamp <= windowStart) {
                startSnapshot = snapshot;
              } else {
                break;
              }
            }
            
            // Calculate bytes transferred since window start
            windowBytesIn = tracker.bytesIn - startSnapshot.bytesIn;
            windowBytesOut = tracker.bytesOut - startSnapshot.bytesOut;
          } else if (tracker.startTime > windowStart) {
            // Connection started within window, use all its bytes
            windowBytesIn = tracker.bytesIn;
            windowBytesOut = tracker.bytesOut;
          }
          
          // Add to route totals
          const current = routeData.get(tracker.routeName) || { bytesIn: 0, bytesOut: 0 };
          current.bytesIn += windowBytesIn;
          current.bytesOut += windowBytesOut;
          routeData.set(tracker.routeName, current);
        }
      }
      
      // Convert to rates (bytes per second)
      for (const [route, data] of routeData) {
        routeThroughput.set(route, {
          in: Math.round(data.bytesIn / windowSeconds),
          out: Math.round(data.bytesOut / windowSeconds)
        });
      }
      
      return routeThroughput;
    },
    
    byIP: (windowSeconds: number = 60): Map<string, IThroughputData> => {
      const ipThroughput = new Map<string, IThroughputData>();
      const now = Date.now();
      const windowStart = now - (windowSeconds * 1000);
      
      // Aggregate bytes by IP - calculate actual bytes transferred in window
      const ipData = new Map<string, { bytesIn: number; bytesOut: number }>();
      
      for (const [_, tracker] of this.connectionByteTrackers) {
        // Only include connections that were active within the window
        if (tracker.lastUpdate > windowStart) {
          let windowBytesIn = 0;
          let windowBytesOut = 0;
          
          if (tracker.windowSnapshots && tracker.windowSnapshots.length > 0) {
            // Find the earliest snapshot within or just before the window
            let startSnapshot = { timestamp: tracker.startTime, bytesIn: 0, bytesOut: 0 };
            for (const snapshot of tracker.windowSnapshots) {
              if (snapshot.timestamp <= windowStart) {
                startSnapshot = snapshot;
              } else {
                break;
              }
            }
            
            // Calculate bytes transferred since window start
            windowBytesIn = tracker.bytesIn - startSnapshot.bytesIn;
            windowBytesOut = tracker.bytesOut - startSnapshot.bytesOut;
          } else if (tracker.startTime > windowStart) {
            // Connection started within window, use all its bytes
            windowBytesIn = tracker.bytesIn;
            windowBytesOut = tracker.bytesOut;
          }
          
          // Add to IP totals
          const current = ipData.get(tracker.remoteIP) || { bytesIn: 0, bytesOut: 0 };
          current.bytesIn += windowBytesIn;
          current.bytesOut += windowBytesOut;
          ipData.set(tracker.remoteIP, current);
        }
      }
      
      // Convert to rates (bytes per second)
      for (const [ip, data] of ipData) {
        ipThroughput.set(ip, {
          in: Math.round(data.bytesIn / windowSeconds),
          out: Math.round(data.bytesOut / windowSeconds)
        });
      }
      
      return ipThroughput;
    }
  };
  
  // Request metrics implementation
  public requests = {
    perSecond: (): number => {
      const now = Date.now();
      const oneSecondAgo = now - 1000;
      
      // Clean old timestamps
      this.requestTimestamps = this.requestTimestamps.filter(ts => ts > now - 60000);
      
      // Count requests in last second
      const recentRequests = this.requestTimestamps.filter(ts => ts > oneSecondAgo);
      return recentRequests.length;
    },
    
    perMinute: (): number => {
      const now = Date.now();
      const oneMinuteAgo = now - 60000;
      
      // Count requests in last minute
      const recentRequests = this.requestTimestamps.filter(ts => ts > oneMinuteAgo);
      return recentRequests.length;
    },
    
    total: (): number => {
      return this.totalRequests;
    }
  };
  
  // Totals implementation
  public totals = {
    bytesIn: (): number => {
      let total = 0;
      
      // Sum from all active connections
      for (const [_, record] of this.smartProxy.connectionManager.getConnections()) {
        total += record.bytesReceived;
      }
      
      // TODO: Add historical data from terminated connections
      
      return total;
    },
    
    bytesOut: (): number => {
      let total = 0;
      
      // Sum from all active connections
      for (const [_, record] of this.smartProxy.connectionManager.getConnections()) {
        total += record.bytesSent;
      }
      
      // TODO: Add historical data from terminated connections
      
      return total;
    },
    
    connections: (): number => {
      return this.connections.total();
    }
  };
  
  // Percentiles implementation (placeholder for now)
  public percentiles = {
    connectionDuration: (): { p50: number; p95: number; p99: number } => {
      // TODO: Implement percentile calculations
      return { p50: 0, p95: 0, p99: 0 };
    },
    
    bytesTransferred: (): { 
      in: { p50: number; p95: number; p99: number };
      out: { p50: number; p95: number; p99: number };
    } => {
      // TODO: Implement percentile calculations
      return {
        in: { p50: 0, p95: 0, p99: 0 },
        out: { p50: 0, p95: 0, p99: 0 }
      };
    }
  };
  
  /**
   * Record a new request
   */
  public recordRequest(connectionId: string, routeName: string, remoteIP: string): void {
    const now = Date.now();
    this.requestTimestamps.push(now);
    this.totalRequests++;
    
    // Initialize byte tracker for this connection
    this.connectionByteTrackers.set(connectionId, {
      connectionId,
      routeName,
      remoteIP,
      bytesIn: 0,
      bytesOut: 0,
      startTime: now,
      lastUpdate: now,
      windowSnapshots: []  // Initialize empty snapshots array
    });
    
    // Cleanup old request timestamps
    if (this.requestTimestamps.length > 5000) {
      // First try to clean up old timestamps (older than 1 minute)
      const cutoff = now - 60000;
      this.requestTimestamps = this.requestTimestamps.filter(ts => ts > cutoff);
      
      // If still too many, enforce hard cap of 5000 most recent
      if (this.requestTimestamps.length > 5000) {
        this.requestTimestamps = this.requestTimestamps.slice(-5000);
      }
    }
  }
  
  /**
   * Record bytes transferred for a connection
   */
  public recordBytes(connectionId: string, bytesIn: number, bytesOut: number): void {
    // Update global throughput tracker
    this.throughputTracker.recordBytes(bytesIn, bytesOut);
    
    // Update connection-specific tracker
    const tracker = this.connectionByteTrackers.get(connectionId);
    if (tracker) {
      tracker.bytesIn += bytesIn;
      tracker.bytesOut += bytesOut;
      tracker.lastUpdate = Date.now();
      
      // Initialize snapshots array if not present
      if (!tracker.windowSnapshots) {
        tracker.windowSnapshots = [];
      }
      
      // Add current snapshot - we'll use these for accurate windowed calculations
      tracker.windowSnapshots.push({
        timestamp: Date.now(),
        bytesIn: tracker.bytesIn,
        bytesOut: tracker.bytesOut
      });
      
      // Keep only snapshots from last 5 minutes to prevent memory growth
      const fiveMinutesAgo = Date.now() - 300000;
      tracker.windowSnapshots = tracker.windowSnapshots.filter(s => s.timestamp > fiveMinutesAgo);
    }
  }
  
  /**
   * Clean up tracking for a closed connection
   */
  public removeConnection(connectionId: string): void {
    this.connectionByteTrackers.delete(connectionId);
  }
  
  /**
   * Start the metrics collector
   */
  public start(): void {
    if (!this.smartProxy.routeConnectionHandler) {
      throw new Error('MetricsCollector: RouteConnectionHandler not available');
    }
    
    // Start periodic sampling
    this.samplingInterval = setInterval(() => {
      this.throughputTracker.takeSample();
      
      // Clean up old connection trackers (connections closed more than 5 minutes ago)
      const cutoff = Date.now() - 300000;
      for (const [id, tracker] of this.connectionByteTrackers) {
        if (tracker.lastUpdate < cutoff) {
          this.connectionByteTrackers.delete(id);
        }
      }
    }, this.sampleIntervalMs);
    
    // Subscribe to new connections
    this.connectionSubscription = this.smartProxy.routeConnectionHandler.newConnectionSubject.subscribe({
      next: (record) => {
        const routeName = record.routeConfig?.name || 'unknown';
        this.recordRequest(record.id, routeName, record.remoteIP);
        
        if (this.smartProxy.settings?.enableDetailedLogging) {
          logger.log('debug', `MetricsCollector: New connection recorded`, {
            connectionId: record.id,
            remoteIP: record.remoteIP,
            routeName,
            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
   */
  public stop(): void {
    if (this.samplingInterval) {
      clearInterval(this.samplingInterval);
      this.samplingInterval = undefined;
    }
    
    if (this.connectionSubscription) {
      this.connectionSubscription.unsubscribe();
      this.connectionSubscription = undefined;
    }
    
    logger.log('debug', 'MetricsCollector stopped', { component: 'metrics' });
  }
  
  /**
   * Alias for stop() for compatibility
   */
  public destroy(): void {
    this.stop();
  }
}