// websocket.service.ts
// Path: /flare-ui/src/app/services/websocket.service.ts

import { Injectable } from '@angular/core';
import { Subject, Observable, timer, throwError } from 'rxjs';
import { retry, tap, catchError } from 'rxjs/operators';

export interface WebSocketMessage {
  type: string;
  [key: string]: any;
}

export interface TranscriptionResult {
  text: string;
  is_final: boolean;
  confidence: number;
}

export interface StateChangeMessage {
  from: string;
  to: string;
}

@Injectable({
  providedIn: 'root'
})
export class WebSocketService {
  private socket: WebSocket | null = null;
  private url: string = '';
  private reconnectAttempts = 0;
  private maxReconnectAttempts = 5;
  private reconnectDelay = 1000;
  private keepAliveInterval: any;
  private connectionTimeout: any;
  private readonly CONNECTION_TIMEOUT = 30000; // 30 seconds
  
  // Subjects for different message types
  private messageSubject = new Subject<WebSocketMessage>();
  private transcriptionSubject = new Subject<TranscriptionResult>();
  private stateChangeSubject = new Subject<StateChangeMessage>();
  private errorSubject = new Subject<string>();
  private connectionSubject = new Subject<boolean>();
  
  // Public observables
  public message$ = this.messageSubject.asObservable();
  public transcription$ = this.transcriptionSubject.asObservable();
  public stateChange$ = this.stateChangeSubject.asObservable();
  public error$ = this.errorSubject.asObservable();
  public connection$ = this.connectionSubject.asObservable();

  constructor() {}

  connect(sessionId: string): Promise<void> {
    return new Promise((resolve, reject) => {
      try {
        if (!sessionId) {
          const error = new Error('Session ID is required');
          reject(error);
          return;
        }

        // Close existing connection if any
        if (this.socket) {
          this.disconnect();
        }

        // Construct WebSocket URL
        const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
        const host = window.location.host;
        this.url = `${protocol}//${host}/ws/conversation/${sessionId}`;
        
        console.log(`🔌 Connecting to WebSocket: ${this.url}`);
        
        // Set connection timeout
        this.connectionTimeout = setTimeout(() => {
          const error = new Error('WebSocket connection timeout');
          console.error('❌ WebSocket connection timeout');
          this.handleConnectionError(error);
          reject(error);
        }, this.CONNECTION_TIMEOUT);
        
        this.socket = new WebSocket(this.url);
        
        this.socket.onopen = () => {
          clearTimeout(this.connectionTimeout);
          console.log('✅ WebSocket connected');
          this.reconnectAttempts = 0;
          this.connectionSubject.next(true);
          
          // Start keep-alive ping
          this.startKeepAlive();
          
          resolve();
        };
        
        this.socket.onmessage = (event) => {
          try {
            const message: WebSocketMessage = JSON.parse(event.data);
            this.handleMessage(message);
          } catch (error) {
            console.error('Failed to parse WebSocket message:', error);
            this.errorSubject.next('Invalid message format received');
          }
        };
        
        this.socket.onerror = (error) => {
          clearTimeout(this.connectionTimeout);
          console.error('❌ WebSocket error:', error);
          this.handleConnectionError(error);
          reject(error);
        };
        
        this.socket.onclose = (event) => {
          clearTimeout(this.connectionTimeout);
          console.log('🔌 WebSocket disconnected', {
            code: event.code,
            reason: event.reason,
            wasClean: event.wasClean
          });
          
          this.connectionSubject.next(false);
          this.stopKeepAlive();
          
          // Handle different close codes
          if (event.code === 1006) {
            // Abnormal closure
            this.errorSubject.next('WebSocket connection lost unexpectedly');
          } else if (event.code === 1000) {
            // Normal closure
            console.log('WebSocket closed normally');
          } else {
            // Other closure codes
            this.errorSubject.next(`WebSocket closed: ${event.reason || 'Unknown reason'}`);
          }
          
          // Attempt reconnection for non-normal closures
          if (event.code !== 1000 && this.reconnectAttempts < this.maxReconnectAttempts) {
            this.attemptReconnect(sessionId);
          }
        };
        
      } catch (error) {
        console.error('Failed to create WebSocket:', error);
        this.handleConnectionError(error);
        reject(error);
      }
    });
  }

  disconnect(): void {
    try {
      this.stopKeepAlive();
      clearTimeout(this.connectionTimeout);
      
      if (this.socket) {
        // Close with normal closure code
        this.socket.close(1000, 'Client disconnect');
        this.socket = null;
      }
      
      this.connectionSubject.next(false);
      this.reconnectAttempts = 0;
    } catch (error) {
      console.error('Error during disconnect:', error);
    }
  }

  send(message: WebSocketMessage): void {
    try {
      if (this.socket && this.socket.readyState === WebSocket.OPEN) {
        const messageStr = JSON.stringify(message);
        this.socket.send(messageStr);
      } else {
        const errorMsg = 'WebSocket is not connected';
        console.warn(errorMsg);
        this.errorSubject.next(errorMsg);
        
        // Optionally throw error for caller to handle
        throw new Error(errorMsg);
      }
    } catch (error) {
      console.error('Error sending message:', error);
      this.errorSubject.next('Failed to send message');
      throw error;
    }
  }

  sendAudioChunk(audioData: string): void {
    try {
      this.send({
        type: 'audio_chunk',
        data: audioData,
        timestamp: Date.now()
      });
    } catch (error) {
      console.error('Failed to send audio chunk:', error);
      // Don't re-throw for audio chunks to avoid interrupting stream
    }
  }

  sendControl(action: string, config?: any): void {
    try {
      this.send({
        type: 'control',
        action: action,
        config: config,
        timestamp: Date.now()
      });
    } catch (error) {
      console.error(`Failed to send control action '${action}':`, error);
      throw error;
    }
  }

  private handleMessage(message: WebSocketMessage): void {
    try {
      // Emit to general message stream
      this.messageSubject.next(message);
      
      // Handle specific message types
      switch (message.type) {
        case 'transcription':
          this.transcriptionSubject.next({
            text: message['text'] || '',
            is_final: message['is_final'] || false,
            confidence: message['confidence'] || 0
          });
          break;
          
        case 'state_change':
          this.stateChangeSubject.next({
            from: message['from'] || 'unknown',
            to: message['to'] || 'unknown'
          });
          break;
          
        case 'error':
          const errorMessage = message['message'] || 'Unknown error';
          this.errorSubject.next(errorMessage);
          
          // Handle specific error types
          if (message['error_type'] === 'race_condition') {
            console.warn('Race condition detected in WebSocket message');
          }
          break;
          
        case 'tts_audio':
          // Log TTS audio for debugging
          console.log('TTS audio message received', {
            has_data: !!message['data'],
            is_last: message['is_last'],
            chunk_index: message['chunk_index'],
            mime_type: message['mime_type']
          });
          break;
          
        case 'assistant_response':
        case 'pong':
        case 'session_started':
        case 'session_config': 
        case 'stt_ready':      
        case 'control':
          // These are handled by general message stream
          break;
          
        default:
          console.log('Unknown message type:', message.type);
      }
    } catch (error) {
      console.error('Error handling message:', error);
      this.errorSubject.next('Error processing message');
    }
  }
    
  private attemptReconnect(sessionId: string): void {
    this.reconnectAttempts++;
    const delay = Math.min(
      this.reconnectDelay * Math.pow(2, this.reconnectAttempts - 1),
      30000 // Max 30 seconds
    );
    
    console.log(`🔄 Attempting reconnection ${this.reconnectAttempts}/${this.maxReconnectAttempts} in ${delay}ms`);
    
    setTimeout(() => {
      this.connect(sessionId).catch(error => {
        console.error('Reconnection failed:', error);
        
        if (this.reconnectAttempts >= this.maxReconnectAttempts) {
          this.errorSubject.next('Maximum reconnection attempts reached');
        }
      });
    }, delay);
  }

  private handleConnectionError(error: any): void {
    const errorMessage = error?.message || 'WebSocket connection error';
    this.errorSubject.next(errorMessage);
    
    // Log additional error details
    console.error('WebSocket connection error details:', {
      message: errorMessage,
      type: error?.type,
      target: error?.target,
      timestamp: new Date().toISOString()
    });
  }

  // Keep-alive mechanism
  private startKeepAlive(): void {
    this.stopKeepAlive(); // Clear any existing interval
    
    this.keepAliveInterval = setInterval(() => {
      try {
        if (this.socket && this.socket.readyState === WebSocket.OPEN) {
          this.send({ type: 'ping', timestamp: Date.now() });
        } else {
          console.warn('Keep-alive: WebSocket not open');
          this.stopKeepAlive();
        }
      } catch (error) {
        console.error('Keep-alive error:', error);
        this.stopKeepAlive();
      }
    }, 30000); // Ping every 30 seconds
  }
  
  private stopKeepAlive(): void {
    if (this.keepAliveInterval) {
      clearInterval(this.keepAliveInterval);
      this.keepAliveInterval = null;
    }
  }

  isConnected(): boolean {
    return this.socket !== null && this.socket.readyState === WebSocket.OPEN;
  }

  getConnectionState(): string {
    if (!this.socket) return 'DISCONNECTED';
    
    switch (this.socket.readyState) {
      case WebSocket.CONNECTING:
        return 'CONNECTING';
      case WebSocket.OPEN:
        return 'CONNECTED';
      case WebSocket.CLOSING:
        return 'CLOSING';
      case WebSocket.CLOSED:
        return 'CLOSED';
      default:
        return 'UNKNOWN';
    }
  }

  // Get reconnection status
  getReconnectionInfo(): { attempts: number, maxAttempts: number, isReconnecting: boolean } {
    return {
      attempts: this.reconnectAttempts,
      maxAttempts: this.maxReconnectAttempts,
      isReconnecting: this.reconnectAttempts > 0 && this.reconnectAttempts < this.maxReconnectAttempts
    };
  }

  // Force reconnect
  forceReconnect(sessionId: string): Promise<void> {
    this.reconnectAttempts = 0;
    this.disconnect();
    return this.connect(sessionId);
  }
}