import { v4 as uuidv4 } from 'uuid';
import { BotOrchestrator, OrchestratorCallbacks, OrchestratorOptions } from './bot/orchestrator';
import { BotSession, BotState, TranscriptEntry } from './types';
import { logger } from './utils/logger';
import { config } from './config';

/**
 * Manages all active bot sessions.
 * Each session connects to the Gateway independently via WebSocket.
 */
export class SessionManager {
  private _sessions: Map<string, BotOrchestrator> = new Map();

  constructor() {}

  /**
   * Initialize the session manager.
   */
  async initialize(): Promise<void> {
    logger.info('Initializing SessionManager...');
    logger.info(`Gateway WebSocket URL: ${config.gatewayWsUrl}`);
    // Sessions connect to Gateway individually when created
  }

  /**
   * Create a new bot session and join the meeting.
   * 
   * @param sessionId - Unique session ID
   * @param meetingUrl - Teams meeting URL
   * @param botName - Display name for the bot
   * @param instanceId - Feature instance ID (for Gateway routing)
   * @param gatewayWsUrl - Full WebSocket URL to connect back to Gateway (supports multi-instance)
   * @param language - BCP-47 language code for captions spoken language (e.g. "de-DE")
   */
  async createSession(
    sessionId: string,
    meetingUrl: string,
    botName?: string,
    instanceId?: string,
    gatewayWsUrl?: string,
    language?: string,
    botAccountEmail?: string,
    botAccountPassword?: string,
    transferMode?: string,
  ): Promise<void> {
    if (this._sessions.has(sessionId)) {
      logger.warn(`Session ${sessionId} already exists`);
      return;
    }

    logger.info(`Creating session ${sessionId} for meeting: ${meetingUrl}`);
    logger.info(`Gateway WebSocket URL: ${gatewayWsUrl || 'not provided, using config'}`);
    if (botAccountEmail) {
      logger.info(`Authenticated join as: ${botAccountEmail}`);
    }

    const callbacks: OrchestratorCallbacks = {
      onStateChange: (state, message) => {
        this._handleStateChange(sessionId, state, message);
      },
      onTranscript: (entry) => {
        this._handleTranscript(sessionId, entry);
      },
      onError: (error) => {
        this._handleError(sessionId, error);
      },
    };

    // Options for Gateway connection
    // Use the gatewayWsUrl from the request if provided (supports multi-instance gateways)
    // Otherwise fall back to config (for local development)
    const options: OrchestratorOptions = {
      gatewayWsUrl: gatewayWsUrl || config.gatewayWsUrl,
      instanceId: instanceId || 'default',
      language: language,
      botAccountEmail: botAccountEmail,
      botAccountPassword: botAccountPassword,
      transferMode: transferMode,
    };

    const orchestrator = new BotOrchestrator(
      sessionId,
      meetingUrl,
      botName || config.botName,
      callbacks,
      options
    );

    this._sessions.set(sessionId, orchestrator);

    // Start the bot asynchronously
    orchestrator.start().catch((error) => {
      logger.error(`Session ${sessionId} failed to start:`, error);
    });
  }

  /**
   * End a bot session and leave the meeting.
   * Robust: handles cases where the session was already cleaned up
   * (e.g. disconnected state removed it from the map).
   */
  async endSession(sessionId: string): Promise<void> {
    const orchestrator = this._sessions.get(sessionId);
    if (!orchestrator) {
      logger.warn(`Session ${sessionId} not found for endSession - may have already been cleaned up`);
      return;
    }

    logger.info(`Ending session ${sessionId}`);

    try {
      await orchestrator.stop();
    } catch (error) {
      logger.error(`Error stopping session ${sessionId}:`, error);
    } finally {
      // Always remove from map after explicit end
      this._sessions.delete(sessionId);
    }
  }

  /**
   * Play audio in a session's meeting.
   */
  async playAudio(
    sessionId: string,
    audioData: string,
    format: 'mp3' | 'wav' | 'pcm'
  ): Promise<void> {
    const orchestrator = this._sessions.get(sessionId);
    if (!orchestrator) {
      logger.warn(`Session ${sessionId} not found for audio playback`);
      return;
    }

    await orchestrator.playAudio(audioData, format);
  }

  /**
   * Get the status of a session.
   */
  getSessionStatus(sessionId: string): { state: string; error?: string } | null {
    const orchestrator = this._sessions.get(sessionId);
    if (!orchestrator) {
      return null;
    }

    return {
      state: orchestrator.state,
    };
  }

  /**
   * Get all active session IDs.
   */
  getActiveSessions(): string[] {
    return Array.from(this._sessions.keys());
  }

  /**
   * Shutdown all sessions.
   */
  async shutdown(): Promise<void> {
    logger.info('Shutting down SessionManager...');

    // End all sessions
    const sessionIds = Array.from(this._sessions.keys());
    await Promise.all(sessionIds.map((id) => this.endSession(id)));

    logger.info('SessionManager shutdown complete');
  }

  /**
   * Handle state changes from orchestrators.
   * 
   * IMPORTANT: Do NOT delete from _sessions on 'disconnected' state.
   * The orchestrator may enter 'disconnected' due to a transient WebSocket
   * drop or browser crash. If we delete here, the Gateway's subsequent
   * 'leave' command won't find the session in endSession().
   * Cleanup is done explicitly in endSession() or shutdown().
   * Only auto-remove on terminal 'error' state after a delay so the
   * Gateway still has time to call endSession() first.
   */
  private _handleStateChange(sessionId: string, state: BotState, message?: string): void {
    logger.info(`Session ${sessionId} state: ${state}${message ? ` - ${message}` : ''}`);

    if (state === 'error') {
      // Give Gateway a grace period to call endSession(), then auto-cleanup
      setTimeout(() => {
        if (this._sessions.has(sessionId)) {
          const orch = this._sessions.get(sessionId);
          if (orch && orch.state === 'error') {
            logger.info(`Auto-cleaning stale error session ${sessionId}`);
            this._sessions.delete(sessionId);
          }
        }
      }, 30000); // 30s grace period
    }
    // 'disconnected' state: do NOT delete - let endSession() handle it
  }

  /**
   * Handle transcripts from orchestrators.
   */
  private _handleTranscript(sessionId: string, entry: TranscriptEntry): void {
    logger.debug(`Session ${sessionId} transcript: [${entry.speaker}] ${entry.text}`);
    // Transcripts are sent to Gateway by the orchestrator directly
  }

  /**
   * Handle errors from orchestrators.
   */
  private _handleError(sessionId: string, error: Error): void {
    logger.error(`Session ${sessionId} error:`, error);
    // Errors are sent to Gateway by the orchestrator directly
  }
}