src/lib/services/textGenerationClient.ts

/**
 * Text Generation Client Manager
 * Provides unified interface for text generation with automatic fallback
 * Primary: Qwen3 (Qwen/Qwen3-Demo), Fallback: Zephyr-7B (Fraser/zephyr-7b)
 */

import { qwen3Client } from './qwen3Client';

interface TextGenerationClient {
  predict(endpoint: string, params: any[]): Promise<{data: any[]}>;
  testConnection?(): Promise<boolean>;
}

class TextGenerationManager {
  private primaryClient: TextGenerationClient;
  private fallbackClient: TextGenerationClient | null = null;
  private useQwen3: boolean = true;
  private connectionTested: boolean = false;

  constructor() {
    this.primaryClient = qwen3Client;
  }

  /**
   * Set the fallback client (Zephyr-7B)
   */
  setFallbackClient(client: TextGenerationClient) {
    this.fallbackClient = client;
  }

  /**
   * Test connection and determine which client to use
   */
  async initialize(): Promise<void> {
    if (this.connectionTested) return;

    console.log('🔍 Testing Qwen3 connection with improved verification...');
    
    try {
      if (this.primaryClient.testConnection) {
        // Add timeout wrapper for connection test
        const connectionTestPromise = this.primaryClient.testConnection();
        const timeoutPromise = new Promise<boolean>((_, reject) => {
          setTimeout(() => reject(new Error('Connection test timeout')), 15000); // 15 second timeout
        });

        const qwen3Available = await Promise.race([connectionTestPromise, timeoutPromise]);
        
        if (qwen3Available) {
          console.log('✅ Qwen3 client is available and will be used for text generation');
          this.useQwen3 = true;
          
          // Perform a secondary validation test to ensure real functionality
          await this.performSecondaryValidation();
        } else {
          console.log('⚠️ Qwen3 client is not available, falling back to Zephyr-7B');
          this.useQwen3 = false;
        }
      }
    } catch (error) {
      console.error('Failed to test Qwen3 connection:', error);
      console.log('⚠️ Falling back to Zephyr-7B due to connection error');
      this.useQwen3 = false;
    }

    this.connectionTested = true;
  }

  /**
   * Perform secondary validation to ensure Qwen3 is actually working
   */
  private async performSecondaryValidation(): Promise<void> {
    try {
      console.log('🔧 Performing secondary validation of Qwen3 functionality...');
      
      // Test with a specific request that should return predictable content
      const validationResult = await Promise.race([
        this.primaryClient.predict('/chat', [
          'Respond with exactly this text: "VALIDATION_SUCCESS"',
          [],
          'You are a helpful assistant. Follow instructions exactly as given.',
          20, // Very small token limit
          0.1, // Low temperature for deterministic output
          0.9,
          10,
          1.0
        ]),
        new Promise<any>((_, reject) => {
          setTimeout(() => reject(new Error('Validation timeout')), 10000); // 10 second timeout
        })
      ]);

      const response = validationResult?.data?.[0] || '';
      const isValidResponse = typeof response === 'string' && 
                             response.length > 0 && 
                             !response.includes('temporarily unavailable') &&
                             !response.includes('using_fallback');

      if (!isValidResponse) {
        console.warn('⚠️ Secondary validation failed - Qwen3 responses seem invalid, switching to fallback');
        this.useQwen3 = false;
      } else {
        console.log('✅ Secondary validation passed - Qwen3 is fully functional');
      }
    } catch (error) {
      console.warn('⚠️ Secondary validation failed with error, switching to fallback:', error);
      this.useQwen3 = false;
    }
  }

  /**
   * Get the active client for text generation
   */
  private getActiveClient(): TextGenerationClient {
    if (this.useQwen3) {
      return this.primaryClient;
    } else if (this.fallbackClient) {
      return this.fallbackClient;
    } else {
      console.warn('No fallback client available, using Qwen3 client');
      return this.primaryClient;
    }
  }

  /**
   * Predict method with automatic fallback
   */
  async predict(endpoint: string, params: any[]): Promise<{data: any[]}> {
    // Ensure initialization has been attempted
    if (!this.connectionTested) {
      await this.initialize();
    }

    const activeClient = this.getActiveClient();
    const clientName = this.useQwen3 ? 'Qwen3' : 'Zephyr-7B';
    
    console.log(`🤖 Using ${clientName} for text generation`);

    try {
      const result = await activeClient.predict(endpoint, params);
      return result;
    } catch (error) {
      console.error(`${clientName} prediction failed:`, error);
      
      // If primary client fails and we have a fallback, try it
      if (this.useQwen3 && this.fallbackClient) {
        console.log('🔄 Qwen3 failed, trying fallback to Zephyr-7B...');
        try {
          const fallbackResult = await this.fallbackClient.predict(endpoint, params);
          // Mark for future calls to use fallback
          this.useQwen3 = false;
          return fallbackResult;
        } catch (fallbackError) {
          console.error('Fallback client also failed:', fallbackError);
          throw new Error(`Both primary (${clientName}) and fallback clients failed`);
        }
      }
      
      throw error;
    }
  }

  /**
   * Force switch to Qwen3
   */
  useQwen3Client() {
    this.useQwen3 = true;
    console.log('🔄 Switched to Qwen3 client');
  }

  /**
   * Force switch to fallback (Zephyr-7B)
   */
  useFallbackClient() {
    if (this.fallbackClient) {
      this.useQwen3 = false;
      console.log('🔄 Switched to fallback (Zephyr-7B) client');
    } else {
      console.warn('No fallback client available');
    }
  }

  /**
   * Get current client status
   */
  getStatus() {
    return {
      usingQwen3: this.useQwen3,
      hasFallback: this.fallbackClient !== null,
      connectionTested: this.connectionTested,
      activeClient: this.useQwen3 ? 'Qwen3' : 'Zephyr-7B'
    };
  }

  /**
   * Reset connection testing to allow re-initialization
   */
  resetConnectionTest() {
    this.connectionTested = false;
    console.log('🔄 Connection test reset - will re-test on next prediction');
  }

  /**
   * Force re-test connection and re-initialize
   */
  async retestConnection(): Promise<void> {
    this.connectionTested = false;
    await this.initialize();
  }
}

// Export singleton instance
export const textGenerationManager = new TextGenerationManager();