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...');
    
    try {
      if (this.primaryClient.testConnection) {
        const qwen3Available = await this.primaryClient.testConnection();
        
        if (qwen3Available) {
          console.log('✅ Qwen3 client is available and will be used for text generation');
          this.useQwen3 = true;
        } 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;
  }

  /**
   * 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'
    };
  }
}

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