src/common/clients/fastapi.client.ts

import axios, { AxiosInstance } from 'axios';
import { Logger } from '@nestjs/common';
import FormData from 'form-data';
import { Readable } from 'stream';

export interface IndexPdfResponse {
  pdf_name: string;
  chunks_indexed: number;
  conversation_id: string;
}

export interface FastApiQuizResponse {
  title?: string;
  description?: string;
  passing_score?: number;
  questions: Array<{
    order: number;
    topic: string;
    difficulty: 'easy' | 'medium' | 'hard';
    question_text: string;
    options: Array<{ id: string; text: string }>;
    correct_answer: string;
    explanation?: string;
  }>;
  metadata?: Record<string, unknown>;
}

export interface AtRiskAnalysisResponse {
  students: Array<{
    sender_id: string;
    sender_name: string;
    signals?: {
      stuck_phrases?: Array<{ text: string; suggested_points: number }>;
      frustration_phrases?: Array<{ text: string; suggested_points: number }>;
      unanswered_questions?: Array<{ text: string; suggested_points: number }>;
    };
  }>;
}

export class FastApiClient {
  private readonly client: AxiosInstance;

  constructor(logger: Logger, fastApiUrl?: string, private readonly defaultTimeout = 60000) {
    const baseUrl = fastApiUrl || process.env.FASTAPI_URL || 'http://localhost:8000/api/v1';
    this.client = axios.create({
      baseURL: baseUrl,
      timeout: this.defaultTimeout,
    });
    this.logger = logger;
  }

  private readonly logger: Logger;

  async genQuiz(content: string, kQuestion: number): Promise<FastApiQuizResponse> {
    this.logger.log(`[FastAPI] genQuiz called: content=${content.length} chars, ${kQuestion} questions`);
    try {
      const response = await this.client.post('/gen_quiz', {
        content,
        k_question: kQuestion,
      });
      this.logger.log(`[FastAPI] genQuiz response: ${JSON.stringify({ hasData: !!response.data, keys: Object.keys(response.data || {}) })}`);
      return response.data;
    } catch (error: unknown) {
      const axiosError = error as { response?: { status?: number; data?: unknown }; message?: string };
      this.logger.error(
        `[FastAPI] genQuiz failed: ${axiosError.response?.status || 'N/A'} ${JSON.stringify(axiosError.response?.data || {})}`,
        axiosError.message || 'Unknown error'
      );
      throw error;
    }
  }

  async analyzeAtRisk(roomIds: string[], hours: number): Promise<AtRiskAnalysisResponse> {
    const response = await this.client.post('/at-risk/analyze', {
      room_ids: roomIds,
      hours,
    });
    return response.data;
  }

  /**
   * Index PDF vào Qdrant knowledge base
   */
  async indexPdf(conversationId: string, file: Buffer, filename: string): Promise<IndexPdfResponse> {
    const form = new FormData();
    form.append('conversation_id', conversationId);
    // Use form-data package with Readable stream for proper file upload
    form.append('file', Readable.from(file), {
      filename,
      contentType: 'application/pdf'
    });

    const response = await this.client.post('/index_pdf', form, {
      headers: form.getHeaders()
    });
    return response.data;
  }
}