quivr/frontend/app/chat/[chatId]/hooks/useQuestion.ts

/* eslint-disable max-lines */

import { useTranslation } from 'react-i18next';

import { useBrainContext } from '@/lib/context/BrainProvider/hooks/useBrainContext';
import { useChatContext } from '@/lib/context/ChatProvider/hooks/useChatContext';
import { useFetch } from '@/lib/hooks';

import { ChatHistory, ChatQuestion } from '../types';

interface UseChatService {
  addStreamQuestion: (
    chatId: string,
    chatQuestion: ChatQuestion
  ) => Promise<void>;
}

export const useQuestion = (): UseChatService => {
  const { fetchInstance } = useFetch();
  const { updateStreamingHistory } = useChatContext();
  const { currentBrain } = useBrainContext();

  const { t } = useTranslation(['chat']);

  const handleStream = async (
    reader: ReadableStreamDefaultReader<Uint8Array>
  ): Promise<void> => {
    const decoder = new TextDecoder('utf-8');

    const handleStreamRecursively = async () => {
      const { done, value } = await reader.read();

      if (done) {
        return;
      }

      const dataStrings = decoder
        .decode(value)
        .trim()
        .split('data: ')
        .filter(Boolean);

      dataStrings.forEach((data) => {
        try {
          const parsedData = JSON.parse(data) as ChatHistory;
          updateStreamingHistory(parsedData);
        } catch (error) {
          console.error(t('errorParsingData', { ns: 'chat' }), error);
        }
      });

      await handleStreamRecursively();
    };

    await handleStreamRecursively();
  };

  const addStreamQuestion = async (
    chatId: string,
    chatQuestion: ChatQuestion
  ): Promise<void> => {
    const headers = {
      'Content-Type': 'application/json',
      Accept: 'text/event-stream',
    };
    const body = JSON.stringify(chatQuestion);
    console.log('Calling API...');
    try {
      const response = await fetchInstance.post(
        `/chat/${chatId}/question/stream?brain_id=${currentBrain?.id ?? ''}`,
        body,
        headers
      );

      if (response.body === null) {
        throw new Error(t('resposeBodyNull', { ns: 'chat' }));
      }

      console.log(t('receivedResponse'), response);
      await handleStream(response.body.getReader());
    } catch (error) {
      console.error(t('errorCallingAPI', { ns: 'chat' }), error);
    }
  };

  return {
    addStreamQuestion,
  };
};