webvideo-transcript-summary-core/src/summarizer.ts

import { OpenAi, createAiClient } from '@modal-sh/mio-ai';
import { EventEmitter } from 'events';
import { BaseTranscriptItem } from './transcript';

export type DataEventCallback = (event: string) => void;

export type ErrorEventCallback = (event: Error) => void;

export interface SummarizerEventEmitter<T = unknown> extends NodeJS.EventEmitter {
  normalize(transcriptItems: T[]): Promise<string>;
  summarize(transcript: string): void;
  on(eventType: 'data', callback: DataEventCallback): this;
  on(eventType: 'error', callback: ErrorEventCallback): this;
  on(eventType: 'end', callback: () => void): this;
}

export class SummarizerEventEmitterImpl<T extends BaseTranscriptItem> extends EventEmitter {
  private readonly openAiClient: OpenAi.PlatformEventEmitter;

  constructor(params: OpenAi.Configuration) {
    super();
    this.openAiClient = createAiClient({
      platform: OpenAi.PLATFORM_ID,
      platformConfiguration: params,
    });
  }

  normalize(transcript: T[]) {
    return new Promise<string>((resolve, reject) => {
      this.openAiClient.once<OpenAi.CreateEditDataEvent>('data', (data) => {
        const normalizedTranscript = data.choices[0].text;
        resolve(normalizedTranscript);
      });

      this.openAiClient.once('error', (error) => {
        reject(error);
      });

      this.openAiClient.createEdit({
        input: transcript.map((item) => item.text).join(' '),
        instruction: 'Put proper punctuation and correct capitalization',
        model: OpenAi.EditModel.TEXT_DAVINCI_EDIT_001,
      });
    });
  }

  summarize(normalizedTranscript: string) {
    const listener = (data: OpenAi.ChatCompletionChunkDataEvent) => {
      const theContent = data.choices[0].delta.content;
      if (typeof theContent !== 'string') {
        return;
      }

      this.emit('data', theContent)
    };

    this.openAiClient.on<OpenAi.ChatCompletionChunkDataEvent>('data', listener);

    this.openAiClient.once('error', (error) => {
      this.openAiClient.off('data', listener);
      this.emit('error', error);
    });

    this.openAiClient.once('end', () => {
      this.openAiClient.off('data', listener);
      this.emit('end');
    });

    this.openAiClient.createChatCompletion({
      model: OpenAi.ChatCompletionModel.GPT_3_5_TURBO,
      messages: [
        {
          role: OpenAi.MessageRole.SYSTEM,
          content: 'You are working on video transcripts.',
        },
        {
          role: OpenAi.MessageRole.USER,
          content: `Summarize the following transcript:\n\n${normalizedTranscript}`,
        },
      ],
    });
  }
}