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

import fetchPonyfill from 'fetch-ponyfill';
import Handlebars from 'handlebars';
import { resolve } from 'path';
import { readFile } from 'fs/promises';
import * as config from './config';
import { OpenAiParams } from './common';

export interface MakeAiCallParams {
  prompts: string[];
  openAiParams: OpenAiParams;
}

export class AiCallError extends Error {
  constructor(message: string, public readonly response: Response) {
    super(message);
    this.name = 'AiCallError';
  }
}

const makeAiCall = async (params: MakeAiCallParams): Promise<string> => {
  const {
    prompts,
    openAiParams: {
      apiKey,
      organizationId,
      model = 'gpt-3.5-turbo',
      temperature = 0.6,
    },
  } = params;

  const headers: Record<string, string> = {
    'Content-Type': 'application/json',
    Accept: 'application/json',
    Authorization: `Bearer ${apiKey}`,
  };

  if (organizationId) {
    headers['OpenAI-Organization'] = organizationId;
  }

  const { fetch } = fetchPonyfill();
  const response = await fetch(
    new URL('/v1/chat/completions', 'https://api.openai.com'),
    {
      method: 'POST',
      headers,
      body: JSON.stringify({
        model,
        temperature,
        messages: [
          {
            role: 'user',
            content: prompts[Math.floor(Math.random() * prompts.length)].trim(),
          },
        ],
      }),
    },
  );

  if (!response.ok) {
    const { error } = await response.json();
    throw new AiCallError(`OpenAI API call failed with status ${response.status}: ${error.message}`, response);
  }

  const { choices } = await response.json();

  // should we use all the response choices?
  return choices[0].message.content;
};

const compilePrompts = async (filename: string, params: Record<string, unknown>): Promise<string[]> => {
  const rawPromptText = await readFile(resolve(config.openAi.promptsDir, filename), 'utf-8');
  const fill = Handlebars.compile(rawPromptText, { noEscape: true });
  const filledText = fill(params);
  return filledText.split('---').map((s) => s.trim());
};

export interface NormalizeTranscriptTextParams {
  rawTranscriptText: string,
  openAiParams: OpenAiParams,
}

export const normalizeTranscriptText = async (params: NormalizeTranscriptTextParams) => {
  const {
    rawTranscriptText,
    openAiParams,
  } = params;
  const prompts = await compilePrompts(
    'normalize-transcript-text.hbs',
    {
      transcript: rawTranscriptText,
    },
  );

  return makeAiCall({
    prompts,
    openAiParams,
  });
};

export interface SummarizeTranscriptParams {
  normalizedTranscript: string,
  openAiParams: OpenAiParams,
}

export const summarizeTranscript = async (params: SummarizeTranscriptParams) => {
  const {
    normalizedTranscript,
    openAiParams,
  } = params;
  const prompts = await compilePrompts(
    'summarize-transcript.hbs',
    {
      transcript: normalizedTranscript,
    },
  );

  return makeAiCall({
    prompts,
    openAiParams,
  });
};