webvideo-clip-core/src/video-types/youtube/index.ts

import { EventEmitter } from 'events';
import { spawnSync } from 'child_process';
import { readFileSync, unlinkSync } from 'fs';
import { CreateBaseClipperParams, FILE_TYPES, VideoClipEventEmitter } from '../../common';
import { getFileExtension, constructDefaultDownloadArgs } from './utilities';

export interface CreateYouTubeClipperParams extends CreateBaseClipperParams {
  downloaderExecutablePath?: string;
}

export class YouTubeVideoClipEventEmitter extends EventEmitter implements VideoClipEventEmitter {
  constructor(private readonly params: CreateYouTubeClipperParams) {
    super();
  }

  process() {
    if (!this.params.downloaderExecutablePath) {
      this.emit('error', new Error('Downloader not found.'));
      this.emit('end');
      return;
    }

    const fileExtension = getFileExtension(
      this.params.downloaderExecutablePath,
      this.params.url,
    );
    const cacheFilename = `output.${fileExtension}`; // todo label this on the cache
    const downloadArgs = constructDefaultDownloadArgs(
      cacheFilename,
      this.params.url,
      this.params.start,
      this.params.end,
    );

    this.emit('process', {
      type: 'download',
      phase: 'start',
      command: `${this.params.downloaderExecutablePath} ${downloadArgs.join(' ')}`,
    });
    const downloaderProcess = spawnSync(
      this.params.downloaderExecutablePath,
      downloadArgs,
    );
    if (downloaderProcess.error) {
      this.emit('error', downloaderProcess.error);
      this.emit('end');
      return;
    }
    this.emit('process', {
      type: 'download',
      phase: 'success',
    });

    const output = readFileSync(cacheFilename);
    unlinkSync(cacheFilename);
    this.emit('success', {
      contentType: FILE_TYPES[fileExtension],
      content: output,
    });
    this.emit('end');
  }
}