utils/AvatarRender.js

import { spawn } from 'child_process';
import os from 'os';
import path from 'path';
import fs from 'fs';
import Bubble from './bubble/Bubble.js';

const ffmpegLocation = os.platform() === 'win32' ? 'ffmpeg.exe' : 'ffmpeg';

export class AvatarRenderer {

  validateCaption(originalManuscript) {
    let captionFiles = originalManuscript.transcript.map(item => item.audioCaptionFile);
    // make sure the caption files are in ass format and exist
    for (let captionFile of captionFiles) {
      if (!captionFile || !captionFile.endsWith('.ass')) {
        throw new Error('Invalid caption file format. Expected .ass files for item ' + (captionFiles.indexOf(captionFile) + 1) + '. Did you forget to use `caption` plugin?');
      }
    }
    return true;
  }


  async doRender(jobId, originalManuscript, onLog, npmScript, options, controller) {
    const outDir = path.join(process.cwd(), 'out');
    if (!fs.existsSync(outDir)) fs.mkdirSync(outDir, { recursive: true });

    const tempFiles = []; // track intermediate files for cleanup
    const sectionCaptionedVideos = [];

    // Step 1: For each section, concat its media files and burn its captions
    for (let i = 0; i < originalManuscript.transcript.length; i++) {
      const section = originalManuscript.transcript[i];
      const sectionVideos = section.mediaAbsPaths?.map(m => m.path) || [];
      if (!sectionVideos.length) {
        onLog && onLog(`Warning: Section ${i} has no mediaAbsPaths, skipping.\n`);
        continue;
      }

      let sectionVideo;

      // Concat all media files within this section
      if (sectionVideos.length === 1) {
        sectionVideo = sectionVideos[0];
      } else {
        const baseDirOfVideos = path.dirname(sectionVideos[0]);
        const concatList = path.join(baseDirOfVideos, `${jobId}_section${i}_concat_list.txt`);
        fs.writeFileSync(concatList, sectionVideos.map(f => `file '${path.basename(f)}'`).join('\n'));
        tempFiles.push(concatList);

        sectionVideo = path.join(outDir, `${jobId}_section${i}_concat.mp4`);
        const concatArgs = [
          '-f', 'concat',
          '-safe', '0',
          '-i', concatList,
          '-c', 'copy',
          '-y', sectionVideo
        ];
        onLog && onLog(`Concatenating ${sectionVideos.length} media files for section ${i}...\n`);
        await this.runFFmpeg(concatArgs, controller, onLog);
        tempFiles.push(sectionVideo);
      }

      // First apply bubbles (so they are below caption layer)
      let sourceAfterBubbles = sectionVideo;
      if (section.bubbles && Array.isArray(section.bubbles) && section.bubbles.length) {
        const bubbledFile = path.join(outDir, `${jobId}_section${i}_bubbled.mp4`);
        try {
          onLog && onLog(`Applying ${section.bubbles.length} bubble(s) to section ${i}...\n`);
          await Bubble.makeBubble(sectionVideo, section.bubbles, bubbledFile, onLog);
          tempFiles.push(bubbledFile);
          sourceAfterBubbles = bubbledFile;
        } catch (e) {
          onLog && onLog(`Bubble application failed for section ${i}, using original: ${e}\n`);
          sourceAfterBubbles = sectionVideo;
        }
      }

      // Then burn captions on top of bubbled video (so captions stay visible)
      const captionFile = section.audioCaptionFile;
      if (captionFile && captionFile.endsWith('.ass')) {
        const subbedFile = path.join(outDir, `${jobId}_section${i}_subbed.mp4`);
        const esc = captionFile.replace(/\\/g, '/').replace(/:/g, '\\:');
        const subArgs = [
          '-i', sourceAfterBubbles,
          '-vf', `subtitles='${esc}'`,
          '-c:a', 'copy',
          '-y', subbedFile
        ];
        onLog && onLog(`Burning captions for section ${i} after bubbles...\n`);
        await this.runFFmpeg(subArgs, controller, onLog);
        tempFiles.push(subbedFile);
        sectionCaptionedVideos.push(subbedFile);
      } else {
        sectionCaptionedVideos.push(sourceAfterBubbles);
      }
    }

    if (!sectionCaptionedVideos.length) throw new Error('No mediaAbsPaths found in any transcript section.');

    // Step 2: Concat all captioned section videos together
    let videoWithSubs;
    if (sectionCaptionedVideos.length === 1) {
      videoWithSubs = sectionCaptionedVideos[0];
    } else {
      const finalConcatList = path.join(outDir, `${jobId}_final_concat_list.txt`);
      fs.writeFileSync(finalConcatList, sectionCaptionedVideos.map(f => `file '${f}'`).join('\n'));
      tempFiles.push(finalConcatList);

      videoWithSubs = path.join(outDir, `${jobId}_all_sections.mp4`);
      const finalConcatArgs = [
        '-f', 'concat',
        '-safe', '0',
        '-i', finalConcatList,
        '-c', 'copy',
        '-y', videoWithSubs
      ];
      onLog && onLog(`Concatenating ${sectionCaptionedVideos.length} captioned sections...\n`);
      await this.runFFmpeg(finalConcatArgs, controller, onLog);
      tempFiles.push(videoWithSubs);
    }

    // Step 3: Add background music if present
    const { bgMusic, bgMusicVolume = 0.25 } = originalManuscript;
    const resultFile = path.join(outDir, `${jobId}_final.mp4`);
    if (bgMusic) {
      const voiceVolume = options?.voiceVolume || 1.5;
      const musicArgs = [
        '-i', videoWithSubs,
        '-i', bgMusic,
        '-filter_complex', `[0:a]volume=${voiceVolume}[voice];[1:a]volume=${bgMusicVolume}[bgm];[voice][bgm]amix=inputs=2:duration=first:dropout_transition=2:normalize=0[mixeda]`,
        '-map', '0:v',
        '-map', '[mixeda]',
        '-c:v', 'copy',
        '-c:a', 'aac',
        '-y', resultFile
      ];
      await this.runFFmpeg(musicArgs, controller, onLog);
    } else {
      // If the final video is one of the temp files, copy it; otherwise rename
      if (tempFiles.includes(videoWithSubs)) {
        fs.copyFileSync(videoWithSubs, resultFile);
      } else {
        fs.renameSync(videoWithSubs, resultFile);
      }
    }

    // Cleanup intermediate files — keep only the final resultFile and the manuscript JSON
    const manuscriptPath = path.join(process.cwd(), 'public', 'original_manuscript.json');
    for (const f of tempFiles) {
      if (!f) continue;
      try {
        const abs = path.resolve(f);
        // never delete the final result file or the manuscript file
        if (abs === path.resolve(resultFile)) continue;
        if (abs === path.resolve(manuscriptPath)) continue;
        if (fs.existsSync(abs)) {
          try { fs.unlinkSync(abs); onLog && onLog(`Deleted temp file: ${abs}\n`); } catch (e) { onLog && onLog(`Failed to delete temp file ${abs}: ${e}\n`); }
        }
      } catch (e) {
        onLog && onLog(`Error while cleaning temp file ${f}: ${e}\n`);
      }
    }

    return resultFile;
  }



  runFFmpeg(args, controller, onLog) {
    console.log('FFMPEG cmd:', args.join(' '));

    return new Promise((resolve, reject) => {
      const p = spawn(ffmpegLocation, args, { detached: true });

      if (controller) controller.stop = () => p.kill('SIGKILL');

      p.stderr.on('data', d => onLog && onLog(d.toString()));
      p.stdout.on('data', d => onLog && onLog(d.toString()));

      p.on('close', code => code === 0 ? resolve() : reject(new Error(`ffmpeg exited ${code}`)));
      p.on('error', reject);
    });
  }
}