import * as path from 'node:path';
import * as fs from 'node:fs';

import { assert } from 'chai';

import ffmpeg from '@mmomtchev/ffmpeg';
import { Muxer, Demuxer, AudioDecoder, AudioEncoder, AudioTransform, Discarder, AudioStreamDefinition } from '@mmomtchev/ffmpeg/stream';

const tempFile = path.resolve(__dirname, 'resampled.mkv');

describe('transcode', () => {
  afterEach('delete temporary', (done) => {
    if (!process.env.DEBUG_ALL && !process.env.DEBUG_MUXER)
      fs.rm(tempFile, done);
    else
      done();
  });

  it('generalized audio transcoding with with resampling', (done) => {
    const input = new Demuxer({ inputFile: path.resolve(__dirname, 'data', 'launch.mp4') });

    input.on('ready', () => {
      try {
        assert.lengthOf(input.streams, 2);
        assert.lengthOf(input.audio, 1);
        assert.lengthOf(input.video, 1);

        const videoDiscard = new Discarder();
        const audioInput = new AudioDecoder(input.audio[0]);
        const audioInputDefinition = audioInput.definition();

        const audioOutputDefinition = {
          type: 'Audio',
          codec: ffmpeg.AV_CODEC_AAC,
          bitRate: 128e3,
          sampleFormat: new ffmpeg.SampleFormat(ffmpeg.AV_SAMPLE_FMT_FLTP),
          sampleRate: 44100,
          channelLayout: new ffmpeg.ChannelLayout(ffmpeg.AV_CH_LAYOUT_STEREO)
        } as AudioStreamDefinition;
        const audioOutput = new AudioEncoder(audioOutputDefinition);

        // A standard Transform stream that resamples the audio
        const audioResampler = new AudioTransform({
          output: audioOutputDefinition,
          input: audioInputDefinition
        });

        const output = new Muxer({ outputFile: tempFile, outputFormat: 'mkv', streams: [audioOutput] });

        output.on('finish', done);
        input.on('error', done);
        output.on('error', done);

        input.video[0].pipe(videoDiscard);
        input.audio[0].pipe(audioInput).pipe(audioResampler).pipe(audioOutput).pipe(output.audio[0]);
      } catch (err) {
        done(err);
      }
    });
  });
});