import type { IOpusRecorder } from 'opus-recorder';

import { requestMeasure } from '../lib/fasterdom/fasterdom';

export type Result = { blob: Blob; duration: number; waveform: number[] };

const encoderPath = new URL('opus-recorder/dist/encoderWorker.min', import.meta.url).href;
const MIN_RECORDING_TIME = 1000;
const POLYFILL_OPTIONS = { encoderPath, reuseWorker: true };
const BLOB_PARAMS = { type: 'audio/ogg' };
const FFT_SIZE = 64;
const MIN_VOLUME = 0.1;

let opusRecorderPromise: Promise<{ default: IOpusRecorder }>;
let OpusRecorder: IOpusRecorder;
let mediaRecorder: IOpusRecorder;

export async function init() {
  // eslint-disable-next-line @typescript-eslint/no-misused-promises
  if (!opusRecorderPromise) {
    opusRecorderPromise = import('opus-recorder');
    OpusRecorder = (await opusRecorderPromise).default;
    mediaRecorder = new OpusRecorder(POLYFILL_OPTIONS);
  }

  return opusRecorderPromise;
}

export async function start(analyzerCallback: (volume: number) => void) {
  await startMediaRecorder();

  const startedAt = Date.now();
  let pausedAt: number;
  const chunks: Uint8Array[] = [];
  const waveform: number[] = [];

  mediaRecorder.ondataavailable = (typedArray) => {
    chunks.push(typedArray);
  };

  const releaseAnalyzer = subscribeToAnalyzer(mediaRecorder, (volume: number) => {
    waveform.push(volume * 255);
    analyzerCallback(volume);
  });

  return {
    stop: () => new Promise<Result>((resolve, reject) => {
      mediaRecorder.onstop = () => {
        resolve({
          blob: new Blob(chunks, BLOB_PARAMS),
          duration: Math.round(((pausedAt || Date.now()) - startedAt) / 1000),
          waveform,
        });
      };
      mediaRecorder.onerror = reject;

      const delayStop = Math.max(0, startedAt + MIN_RECORDING_TIME - Date.now());
      setTimeout(() => {
        mediaRecorder.stop();
        releaseAnalyzer();
      }, delayStop);
    }),
    pause: () => {
      const delayStop = Math.max(0, startedAt + MIN_RECORDING_TIME - Date.now());
      setTimeout(() => {
        mediaRecorder.pause();
        pausedAt = Date.now();
        releaseAnalyzer();
      }, delayStop);
    },
  };
}

async function startMediaRecorder() {
  await init();
  await mediaRecorder.start();
}

function subscribeToAnalyzer(recorder: IOpusRecorder, cb: (volume: number) => void) {
  const source = recorder.sourceNode;
  const analyser = source.context.createAnalyser();
  analyser.fftSize = FFT_SIZE;
  source.connect(analyser);

  const dataLength = analyser.frequencyBinCount;
  const dataArray = new Uint8Array(dataLength);
  let isDestroyed = false;

  function tick() {
    if (isDestroyed) {
      return;
    }

    analyser.getByteFrequencyData(dataArray);

    const sum = dataArray.reduce((acc, current) => acc + current, 0);
    const mean = (sum / dataLength);
    const volume = mean / 255;

    cb(volume < MIN_VOLUME ? 0 : volume);

    requestMeasure(tick);
  }

  tick();

  return () => {
    isDestroyed = true;
  };
}