import { Howl } from "howler";

export type PlaybackState = {
  isPlaying: boolean;
  url: string | null;
  name: string | null;
  elapsed: number;
  duration: number;
};

type Listener = (s: PlaybackState) => void;

const MAX_SECONDS = 6;
const FADE_MS = 500;

let state: PlaybackState = {
  isPlaying: false,
  url: null,
  name: null,
  elapsed: 0,
  duration: MAX_SECONDS,
};

const listeners = new Set<Listener>();

let howlInstance: Howl | null = null;
let soundId: number | null = null;
let stopTimer: ReturnType<typeof setTimeout> | null = null;
let progressTimer: ReturnType<typeof setInterval> | null = null;

function emit() {
  listeners.forEach(fn => fn(state));
}

function resetTimers() {
  if (stopTimer) clearTimeout(stopTimer);
  if (progressTimer) clearInterval(progressTimer);
  stopTimer = null;
  progressTimer = null;
}

function stopSound() {
  if (howlInstance && soundId !== null) {
    howlInstance.stop(soundId);
  }
  howlInstance = null;
  soundId = null;
}

export function getPlaybackState(): PlaybackState {
  return state;
}

export function subscribe(fn: Listener): () => void {
  listeners.add(fn);
  return () => listeners.delete(fn);
}

export function playUrl(url: string, name?: string) {
  stopCurrent();

  const displayName = name || url.split("/").pop() || url;

  howlInstance = new Howl({
    src: [url],
    format: url.endsWith(".mp3") ? ["mp3"] : url.endsWith(".ogg") ? ["ogg"] : ["mp3", "ogg"],
    volume: 0.4,
  });

  soundId = howlInstance.play();

  state = { isPlaying: true, url, name: displayName, elapsed: 0, duration: MAX_SECONDS };
  emit();

  // Progress tick
  progressTimer = setInterval(() => {
    if (howlInstance && soundId !== null) {
      const seek = howlInstance.seek(soundId) as number;
      state = { ...state, elapsed: seek };
      emit();
    }
  }, 100);

  // Cap at MAX_SECONDS with fadeout
  const fadeStart = (MAX_SECONDS - FADE_MS / 1000) * 1000;
  stopTimer = setTimeout(() => {
    if (howlInstance && soundId !== null) {
      try { howlInstance.fade(0.4, 0, FADE_MS, soundId); } catch {}
      setTimeout(() => stopCurrent(), FADE_MS);
    }
  }, fadeStart);

  // Natural end
  howlInstance.on("end", () => stopCurrent());
}

export function stopCurrent() {
  stopSound();
  resetTimers();
  state = { isPlaying: false, url: null, name: null, elapsed: 0, duration: MAX_SECONDS };
  emit();
}