/**
 * Copyright (c) Double Symmetry GmbH
 * Commercial use requires a license. See https://rntp.dev/pricing
 */

import {
  headersOf,
  uriOf,
  type AudioEngine,
  type EngineCallbacks,
  type EngineProvider,
  type ResolvedMediaItem,
} from './AudioEngine';
import { HtmlAudioEngine } from './HtmlAudioEngine';
import { ShakaEngine } from './ShakaEngine';

export type StreamKind = 'hls' | 'dash' | null;

const HLS_MIME = /application\/(x-mpegurl|vnd\.apple\.mpegurl)/i;
const DASH_MIME = /application\/dash\+xml/i;

export function sniffStreamKind(
  item: Pick<ResolvedMediaItem, 'url' | 'mimeType'>
): StreamKind {
  if (item.mimeType) {
    if (HLS_MIME.test(item.mimeType)) return 'hls';
    if (DASH_MIME.test(item.mimeType)) return 'dash';
    return null; // explicit mimeType wins over extension sniffing
  }
  const path = uriOf(item.url).split(/[?#]/, 1)[0]!.toLowerCase();
  if (path.endsWith('.m3u8')) return 'hls';
  if (path.endsWith('.mpd')) return 'dash';
  return null;
}

function canPlayHlsNatively(): boolean {
  const el = document.createElement('audio');
  return el.canPlayType('application/vnd.apple.mpegurl') !== '';
}

/**
 * One engine instance per kind, lazily constructed. HLS prefers the native
 * element where supported (Safari), matching AVFoundation behavior on iOS.
 *
 * Each cached engine captures the `callbacks` from its first `engineFor` call
 * and reuses them; subsequent calls ignore the passed `callbacks`. This is safe
 * because a single {@link WebTrackPlayer} owns one provider and always passes
 * the same stable callbacks object — do not share one provider across players.
 */
export class DefaultEngineProvider implements EngineProvider {
  private html: HtmlAudioEngine | null = null;
  private shaka: ShakaEngine | null = null;

  engineFor(item: ResolvedMediaItem, callbacks: EngineCallbacks): AudioEngine {
    const kind = sniffStreamKind(item);
    const needsShaka =
      kind === 'dash' ||
      (kind === 'hls' && !canPlayHlsNatively()) ||
      headersOf(item.url) != null;
    if (needsShaka) {
      if (!this.shaka) this.shaka = new ShakaEngine(callbacks);
      return this.shaka;
    }
    if (!this.html) this.html = new HtmlAudioEngine(callbacks);
    return this.html;
  }

  destroy(): void {
    this.html?.destroy();
    this.shaka?.destroy();
    this.html = null;
    this.shaka = null;
  }
}