/**
 * Theme audio for the room code lobby: reload, volume, loop, and fade-out.
 * Implements the overlay component contract: init, activate, deactivate, update, getStatus.
 */

/**
 * @typedef {object} AudioControllerInputs
 * @property {HTMLInputElement} enabled
 * @property {HTMLInputElement} volume
 * @property {HTMLInputElement} soundUrl
 */

class AudioController {
  /** @type {HTMLAudioElement | null} */
  #audio = null;

  /** @type {AudioControllerInputs | null} */
  #inputs = null;

  /** @type {boolean} */
  #active = false;

  /** @type {ReturnType<typeof setInterval> | null} */
  #fadeInterval = null;

  /**
   * @param {HTMLAudioElement} audioElement
   * @param {AudioControllerInputs} inputs
   */
  init(audioElement, inputs) {
    this.#audio = audioElement;
    this.#inputs = inputs;
  }

  /**
   * @param {object} [_ctx]
   */
  activate(_ctx) {
    this.deactivate();

    this.#active = true;

    const inputs = this.#inputs;
    const audio = this.#audio;
    if (!inputs || !audio) {
      return;
    }

    if (!inputs.enabled.checked) {
      return;
    }

    audio.src = inputs.soundUrl.value;
    audio.load();
    audio.volume = parseFloat(inputs.volume.value);
    audio.loop = true;
    audio.currentTime = 0;
    audio.play().catch((error) => {
      console.log('Audio playback failed:', error);
    });
  }

  deactivate() {
    this.#active = false;

    if (this.#fadeInterval != null) {
      clearInterval(this.#fadeInterval);
      this.#fadeInterval = null;
    }

    const audio = this.#audio;
    const inputs = this.#inputs;
    if (!audio) {
      return;
    }

    audio.pause();
    audio.currentTime = 0;

    if (inputs) {
      audio.volume = parseFloat(inputs.volume.value);
    }
  }

  /**
   * @param {object} [_ctx]
   */
  update(_ctx) {
    // No in-state audio updates.
  }

  getStatus() {
    const audio = this.#audio;
    const inputs = this.#inputs;

    return {
      active: this.#active,
      enabled: inputs?.enabled.checked ?? false,
      playing: Boolean(audio && !audio.paused),
      volume: audio?.volume ?? 0,
      src: audio?.currentSrc ?? audio?.src ?? '',
    };
  }

  /**
   * Gradually reduce volume to zero, then pause. No-op if audio is already paused.
   * @param {number} durationMs
   */
  startFadeOut(durationMs) {
    const audio = this.#audio;
    if (!audio || audio.paused) {
      return;
    }

    if (this.#fadeInterval != null) {
      clearInterval(this.#fadeInterval);
      this.#fadeInterval = null;
    }

    const startVolume = audio.volume;
    const stepCount = 10;
    const intervalMs = Math.max(1, durationMs / stepCount);
    let step = 0;

    this.#fadeInterval = setInterval(() => {
      step += 1;
      audio.volume = Math.max(0, startVolume * (1 - step / stepCount));

      if (step >= stepCount) {
        audio.volume = 0;
        audio.pause();
        if (this.#fadeInterval != null) {
          clearInterval(this.#fadeInterval);
          this.#fadeInterval = null;
        }
      }
    }, intervalMs);
  }
}

window.OBS = window.OBS || {};
window.OBS.AudioController = AudioController;