import { preloadStream } from './furumiApi'
import { fmt } from './utils'

const MAX_PLAYBACK_ERROR_SKIPS = 5

/** Seconds from track start above which "previous" rewinds current track instead. */
const PREV_TRACK_REWIND_THRESHOLD_SEC = 3

export interface AudioPlaybackCallbacks {
  onEnded: () => void
  /** Called after a recoverable playback error (to advance queue). */
  onErrorSkip: () => void
  onToast: (msg: string) => void
}

export interface AudioPlaybackHandle {
  loadStreamForTrack(slug: string): Promise<void>
  pauseAndClearSource(): void
  togglePlay(whenNoSource: () => void): void
  seekFromProgressBarClick(e: MouseEvent): void
  toggleMute(): void
  setVolume(percent: number): void
  seekToTime(seconds: number): void
  /** If current time is past the threshold, seeks to 0 and returns true (caller should skip prev-track logic). */
  rewindCurrentTrackIfPastThreshold(): boolean
  dispose(): void
}

function syncVolumeFromStorage(audio: HTMLAudioElement) {
  try {
    const v = window.localStorage.getItem('furumi_vol')
    const volSlider = document.getElementById('volSlider') as HTMLInputElement | null
    if (v !== null && volSlider) {
      audio.volume = Number(v) / 100
      volSlider.value = v
    }
  } catch {
    // ignore
  }
}

export function attachAudioPlayback(
  audio: HTMLAudioElement,
  callbacks: AudioPlaybackCallbacks,
): AudioPlaybackHandle {
  let muted = false
  let playbackErrorSkips = 0

  syncVolumeFromStorage(audio)

  function onTimeUpdate() {
    if (!audio.duration) return
    const fill = document.getElementById('progressFill')
    const timeElapsed = document.getElementById('timeElapsed')
    const timeDuration = document.getElementById('timeDuration')
    if (fill) fill.style.width = `${(audio.currentTime / audio.duration) * 100}%`
    if (timeElapsed) timeElapsed.textContent = fmt(audio.currentTime)
    if (timeDuration) timeDuration.textContent = fmt(audio.duration)
  }

  function setPlayPauseButtonPlaying(playing: boolean) {
    const btn = document.getElementById('btnPlayPause')
    if (btn) btn.innerHTML = playing ? '&#9208;' : '&#9654;'
  }

  function onPlaying() {
    playbackErrorSkips = 0
  }

  function onPlay() {
    setPlayPauseButtonPlaying(true)
  }

  function onPause() {
    setPlayPauseButtonPlaying(false)
  }

  function onError() {
    callbacks.onToast('Playback error')
    if (playbackErrorSkips >= MAX_PLAYBACK_ERROR_SKIPS) return
    playbackErrorSkips += 1
    callbacks.onErrorSkip()
  }

  function onEnded() {
    callbacks.onEnded()
  }

  audio.addEventListener('timeupdate', onTimeUpdate)
  audio.addEventListener('ended', onEnded)
  audio.addEventListener('playing', onPlaying)
  audio.addEventListener('play', onPlay)
  audio.addEventListener('pause', onPause)
  audio.addEventListener('error', onError)

  const progressBar = document.getElementById('progressBar')
  const onProgressClick = (e: Event) => seekFromProgressBarClick(e as MouseEvent)
  progressBar?.addEventListener('click', onProgressClick)

  const volIcon = document.getElementById('volIcon')
  const onVolIconClick = () => toggleMute()
  volIcon?.addEventListener('click', onVolIconClick)

  const volSlider = document.getElementById('volSlider') as HTMLInputElement | null
  const onVolInput = (e: Event) => {
    const v = Number((e.target as HTMLInputElement).value)
    setVolume(v)
  }
  volSlider?.addEventListener('input', onVolInput)

  async function loadStreamForTrack(slug: string) {
    const response = await preloadStream(slug)
    audio.src = URL.createObjectURL(response?.data)
    await audio.play().catch(() => { })
  }

  function pauseAndClearSource() {
    audio.pause()
    audio.src = ''
  }

  function togglePlay(whenNoSource: () => void) {
    if (!audio.src) {
      whenNoSource()
      return
    }
    if (audio.paused) void audio.play()
    else audio.pause()
  }

  function seekFromProgressBarClick(e: MouseEvent) {
    if (!audio.duration) return
    const bar = document.getElementById('progressBar') as HTMLDivElement | null
    if (!bar) return
    const rect = bar.getBoundingClientRect()
    const pct = (e.clientX - rect.left) / rect.width
    audio.currentTime = pct * audio.duration
  }

  function toggleMute() {
    muted = !muted
    audio.muted = muted
    const icon = document.getElementById('volIcon')
    if (icon) icon.innerHTML = muted ? '&#128263;' : '&#128266;'
  }

  function setVolume(percent: number) {
    audio.volume = percent / 100
    const icon = document.getElementById('volIcon')
    if (icon) icon.innerHTML = percent === 0 ? '&#128263;' : '&#128266;'
    window.localStorage.setItem('furumi_vol', String(percent))
  }

  function seekToTime(seconds: number) {
    audio.currentTime = seconds
  }

  function rewindCurrentTrackIfPastThreshold(): boolean {
    if (audio.currentTime > PREV_TRACK_REWIND_THRESHOLD_SEC) {
      audio.currentTime = 0
      return true
    }
    return false
  }

  function dispose() {
    audio.removeEventListener('timeupdate', onTimeUpdate)
    audio.removeEventListener('ended', onEnded)
    audio.removeEventListener('playing', onPlaying)
    audio.removeEventListener('play', onPlay)
    audio.removeEventListener('pause', onPause)
    audio.removeEventListener('error', onError)
    progressBar?.removeEventListener('click', onProgressClick)
    volIcon?.removeEventListener('click', onVolIconClick)
    volSlider?.removeEventListener('input', onVolInput)
    audio.pause()
  }

  return {
    loadStreamForTrack,
    pauseAndClearSource,
    togglePlay,
    seekFromProgressBarClick,
    toggleMute,
    setVolume,
    seekToTime,
    rewindCurrentTrackIfPastThreshold,
    dispose,
  }
}