import { useEffect, useRef, useState } from 'react'

// Nur eine Stimme gleichzeitig im Feed
let currentAudio = null

// Reines Vorlesen wird gedrosselt (User-Wunsch). Pitch bleibt durch den
// Browser-Default `preservesPitch` erhalten.
const PLAYBACK_RATE = 0.7

export default function usePairAudio(url) {
  const audioRef = useRef(null)
  const rafRef = useRef(null)
  const failedRef = useRef(false)
  const [playing, setPlaying] = useState(false)
  const [currentTime, setCurrentTime] = useState(0)
  const [failed, setFailed] = useState(false)
  const markFailed = () => { failedRef.current = true; setFailed(true) }

  useEffect(() => {
    if (!url) { audioRef.current = null; return }
    failedRef.current = false
    setFailed(false)
    const audio = new Audio(url)
    audio.preload = 'auto'
    audio.playbackRate = PLAYBACK_RATE

    // currentTime ~30fps mitschreiben, solange das Audio läuft (für Karaoke-Sync).
    let lastTick = 0
    const tick = (ts) => {
      if (ts - lastTick >= 33) { lastTick = ts; setCurrentTime(audio.currentTime) }
      rafRef.current = requestAnimationFrame(tick)
    }
    const stopLoop = () => {
      if (rafRef.current) { cancelAnimationFrame(rafRef.current); rafRef.current = null }
    }

    const onPlay  = () => { setPlaying(true); stopLoop(); rafRef.current = requestAnimationFrame(tick) }
    const onStop  = () => { setPlaying(false); stopLoop(); setCurrentTime(audio.currentTime) }
    const onEnded = () => { setPlaying(false); stopLoop(); setCurrentTime(0) }
    // Netz-/Decode-Fehler eines vorhandenen Files → File gilt als nicht abspielbar,
    // damit play() den TTS-Fallback der Karte greifen lässt.
    const onError = () => { setPlaying(false); stopLoop(); markFailed() }
    audio.addEventListener('play', onPlay)
    audio.addEventListener('pause', onStop)
    audio.addEventListener('ended', onEnded)
    audio.addEventListener('error', onError)
    audioRef.current = audio
    return () => {
      stopLoop()
      audio.pause()
      audio.removeEventListener('play', onPlay)
      audio.removeEventListener('pause', onStop)
      audio.removeEventListener('ended', onEnded)
      audio.removeEventListener('error', onError)
      if (currentAudio === audio) currentAudio = null
      audio.src = ''
      audioRef.current = null
    }
  }, [url])

  function play() {
    const audio = audioRef.current
    if (!audio || failedRef.current) return false
    if (currentAudio && currentAudio !== audio) currentAudio.pause()
    currentAudio = audio
    audio.currentTime = 0
    audio.playbackRate = PLAYBACK_RATE
    // AbortError = von einem pause() unterbrochen (harmlos); echte Quell-/Decode-Fehler
    // markieren das File als nicht abspielbar → Karte fällt auf TTS zurück.
    audio.play().catch((err) => { if (err?.name !== 'AbortError') markFailed() })
    return true
  }

  return { play, playing, currentTime, failed }
}