'use client'

import { useState, useCallback, useRef, useEffect } from 'react'
import { Language, SlideId } from '../types'
import { PresenterState } from '../presenter/types'
import { PRESENTER_SCRIPT } from '../presenter/presenter-script'
import { SLIDE_ORDER } from './useSlideNavigation'

interface UsePresenterModeConfig {
  goToSlide: (index: number) => void
  currentSlide: number
  totalSlides: number
  language: Language
  ttsEnabled?: boolean // default true
}

interface UsePresenterModeReturn {
  state: PresenterState
  currentParagraph: number
  start: () => void
  stop: () => void
  pause: () => void
  resume: () => void
  skipSlide: () => void
  toggle: () => void
  displayText: string
  progress: number
  isSpeaking: boolean
  ttsAvailable: boolean
  ttsEnabled: boolean
  setTtsEnabled: (enabled: boolean) => void
}

// Client-side audio cache: text key → blob URL
const audioCache = new Map<string, string>()

function cacheKey(text: string, lang: string): string {
  // Simple string hash — no crypto.subtle needed (works on HTTP too)
  let hash = 0
  const str = text + '|' + lang
  for (let i = 0; i < str.length; i++) {
    hash = ((hash << 5) - hash + str.charCodeAt(i)) | 0
  }
  return 'tts_' + (hash >>> 0).toString(36)
}

export function usePresenterMode({
  goToSlide,
  currentSlide,
  totalSlides,
  language,
  ttsEnabled: initialTtsEnabled = true,
}: UsePresenterModeConfig): UsePresenterModeReturn {
  const [state, setState] = useState<PresenterState>('idle')
  const [currentParagraph, setCurrentParagraph] = useState(0)
  const [displayText, setDisplayText] = useState('')
  const [isSpeaking, setIsSpeaking] = useState(false)
  const [ttsEnabled, setTtsEnabled] = useState(initialTtsEnabled)
  const [ttsAvailable, setTtsAvailable] = useState(false)
  const timerRef = useRef<NodeJS.Timeout | null>(null)
  const slideIndexRef = useRef(currentSlide)
  const paragraphIndexRef = useRef(0)
  const stateRef = useRef<PresenterState>('idle')
  const audioRef = useRef<HTMLAudioElement | null>(null)
  const abortRef = useRef<AbortController | null>(null)
  const audioUnlockedRef = useRef(false)

  // Refs for recursive functions to avoid circular useCallback dependencies
  const advanceRef = useRef<() => void>(() => {})
  const speakAndAdvanceRef = useRef<(text: string, pauseAfter: number, onDone: () => void) => void>(() => {})

  // Unlock browser audio playback — must be called from a user gesture (click)
  const unlockAudio = useCallback(() => {
    if (audioUnlockedRef.current) return
    try {
      // Create and play a silent audio to unlock the Audio API
      const ctx = new (window.AudioContext || (window as any).webkitAudioContext)()
      const buffer = ctx.createBuffer(1, 1, 22050)
      const source = ctx.createBufferSource()
      source.buffer = buffer
      source.connect(ctx.destination)
      source.start(0)
      audioUnlockedRef.current = true
      console.log('Audio playback unlocked')
    } catch (e) {
      console.warn('Audio unlock failed:', e)
    }
  }, [])

  // Check TTS service availability on mount
  useEffect(() => {
    fetch('/api/presenter/tts', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ text: 'Test', language: 'de' }),
      signal: AbortSignal.timeout(5000),
    })
      .then(res => {
        setTtsAvailable(res.ok)
        if (res.ok) console.log('Piper TTS available')
        else console.warn('Piper TTS not available:', res.status)
      })
      .catch(() => {
        setTtsAvailable(false)
        console.warn('Piper TTS service not reachable')
      })
  }, [])

  const cancelSpeech = useCallback(() => {
    if (audioRef.current) {
      audioRef.current.pause()
      audioRef.current.currentTime = 0
      audioRef.current = null
    }
    if (abortRef.current) {
      abortRef.current.abort()
      abortRef.current = null
    }
    setIsSpeaking(false)
  }, [])

  // Keep refs in sync
  useEffect(() => { slideIndexRef.current = currentSlide }, [currentSlide])
  useEffect(() => { stateRef.current = state }, [state])

  const clearTimer = useCallback(() => {
    if (timerRef.current) {
      clearTimeout(timerRef.current)
      timerRef.current = null
    }
  }, [])

  const getScriptForIndex = useCallback((index: number) => {
    const slideId = SLIDE_ORDER[index]
    return PRESENTER_SCRIPT.find(s => s.slideId === slideId)
  }, [])

  const showParagraph = useCallback((slideIdx: number, paraIdx: number) => {
    const script = getScriptForIndex(slideIdx)
    if (!script || paraIdx >= script.paragraphs.length) return null

    const para = script.paragraphs[paraIdx]
    const text = language === 'de' ? para.text_de : para.text_en
    setDisplayText(text)
    setCurrentParagraph(paraIdx)
    paragraphIndexRef.current = paraIdx
    return para
  }, [language, getScriptForIndex])

  // Update speakAndAdvance ref whenever dependencies change
  useEffect(() => {
    speakAndAdvanceRef.current = (text: string, pauseAfter: number, onDone: () => void) => {
      if (!ttsAvailable || !ttsEnabled) {
        // No TTS — use word-count-based timer
        const wordCount = text.split(/\s+/).length
        const readingTime = Math.max(wordCount * 150, 2000)
        timerRef.current = setTimeout(onDone, readingTime + pauseAfter)
        return
      }

      // Piper TTS via API
      setIsSpeaking(true)
      const controller = new AbortController()
      abortRef.current = controller

      const playAudio = async () => {
        try {
          const key = cacheKey(text, language)
          let blobUrl = audioCache.get(key)

          if (!blobUrl) {
            console.log('[TTS] Fetching audio for:', text.slice(0, 50) + '...')
            const res = await fetch('/api/presenter/tts', {
              method: 'POST',
              headers: { 'Content-Type': 'application/json' },
              body: JSON.stringify({ text, language }),
              signal: controller.signal,
            })

            if (!res.ok) throw new Error(`TTS error: ${res.status}`)

            const blob = await res.blob()
            console.log('[TTS] Audio received:', blob.size, 'bytes')
            blobUrl = URL.createObjectURL(blob)
            audioCache.set(key, blobUrl)
          } else {
            console.log('[TTS] Cache hit for:', text.slice(0, 50) + '...')
          }

          if (controller.signal.aborted) return

          const audio = new Audio(blobUrl)
          audioRef.current = audio

          audio.onended = () => {
            console.log('[TTS] Audio playback ended')
            setIsSpeaking(false)
            audioRef.current = null
            if (pauseAfter > 0) {
              timerRef.current = setTimeout(onDone, pauseAfter)
            } else {
              onDone()
            }
          }

          audio.onerror = (e) => {
            console.warn('[TTS] Audio playback error:', e)
            setIsSpeaking(false)
            audioRef.current = null
            const wordCount = text.split(/\s+/).length
            const readingTime = Math.max(wordCount * 150, 2000)
            timerRef.current = setTimeout(onDone, readingTime + pauseAfter)
          }

          await audio.play()
          console.log('[TTS] Audio playing')
        } catch (err: any) {
          if (err.name === 'AbortError') return
          console.warn('[TTS] Error:', err.name, err.message)
          setIsSpeaking(false)
          const wordCount = text.split(/\s+/).length
          const readingTime = Math.max(wordCount * 150, 2000)
          timerRef.current = setTimeout(onDone, readingTime + pauseAfter)
        }
      }

      playAudio()
    }
  }, [ttsAvailable, ttsEnabled, language])

  // Update advancePresentation ref whenever dependencies change
  useEffect(() => {
    advanceRef.current = () => {
      if (stateRef.current !== 'presenting') return

      const slideIdx = slideIndexRef.current
      const script = getScriptForIndex(slideIdx)

      if (!script) {
        if (slideIdx < totalSlides - 1) {
          goToSlide(slideIdx + 1)
          paragraphIndexRef.current = 0
          timerRef.current = setTimeout(() => advanceRef.current(), 2000)
        } else {
          cancelSpeech()
          setState('idle')
          setDisplayText('')
        }
        return
      }

      const nextPara = paragraphIndexRef.current + 1

      if (nextPara < script.paragraphs.length) {
        const para = showParagraph(slideIdx, nextPara)
        if (para) {
          const text = language === 'de' ? para.text_de : para.text_en
          speakAndAdvanceRef.current(text, para.pause_after, () => advanceRef.current())
        }
      } else {
        // All paragraphs done — transition hint then next slide
        const hint = language === 'de'
          ? (script.transition_hint_de || '')
          : (script.transition_hint_en || '')

        const goNext = () => {
          if (slideIdx < totalSlides - 1) {
            timerRef.current = setTimeout(() => {
              if (stateRef.current !== 'presenting') return
              goToSlide(slideIdx + 1)
              paragraphIndexRef.current = -1

              timerRef.current = setTimeout(() => {
                if (stateRef.current !== 'presenting') return
                const nextScript = getScriptForIndex(slideIdx + 1)
                if (nextScript && nextScript.paragraphs.length > 0) {
                  const para = showParagraph(slideIdx + 1, 0)
                  if (para) {
                    const text = language === 'de' ? para.text_de : para.text_en
                    speakAndAdvanceRef.current(text, para.pause_after, () => advanceRef.current())
                  }
                } else {
                  advanceRef.current()
                }
              }, 1500)
            }, 1000)
          } else {
            timerRef.current = setTimeout(() => {
              cancelSpeech()
              setState('idle')
              setDisplayText('')
            }, 3000)
          }
        }

        if (hint) {
          setDisplayText(hint)
          speakAndAdvanceRef.current(hint, 0, () => {
            if (stateRef.current !== 'presenting') return
            goNext()
          })
        } else {
          goNext()
        }
      }
    }
  }, [language, totalSlides, goToSlide, getScriptForIndex, showParagraph, cancelSpeech])

  const start = useCallback(() => {
    // Unlock audio playback immediately in user gesture context
    unlockAudio()

    clearTimer()
    cancelSpeech()
    setState('presenting')
    stateRef.current = 'presenting'

    const slideIdx = slideIndexRef.current
    const script = getScriptForIndex(slideIdx)

    if (script && script.paragraphs.length > 0) {
      const para = showParagraph(slideIdx, 0)
      if (para) {
        const text = language === 'de' ? para.text_de : para.text_en
        speakAndAdvanceRef.current(text, para.pause_after, () => advanceRef.current())
      }
    } else {
      timerRef.current = setTimeout(() => advanceRef.current(), 1000)
    }
  }, [unlockAudio, clearTimer, cancelSpeech, language, getScriptForIndex, showParagraph])

  const stop = useCallback(() => {
    clearTimer()
    cancelSpeech()
    setState('idle')
    setDisplayText('')
    setCurrentParagraph(0)
    paragraphIndexRef.current = 0
  }, [clearTimer, cancelSpeech])

  const pause = useCallback(() => {
    clearTimer()
    cancelSpeech()
    setState('paused')
  }, [clearTimer, cancelSpeech])

  const resume = useCallback(() => {
    setState('resuming')
    stateRef.current = 'resuming'
    timerRef.current = setTimeout(() => {
      setState('presenting')
      stateRef.current = 'presenting' // Sync ref immediately before calling advance
      advanceRef.current()
    }, 2000)
  }, [])

  const skipSlide = useCallback(() => {
    clearTimer()
    cancelSpeech()
    const nextIdx = slideIndexRef.current + 1
    if (nextIdx < totalSlides) {
      goToSlide(nextIdx)
      paragraphIndexRef.current = -1

      if (stateRef.current === 'presenting') {
        timerRef.current = setTimeout(() => {
          const script = getScriptForIndex(nextIdx)
          if (script && script.paragraphs.length > 0) {
            const para = showParagraph(nextIdx, 0)
            if (para) {
              const text = language === 'de' ? para.text_de : para.text_en
              speakAndAdvanceRef.current(text, para.pause_after, () => advanceRef.current())
            }
          }
        }, 1500)
      }
    }
  }, [clearTimer, cancelSpeech, totalSlides, goToSlide, language, getScriptForIndex, showParagraph])

  const toggle = useCallback(() => {
    unlockAudio()
    if (stateRef.current === 'idle') {
      start()
    } else {
      stop()
    }
  }, [unlockAudio, start, stop])

  // Calculate overall progress
  const progress = (() => {
    if (state === 'idle') return 0
    const totalScripts = PRESENTER_SCRIPT.length
    const currentScriptIdx = PRESENTER_SCRIPT.findIndex(s => s.slideId === SLIDE_ORDER[currentSlide])
    if (currentScriptIdx < 0) return (currentSlide / totalSlides) * 100

    const script = PRESENTER_SCRIPT[currentScriptIdx]
    const slideProgress = script.paragraphs.length > 0
      ? currentParagraph / script.paragraphs.length
      : 0
    return ((currentScriptIdx + slideProgress) / totalScripts) * 100
  })()

  // Cleanup on unmount
  useEffect(() => {
    return () => {
      clearTimer()
      cancelSpeech()
    }
  }, [clearTimer, cancelSpeech])

  return {
    state,
    currentParagraph,
    start,
    stop,
    pause,
    resume,
    skipSlide,
    toggle,
    displayText,
    progress,
    isSpeaking,
    ttsAvailable,
    ttsEnabled,
    setTtsEnabled,
  }
}