import { computed, onUnmounted, ref } from 'vue'
import { createTtsTask, getTtsTask, getTtsTaskBySource } from '../services/tts.js'
import analytics from '../services/analytics.js'

const readResponseData = (response) => {
  if (!response) return null
  if (Object.prototype.hasOwnProperty.call(response, 'data')) {
    return response.data ?? null
  }
  return response
}

export const useTtsPlayer = ({ pagePath = '', sourceType = 'epic_script' } = {}) => {
  const task = ref(null)
  const loading = ref(false)
  const playing = ref(false)
  const statusText = ref('')
  let audio = null
  let timer = null
  let prewarmPromise = null
  let prewarmSourceId = ''

  const buttonText = computed(() => {
    if (loading.value) return '正在生成朗读'
    if (task.value?.status === 'success') return playing.value ? '暂停朗读' : '播放朗读'
    if (task.value?.status === 'failed') return '重试朗读'
    return '语音播放'
  })

  const clearTimer = () => {
    if (timer) clearInterval(timer)
    timer = null
  }

  const stopAudio = () => {
    if (!audio) return
    audio.stop()
    audio.destroy()
    audio = null
    playing.value = false
  }

  const setTask = (nextTask) => {
    task.value = nextTask
    if (audio && nextTask?.audioUrl && audio.src !== nextTask.audioUrl) {
      stopAudio()
    }
  }

  const track = (eventName, sourceId, payload = {}) => {
    analytics.track(eventName, {
      source_id: sourceId || '',
      task_id: task.value?.id || '',
      ...payload
    }, { eventType: 'tts', pagePath })
  }

  const markFailed = (message) => {
    loading.value = false
    statusText.value = message || '朗读暂时不可用'
    uni.showToast({ title: statusText.value, icon: 'none' })
  }

  const pollTask = (taskId, sourceId) => {
    clearTimer()
    timer = setInterval(async () => {
      try {
        const response = await getTtsTask(taskId)
        const nextTask = readResponseData(response)
        setTask(nextTask)

        if (nextTask?.status === 'success') {
          loading.value = false
          statusText.value = ''
          clearTimer()
          track('script_tts_success', sourceId, { task_id: nextTask.id })
          play(sourceId)
          return
        }

        if (nextTask?.status === 'failed') {
          clearTimer()
          track('script_tts_error', sourceId, { error: nextTask.errorMessage || '' })
          markFailed(nextTask.errorMessage || '朗读生成失败')
        }
      } catch (error) {
        clearTimer()
        track('script_tts_error', sourceId, { error: error?.message || error?.errMsg || 'poll failed' })
        markFailed('朗读状态获取失败')
      }
    }, 2500)
  }

  const play = (sourceId) => {
    if (!task.value?.audioUrl) return

    if (!audio) {
      audio = uni.createInnerAudioContext()
      audio.src = task.value.audioUrl
      audio.autoplay = false

      audio.onPlay(() => {
        playing.value = true
        track('script_tts_play', sourceId)
      })

      audio.onPause(() => {
        playing.value = false
        track('script_tts_pause', sourceId)
      })

      audio.onEnded(() => {
        playing.value = false
        track('script_tts_complete', sourceId)
      })

      audio.onError((error) => {
        playing.value = false
        track('script_tts_error', sourceId, { error: error?.errMsg || 'play failed' })
        markFailed('音频播放失败')
      })
    }

    if (playing.value) {
      audio.pause()
    } else {
      audio.play()
    }
  }

  const createAndPoll = async (sourceId) => {
    loading.value = true
    statusText.value = ''
    track('script_tts_request', sourceId)

    try {
      const response = await createTtsTask({ sourceType, sourceId })
      const nextTask = readResponseData(response)
      setTask(nextTask)

      if (nextTask?.status === 'success') {
        loading.value = false
        track('script_tts_success', sourceId, { task_id: nextTask.id })
        play(sourceId)
        return
      }

      if (nextTask?.status === 'failed') {
        track('script_tts_error', sourceId, { error: nextTask.errorMessage || '' })
        markFailed(nextTask.errorMessage || '朗读生成失败')
        return
      }

      if (nextTask?.id) {
        pollTask(nextTask.id, sourceId)
        return
      }

      markFailed('朗读任务创建失败')
    } catch (error) {
      track('script_tts_error', sourceId, { error: error?.message || error?.errMsg || 'create failed' })
      markFailed(error?.message || '朗读任务创建失败')
    }
  }

  const prewarmSource = async (sourceId) => {
    if (!sourceId) return null
    if (task.value?.status === 'success' && task.value?.sourceId === sourceId) {
      return task.value
    }
    if (prewarmPromise && prewarmSourceId === sourceId) {
      return prewarmPromise
    }

    prewarmSourceId = sourceId
    prewarmPromise = (async () => {
      try {
        const existingResponse = await getTtsTaskBySource({ sourceType, sourceId })
        const existingTask = readResponseData(existingResponse)
        if (existingTask?.id) {
          setTask(existingTask)
        }
        if (existingTask?.status === 'success' || existingTask?.status === 'pending' || existingTask?.status === 'processing') {
          return existingTask
        }
      } catch (error) {
        // Old scripts may not have a task yet; create one silently below.
      }

      try {
        const createResponse = await createTtsTask({ sourceType, sourceId })
        const nextTask = readResponseData(createResponse)
        if (nextTask?.id) {
          setTask(nextTask)
        }
        return nextTask
      } catch (error) {
        track('script_tts_error', sourceId, { error: error?.message || error?.errMsg || 'prewarm failed' })
        return null
      } finally {
        prewarmPromise = null
        prewarmSourceId = ''
      }
    })()

    return prewarmPromise
  }

  const playSource = async (sourceId) => {
    if (!sourceId) {
      uni.showToast({ title: '生成保存后可播放', icon: 'none' })
      return
    }
    if (loading.value) return

    if (prewarmPromise && prewarmSourceId === sourceId) {
      const warmedTask = await prewarmPromise
      if (warmedTask?.status === 'success') {
        setTask(warmedTask)
        play(sourceId)
        return
      }
      if ((warmedTask?.status === 'pending' || warmedTask?.status === 'processing') && warmedTask?.id) {
        setTask(warmedTask)
        loading.value = true
        pollTask(warmedTask.id, sourceId)
        return
      }
    }

    if (task.value?.status === 'success') {
      play(sourceId)
      return
    }

    try {
      const response = await getTtsTaskBySource({ sourceType, sourceId })
      const existingTask = readResponseData(response)
      setTask(existingTask)

      if (existingTask?.status === 'success') {
        play(sourceId)
        return
      }

      if (existingTask?.status === 'pending' || existingTask?.status === 'processing') {
        loading.value = true
        pollTask(existingTask.id, sourceId)
        return
      }
    } catch (error) {
      // Missing existing task should fall through and create a new one.
    }

    await createAndPoll(sourceId)
  }

  const reset = () => {
    clearTimer()
    stopAudio()
    setTask(null)
    statusText.value = ''
    loading.value = false
    prewarmPromise = null
    prewarmSourceId = ''
  }

  onUnmounted(reset)

  return {
    task,
    loading,
    playing,
    statusText,
    buttonText,
    prewarmSource,
    playSource,
    reset
  }
}

export default useTtsPlayer