import { useEffect, useState } from 'react'
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import type { FeedVideoDto } from '../api/client'
import { downloadVideo, getDownloadStatus } from '../api/client'

const ACTIVE_STATUSES = ['queued', 'downloading', 'postprocessing']

const STATUS_LABELS: Record<string, string> = {
  queued: 'В очереди...',
  postprocessing: 'Обработка...',
}

interface Props {
  video: FeedVideoDto
}

function DownloadButton({ video }: Props) {
  const queryClient = useQueryClient()
  const [polling, setPolling] = useState(ACTIVE_STATUSES.includes(video.local.status))

  const statusQuery = useQuery({
    queryKey: ['download-status', video.youtube_video_id],
    queryFn: () => getDownloadStatus(video.youtube_video_id),
    enabled: polling,
    refetchInterval: (query) => (query.state.data && ACTIVE_STATUSES.includes(query.state.data.status) ? 2000 : false),
    initialData: polling
      ? {
          status: video.local.status,
          progress_percent: video.local.progress_percent,
          media_url: video.local.media_url,
          error_message: null,
        }
      : undefined,
  })

  const downloadMutation = useMutation({
    mutationFn: () => downloadVideo(video.youtube_video_id),
    onSuccess: (data) => {
      queryClient.setQueryData(['download-status', video.youtube_video_id], data)
      setPolling(true)
    },
  })

  const current = polling ? statusQuery.data : undefined
  const status = current?.status ?? video.local.status
  const percent = current?.progress_percent ?? video.local.progress_percent

  useEffect(() => {
    if (current && !ACTIVE_STATUSES.includes(current.status)) {
      setPolling(false)
      if (current.status === 'completed' || current.status === 'failed') {
        queryClient.invalidateQueries({ queryKey: ['feed'] })
      }
    }
  }, [current?.status, queryClient])

  if (status === 'completed') {
    return <span className="download-badge completed">✓ На сервере</span>
  }

  if (status === 'downloading') {
    return <span className="download-badge">{percent ?? 0}%</span>
  }

  if (status === 'queued' || status === 'postprocessing') {
    return <span className="download-badge">{STATUS_LABELS[status]}</span>
  }

  if (status === 'failed') {
    return (
      <span className="download-error">
        <span className="download-badge error">Ошибка</span>
        <button onClick={() => downloadMutation.mutate()} disabled={downloadMutation.isPending}>
          Повторить
        </button>
      </span>
    )
  }

  return (
    <button onClick={() => downloadMutation.mutate()} disabled={downloadMutation.isPending}>
      ⬇ Скачать
    </button>
  )
}

export default DownloadButton