import { useMemo, useState } from 'react'
import ArrowDownwardIcon from '@mui/icons-material/ArrowDownward'
import ArrowUpwardIcon from '@mui/icons-material/ArrowUpward'
import DeleteOutlineOutlinedIcon from '@mui/icons-material/DeleteOutlineOutlined'
import Box from '@mui/material/Box'
import Button from '@mui/material/Button'
import Dialog from '@mui/material/Dialog'
import DialogActions from '@mui/material/DialogActions'
import DialogContent from '@mui/material/DialogContent'
import DialogTitle from '@mui/material/DialogTitle'
import IconButton from '@mui/material/IconButton'
import Paper from '@mui/material/Paper'
import Stack from '@mui/material/Stack'
import TextField from '@mui/material/TextField'
import Typography from '@mui/material/Typography'
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import { fetchAdminCatalogSlider, putAdminCatalogSlider } from '@/entities/catalog-slider'
import { fetchAdminGallery } from '@/entities/gallery'
import type { GalleryImageItem } from '@/entities/gallery'
import { invalidateQueryKeys } from '@/shared/lib/invalidate-query-keys'

type SlideDraft = { galleryImageId: string; caption: string; textColor: string }

function SliderEditor({
  initialSlides,
  galleryItems,
}: {
  initialSlides: SlideDraft[]
  galleryItems: GalleryImageItem[]
}) {
  const queryClient = useQueryClient()
  const [sliderDraft, setSliderDraft] = useState<SlideDraft[]>(initialSlides)
  const [pickOpen, setPickOpen] = useState(false)

  const usedIds = new Set(sliderDraft.map((s) => s.galleryImageId))
  const pickCandidates = galleryItems.filter((i) => !usedIds.has(i.id) && i.isResized)

  const saveSliderMut = useMutation({
    mutationFn: () =>
      putAdminCatalogSlider({
        slides: sliderDraft.map((s) => ({
          galleryImageId: s.galleryImageId,
          caption: s.caption,
          textColor: s.textColor,
        })),
      }),
    onSuccess: async () => {
      await invalidateQueryKeys(queryClient, [['admin', 'catalog-slider'], ['catalog-slider']])
    },
  })

  const moveSlide = (idx: number, dir: -1 | 1) => {
    const next = idx + dir
    if (next < 0 || next >= sliderDraft.length) return
    setSliderDraft((prev) => {
      const copy = [...prev]
      const t = copy[idx]!
      copy[idx] = copy[next]!
      copy[next] = t
      return copy
    })
  }

  const updateDraft = (idx: number, patch: Partial<SlideDraft>) => {
    setSliderDraft((prev) => {
      const copy = [...prev]
      copy[idx] = { ...copy[idx]!, ...patch }
      return copy
    })
  }

  return (
    <>
      <Paper variant="outlined" sx={{ p: 2, borderRadius: 2 }}>
        <Stack spacing={1.5} sx={{ mb: 2 }}>
          {sliderDraft.length === 0 && (
            <Typography color="text.secondary">Нет слайдов. Добавьте изображения из галереи.</Typography>
          )}

          {sliderDraft.map((row, idx) => {
            const img = galleryItems.find((g) => g.id === row.galleryImageId)
            return (
              <Stack
                key={`${row.galleryImageId}-${idx}`}
                direction={{ xs: 'column', sm: 'row' }}
                spacing={1.5}
                sx={{ alignItems: { sm: 'flex-start' } }}
              >
                <Box
                  sx={{
                    width: 100,
                    height: 100,
                    flexShrink: 0,
                    borderRadius: 1,
                    overflow: 'hidden',
                    border: 1,
                    borderColor: 'divider',
                  }}
                >
                  <Box
                    component="img"
                    src={img?.url ?? ''}
                    alt=""
                    sx={{ width: '100%', height: '100%', objectFit: 'cover', display: 'block' }}
                  />
                </Box>
                <Stack spacing={1.5} sx={{ flex: 1, minWidth: 0 }}>
                  <TextField
                    label="Подпись на слайде"
                    fullWidth
                    multiline
                    minRows={2}
                    value={row.caption}
                    onChange={(e) => updateDraft(idx, { caption: e.target.value })}
                  />
                  <TextField
                    label="Цвет текста"
                    type="color"
                    value={row.textColor}
                    onChange={(e) => updateDraft(idx, { textColor: e.target.value })}
                    sx={{ width: 80 }}
                    slotProps={{ inputLabel: { shrink: true } }}
                  />
                </Stack>
                <Stack direction="row" spacing={0.5} sx={{ alignSelf: 'flex-start' }}>
                  <IconButton size="small" aria-label="Выше" onClick={() => moveSlide(idx, -1)} disabled={idx === 0}>
                    <ArrowUpwardIcon fontSize="small" />
                  </IconButton>
                  <IconButton
                    size="small"
                    aria-label="Ниже"
                    onClick={() => moveSlide(idx, 1)}
                    disabled={idx >= sliderDraft.length - 1}
                  >
                    <ArrowDownwardIcon fontSize="small" />
                  </IconButton>
                  <IconButton
                    size="small"
                    color="error"
                    aria-label="Убрать из слайдера"
                    onClick={() => setSliderDraft((prev) => prev.filter((_, i) => i !== idx))}
                  >
                    <DeleteOutlineOutlinedIcon fontSize="small" />
                  </IconButton>
                </Stack>
              </Stack>
            )
          })}
        </Stack>

        <Stack direction="row" spacing={2} sx={{ flexWrap: 'wrap', alignItems: 'center' }}>
          <Button variant="outlined" disabled={pickCandidates.length === 0} onClick={() => setPickOpen(true)}>
            Добавить слайд из галереи
          </Button>
          <Button variant="contained" disabled={saveSliderMut.isPending} onClick={() => saveSliderMut.mutate()}>
            Сохранить слайдер
          </Button>
          {saveSliderMut.isError && (
            <Typography color="error">
              {saveSliderMut.error instanceof Error ? saveSliderMut.error.message : 'Ошибка сохранения'}
            </Typography>
          )}
        </Stack>
      </Paper>

      <Dialog open={pickOpen} onClose={() => setPickOpen(false)} fullWidth maxWidth="sm">
        <DialogTitle>Выберите изображение</DialogTitle>
        <DialogContent dividers>
          {pickCandidates.length === 0 ? (
            <Typography color="text.secondary">Нет доступных файлов (все уже в слайдере или галерея пуста).</Typography>
          ) : (
            <Box
              sx={{
                display: 'grid',
                gridTemplateColumns: 'repeat(auto-fill, minmax(120px, 1fr))',
                gap: 1.5,
                pt: 1,
              }}
            >
              {pickCandidates.map((item) => (
                <Button
                  key={item.id}
                  sx={{ p: 0, minWidth: 0, display: 'block', borderRadius: 1, overflow: 'hidden' }}
                  onClick={() => {
                    setSliderDraft((prev) => [...prev, { galleryImageId: item.id, caption: '', textColor: '#ffffff' }])
                    setPickOpen(false)
                  }}
                >
                  <Box
                    component="img"
                    src={item.url}
                    alt=""
                    sx={{ width: '100%', aspectRatio: '1', objectFit: 'cover', display: 'block' }}
                  />
                </Button>
              ))}
            </Box>
          )}
        </DialogContent>
        <DialogActions>
          <Button onClick={() => setPickOpen(false)}>Закрыть</Button>
        </DialogActions>
      </Dialog>
    </>
  )
}

export function AdminSliderPage() {
  const sliderQuery = useQuery({
    queryKey: ['admin', 'catalog-slider'],
    queryFn: fetchAdminCatalogSlider,
  })

  const galleryQuery = useQuery({
    queryKey: ['admin', 'gallery'],
    queryFn: fetchAdminGallery,
  })

  const galleryItems: GalleryImageItem[] = galleryQuery.data?.items ?? []

  const initialSlides = useMemo<SlideDraft[]>(() => {
    if (!sliderQuery.isSuccess) return []
    return sliderQuery.data.slides.map((s) => ({
      galleryImageId: s.galleryImageId,
      caption: s.caption,
      textColor: s.textColor || '#ffffff',
    }))
  }, [sliderQuery.isSuccess, sliderQuery.data?.slides])

  if (sliderQuery.isLoading || galleryQuery.isLoading) {
    return <Typography color="text.secondary">Загрузка…</Typography>
  }

  if (sliderQuery.isError) {
    return <Typography color="error">Не удалось загрузить слайдер.</Typography>
  }

  return (
    <Box>
      <Typography variant="h4" gutterBottom>
        Слайдер
      </Typography>
      <Typography variant="body2" color="text.secondary" sx={{ mb: 2 }}>
        Изображения для карусели на главной странице. Сначала загрузите фото в Галерею и обработайте их (Resize), затем
        добавьте в слайдер. Порядок строк = порядок показа.
      </Typography>

      <SliderEditor key={sliderQuery.dataUpdatedAt} initialSlides={initialSlides} galleryItems={galleryItems} />
    </Box>
  )
}