import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
import { useDropzone } from 'react-dropzone';
import {
  Box,
  Button,
  Card,
  CardActionArea,
  CardContent,
  CardMedia,
  ClickAwayListener,
  Divider,
  Grid,
  LinearProgress,
  Paper,
  Stack,
  TextField,
  Typography,
} from '@mui/material';
import { useNavigate } from 'react-router-dom';
import { useAppStore } from '../store/useAppStore';

const dropzoneStyle = {
  border: '2px dashed rgba(108, 155, 207, 0.7)',
  borderRadius: 12,
  padding: '32px',
  textAlign: 'center',
  backgroundColor: 'rgba(108, 155, 207, 0.08)',
  cursor: 'pointer',
};

const UploadStep = () => {
  const navigate = useNavigate();
  const uploadedImages = useAppStore((state) => state.uploadedImages);
  const setUploadedImages = useAppStore((state) => state.setUploadedImages);
  const resetFromStep = useAppStore((state) => state.resetFromStep);
  const coverImageId = useAppStore((state) => state.coverImageId);
  const setCoverImageId = useAppStore((state) => state.setCoverImageId);
  const bookTitle = useAppStore((state) => state.bookTitle);
  const setBookTitle = useAppStore((state) => state.setBookTitle);
  const bookMetadata = useAppStore((state) => state.bookMetadata);
  const setBookMetadata = useAppStore((state) => state.setBookMetadata);
  const [searchResults, setSearchResults] = useState([]);
  const [searching, setSearching] = useState(false);
  const [searchError, setSearchError] = useState(null);
  const [selectedBookId, setSelectedBookId] = useState(bookMetadata?.id || null);
  const skipSearchRef = useRef(false);
  const [showResults, setShowResults] = useState(false);

  const onDrop = useCallback(
    (acceptedFiles) => {
      if (!acceptedFiles.length) return;
      const preservedMetadata = bookMetadata;
      const preservedTitle = bookTitle;
      resetFromStep('upload');
      if (preservedMetadata) {
        skipSearchRef.current = true;
        setBookMetadata(preservedMetadata);
        setBookTitle(preservedTitle || preservedMetadata.title || '');
      } else if (preservedTitle?.trim()) {
        skipSearchRef.current = true;
        setBookTitle(preservedTitle);
      }
      const mapped = acceptedFiles.map((file, index) => ({
        id: crypto.randomUUID(),
        file,
        previewUrl: URL.createObjectURL(file),
        order: uploadedImages.length + index,
        filename: file.name,
      }));
      setUploadedImages([...uploadedImages, ...mapped]);
    },
    [
      bookMetadata,
      bookTitle,
      resetFromStep,
      setBookMetadata,
      setBookTitle,
      setUploadedImages,
      uploadedImages,
    ],
  );

  const handleCoverToggle = (imageId) => {
    const nextId = coverImageId === imageId ? null : imageId;
    setCoverImageId(nextId);
  };

  useEffect(() => {
    setSelectedBookId(bookMetadata?.id || null);
  }, [bookMetadata]);

  const normalizeVolume = useCallback((volume) => {
    const info = volume?.volumeInfo || {};
    const identifiers = Array.isArray(info.industryIdentifiers)
      ? info.industryIdentifiers.map((identifier) => ({
          type: identifier?.type,
          identifier: identifier?.identifier,
        }))
      : [];
    const thumbnail =
      info.imageLinks?.thumbnail?.replace('http://', 'https://') ||
      info.imageLinks?.smallThumbnail?.replace('http://', 'https://') ||
      null;
    return {
      id: volume.id,
      title: info.title || 'İsimsiz kitap',
      subtitle: info.subtitle || '',
      authors: info.authors || [],
      publisher: info.publisher || '',
      publishedDate: info.publishedDate || '',
      description: info.description || '',
      pageCount: info.pageCount || null,
      categories: info.categories || [],
      averageRating: info.averageRating || null,
      ratingsCount: info.ratingsCount || null,
      language: info.language || '',
      infoLink: info.infoLink || info.previewLink || '',
      identifiers,
      thumbnail,
    };
  }, []);

  useEffect(() => {
    if (skipSearchRef.current) {
      skipSearchRef.current = false;
      return;
    }
    const query = bookTitle?.trim();
    if (!query) {
      setSearchResults([]);
      setSearchError(null);
      setSearching(false);
      setShowResults(false);
      return;
    }
    const controller = new AbortController();
    const timer = setTimeout(async () => {
      setSearching(true);
      setSearchError(null);
      try {
        const response = await fetch(
          `https://www.googleapis.com/books/v1/volumes?q=intitle:${encodeURIComponent(query)}&maxResults=5&printType=books`,
          { signal: controller.signal },
        );
        if (!response.ok) {
          throw new Error('Google Books sonuçları alınamadı.');
        }
        const payload = await response.json();
        const items = Array.isArray(payload.items) ? payload.items : [];
        const normalized = items.map((item) => normalizeVolume(item));
        setSearchResults(normalized);
        setShowResults(Boolean(normalized.length));
        if (!normalized.length) {
          setSearchError('Bu başlıkla eşleşen bir kayıt bulunamadı.');
        }
      } catch (error) {
        if (controller.signal.aborted) return;
        setSearchResults([]);
        setSearchError(error.message || 'Google Books araması başarısız oldu.');
        setShowResults(false);
      } finally {
        if (!controller.signal.aborted) {
          setSearching(false);
        }
      }
    }, 500);
    return () => {
      clearTimeout(timer);
      controller.abort();
    };
  }, [bookTitle, normalizeVolume]);

  const { getRootProps, getInputProps, isDragActive } = useDropzone({
    onDrop,
    accept: {
      'image/png': ['.png'],
      'image/jpeg': ['.jpg', '.jpeg'],
    },
    multiple: true,
  });

  const handleTitleChange = (event) => {
    const value = event.target.value;
    setBookTitle(value);
    if (!value?.trim()) {
      setBookMetadata(null);
      setSelectedBookId(null);
      setSearchResults([]);
      setSearchError(null);
      setShowResults(false);
    } else if (bookMetadata && bookMetadata.title !== value) {
      setBookMetadata(null);
      setSelectedBookId(null);
    }
    setShowResults(Boolean(value?.trim()));
  };

  const handleSelectBook = (book) => {
    skipSearchRef.current = true;
    setSelectedBookId(book.id);
    setBookMetadata(book);
    setBookTitle(book.title || '');
    setSearchResults([]);
    setSearchError(null);
    setShowResults(false);
  };

  const selectedBookSummary = useMemo(() => {
    if (!bookMetadata) return null;
    const authorsLine = bookMetadata.authors?.length ? bookMetadata.authors.join(', ') : null;
    const details = [
      bookMetadata.publisher,
      bookMetadata.publishedDate,
      bookMetadata.pageCount ? `${bookMetadata.pageCount} sayfa` : null,
    ]
      .filter(Boolean)
      .join(' • ');
    return { authorsLine, details };
  }, [bookMetadata]);

  return (
    <Stack spacing={4}>
      {bookMetadata && (
        <Typography variant="body2" color="success.main">
          Seçilen kitap: <strong>{bookMetadata.title}</strong>
          {bookMetadata.authors?.length ? ` • ${bookMetadata.authors.join(', ')}` : ''}
        </Typography>
      )}
      <Box sx={{ position: 'relative', zIndex: 1 }}>
        <Typography variant="h6" gutterBottom>
          Kitap adı
        </Typography>
        <ClickAwayListener onClickAway={() => setShowResults(false)}>
          <Box sx={{ position: 'relative' }}>
            <TextField
              fullWidth
              placeholder="Örn. Yapay Zeka İmparatorluğu"
              value={bookTitle}
              onChange={handleTitleChange}
              onFocus={() => searchResults.length && setShowResults(true)}
              InputProps={{ sx: { borderRadius: 2 } }}
            />
            {showResults && searchResults.length > 0 && bookTitle?.trim() && (
              <Paper
                variant="outlined"
                sx={{
                  position: 'absolute',
                  top: 'calc(100% + 8px)',
                  left: 0,
                  right: 0,
                  borderRadius: 1.2,
                  zIndex: 10,
                  maxHeight: 420,
                  display: 'flex',
                  flexDirection: 'column',
                  overflow: 'hidden',
                  boxShadow: (theme) => theme.shadows[6],
                }}
              >
                <Typography variant="subtitle2" sx={{ px: 2, pt: 2, pb: 1, color: 'text.secondary' }}>
                  Google Books sonuçları
                </Typography>
                <Divider />
                <Box sx={{ flex: 1, overflowY: 'auto', pr: 1.5 }}>
                  <Stack divider={<Divider />} spacing={0}>
                    {searchResults.map((book) => {
                      const detailLine = [
                        book.publisher,
                        book.publishedDate,
                        book.pageCount ? `${book.pageCount} sayfa` : null,
                      ]
                        .filter(Boolean)
                        .join(' • ');
                      const ratingLine = [
                        book.averageRating ? `Puan ${book.averageRating}/5` : null,
                        book.ratingsCount ? `${book.ratingsCount} oy` : null,
                        book.language ? book.language.toUpperCase() : null,
                      ]
                        .filter(Boolean)
                        .join(' • ');
                      const isSelected = selectedBookId === book.id;
                      return (
                        <Box
                        key={book.id}
                        role="button"
                        onClick={() => handleSelectBook(book)}
                        sx={{
                          px: 2,
                          py: 2,
                          display: 'flex',
                          gap: 2,
                          alignItems: 'flex-start',
                          cursor: 'pointer',
                          bgcolor: isSelected ? 'rgba(231,193,121,0.15)' : 'transparent',
                          transition: 'background-color 0.2s ease',
                        }}
                      >
                        <Box
                          sx={{
                            width: 64,
                            height: 96,
                            borderRadius: 0.3,
                            overflow: 'hidden',
                            bgcolor: '#f0ece4',
                            flexShrink: 0,
                            border: '1px solid',
                            borderColor: 'divider',
                          }}
                        >
                          {book.thumbnail ? (
                            <Box
                              component="img"
                              src={book.thumbnail}
                              alt={`${book.title} kapak görseli`}
                              sx={{ width: '100%', height: '100%', objectFit: 'cover' }}
                              loading="lazy"
                            />
                          ) : (
                            <Stack alignItems="center" justifyContent="center" sx={{ height: '100%' }}>
                              <Typography variant="caption" color="text.secondary">
                                Kapak yok
                              </Typography>
                            </Stack>
                          )}
                        </Box>
                        <Box>
                          <Typography variant="subtitle1" sx={{ fontWeight: 600 }}>
                            {book.title}
                          </Typography>
                          {book.subtitle && (
                            <Typography variant="body2" color="text.secondary">
                              {book.subtitle}
                            </Typography>
                          )}
                          <Typography
                            variant="body2"
                            color="text.secondary"
                            sx={{ fontStyle: 'italic', mt: 0.5 }}
                          >
                            {book.authors?.length ? book.authors.join(', ') : 'Yazar bilgisi bulunamadı'}
                          </Typography>
                          {detailLine && (
                            <Typography variant="caption" color="text.secondary" display="block" mt={0.5}>
                              {detailLine}
                            </Typography>
                          )}
                          {ratingLine && (
                            <Typography variant="caption" color="text.secondary" display="block">
                              {ratingLine}
                            </Typography>
                          )}
                          {book.categories?.length > 0 && (
                            <Typography variant="caption" color="text.secondary" display="block" mt={0.5}>
                              {book.categories.join(', ')}
                            </Typography>
                          )}
                        </Box>
                      </Box>
                    );
                  })}
                </Stack>
              </Box>
            </Paper>
            )}
          </Box>
        </ClickAwayListener>
        <Typography variant="body2" color="text.secondary" mt={1}>
          Google Books veritabanında arama yapmak için kitap adını yaz. Seçtiğin kaydın tüm meta bilgileri EPUB&apos;a işlenecek.
        </Typography>
        {searching && <LinearProgress sx={{ mt: 2, borderRadius: 999 }} />}
        {searchError && bookTitle.trim() && !searching && (
          <Typography variant="body2" color="error.main" mt={1}>
            {searchError}
          </Typography>
        )}
      </Box>
      <Box {...getRootProps()} sx={dropzoneStyle}>
        <input {...getInputProps()} />
        <Typography variant="h5" gutterBottom>
          Görselleri sürükleyip bırak veya tıkla
        </Typography>
        <Typography color="text.secondary" gutterBottom>
          .png, .jpg, .jpeg formatlarında çoklu dosya yükleyebilirsin.
        </Typography>
        <Button variant="contained" color="primary">
          Dosya seç
        </Button>
        {isDragActive && (
          <Typography mt={2} fontWeight={600}>
            Bırak ve yükleyelim!
          </Typography>
        )}
      </Box>

      <Box>
        <Typography variant="h6" gutterBottom>
          Yüklenen görseller ({uploadedImages.length})
        </Typography>
        {uploadedImages.length === 0 ? (
          <Typography color="text.secondary">
            Henüz görsel yüklenmedi.
          </Typography>
        ) : (
          <Grid container spacing={2}>
            {uploadedImages.map((image) => (
              <Grid item xs={12} sm={6} md={4} lg={3} key={image.id}>
                <Card>
                  <CardActionArea component="div">
                    <CardMedia
                      component="img"
                      height="160"
                      image={image.previewUrl}
                      alt={image.filename}
                    />
                    <CardContent>
                      <Typography variant="body2" noWrap>
                        {image.filename}
                      </Typography>
                      <Button
                        variant={image.id === coverImageId ? 'contained' : 'outlined'}
                        size="small"
                        fullWidth
                        sx={{ mt: 1 }}
                        onClick={(event) => {
                          event.stopPropagation();
                          handleCoverToggle(image.id);
                        }}
                      >
                        {image.id === coverImageId ? 'Kapak seçildi' : 'Kapak olarak işaretle'}
                      </Button>
                    </CardContent>
                  </CardActionArea>
                </Card>
              </Grid>
            ))}
          </Grid>
        )}
      </Box>

      <Stack direction={{ xs: 'column', sm: 'row' }} spacing={2} justifyContent="flex-end">
        <Button
          variant="contained"
          color="primary"
          disabled={!uploadedImages.length}
          onClick={() => navigate('/crop')}
        >
          Devam et
        </Button>
      </Stack>
    </Stack>
  );
};

export default UploadStep;
