import { Feather } from '@expo/vector-icons';
import * as ImagePicker from 'expo-image-picker';
import { useCallback, useEffect, useState } from 'react';
import {
  Alert,
  FlatList,
  Image,
  Modal,
  Pressable,
  StyleSheet,
  Text,
  View,
} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { classifyImageUri, type ClassificationResult } from '../lib/classifier';
import { loadGallery, removeFromGallery, type GalleryItem } from '../lib/gallery';
import { colors, layout } from '../theme';
import { GlassSurface } from './GlassSurface';
import { HotDogIcon } from './HotDogIcon';

type ScanGalleryProps = {
  visible: boolean;
  onClose: () => void;
  onSelect: (item: GalleryItem) => void;
  onImport: (uri: string, result: ClassificationResult) => void;
};

export function ScanGallery({
  visible,
  onClose,
  onSelect,
  onImport,
}: ScanGalleryProps) {
  const [items, setItems] = useState<GalleryItem[]>([]);
  const [loading, setLoading] = useState(false);

  const refresh = useCallback(async () => {
    setItems(await loadGallery());
  }, []);

  useEffect(() => {
    if (visible) void refresh();
  }, [visible, refresh]);

  const handleImport = useCallback(async () => {
    const permission = await ImagePicker.requestMediaLibraryPermissionsAsync();
    if (!permission.granted) {
      Alert.alert('Photos access needed to import an image.');
      return;
    }

    setLoading(true);
    try {
      const picked = await ImagePicker.launchImageLibraryAsync({
        mediaTypes: ['images'],
        quality: 0.9,
      });

      if (picked.canceled || !picked.assets[0]?.uri) return;

      const uri = picked.assets[0].uri;
      const result = await classifyImageUri(uri);
      onImport(uri, result);
      onClose();
    } catch {
      Alert.alert('Could not scan that photo.');
    } finally {
      setLoading(false);
    }
  }, [onClose, onImport]);

  const handleDelete = useCallback(
    (item: GalleryItem) => {
      Alert.alert('Delete scan?', undefined, [
        { text: 'Cancel', style: 'cancel' },
        {
          text: 'Delete',
          style: 'destructive',
          onPress: () => {
            void removeFromGallery(item.id).then(refresh);
          },
        },
      ]);
    },
    [refresh],
  );

  return (
    <Modal visible={visible} animationType="slide" onRequestClose={onClose}>
      <View style={styles.root}>
        <SafeAreaView edges={['top', 'left', 'right']} style={styles.safe}>
          <View style={styles.headerWrap}>
            <GlassSurface appearance="sheet" style={styles.header}>
              <View style={styles.headerRow}>
                <Pressable
                  onPress={onClose}
                  style={styles.headerButton}
                  accessibilityLabel="Close gallery"
                >
                  <Feather name="x" size={22} color={colors.text} />
                </Pressable>
                <Text style={styles.headerTitle}>Gallery</Text>
                <Pressable
                  onPress={() => void handleImport()}
                  style={styles.headerButton}
                  disabled={loading}
                  accessibilityLabel="Import photo"
                >
                  <Feather name="plus" size={22} color={colors.text} />
                </Pressable>
              </View>
            </GlassSurface>
          </View>

          <FlatList
            data={items}
            keyExtractor={(item) => item.id}
            numColumns={3}
            contentContainerStyle={styles.grid}
            columnWrapperStyle={styles.gridRow}
            ListEmptyComponent={
              <View style={styles.empty}>
                <HotDogIcon size={40} color={colors.textMuted} />
                <Text style={styles.emptyTitle}>No scans yet</Text>
                <Text style={styles.emptyBody}>
                  Scan a hot dog or tap + to import a photo.
                </Text>
              </View>
            }
            renderItem={({ item }) => (
              <Pressable
                style={styles.cell}
                onPress={() => {
                  onSelect(item);
                  onClose();
                }}
                onLongPress={() => handleDelete(item)}
                accessibilityLabel={
                  item.result.isHotDog ? 'Hot dog scan' : 'Not hot dog scan'
                }
              >
                <Image source={{ uri: item.uri }} style={styles.thumb} />
                <View
                  style={[
                    styles.badge,
                    {
                      backgroundColor: item.result.isHotDog
                        ? colors.hotDog
                        : colors.notHotDog,
                    },
                  ]}
                >
                  {item.result.isHotDog ? (
                    <HotDogIcon size={12} color={colors.text} />
                  ) : (
                    <Feather name="x" size={12} color={colors.text} />
                  )}
                </View>
              </Pressable>
            )}
          />
        </SafeAreaView>
      </View>
    </Modal>
  );
}

const GAP = 8;

const styles = StyleSheet.create({
  root: {
    flex: 1,
    backgroundColor: colors.bg,
  },
  safe: {
    flex: 1,
    paddingHorizontal: 16,
  },
  headerWrap: {
    marginTop: layout.galleryHeaderTop,
    marginBottom: 16,
  },
  header: {
    paddingHorizontal: 8,
    paddingVertical: 8,
  },
  headerRow: {
    flexDirection: 'row',
    alignItems: 'center',
    justifyContent: 'space-between',
  },
  headerButton: {
    width: layout.controlSize,
    height: layout.controlSize,
    alignItems: 'center',
    justifyContent: 'center',
  },
  headerTitle: {
    color: colors.text,
    fontSize: 17,
    fontWeight: '700',
  },
  grid: {
    paddingBottom: 24,
    flexGrow: 1,
  },
  gridRow: {
    gap: GAP,
    marginBottom: GAP,
  },
  cell: {
    flex: 1,
    aspectRatio: 1,
    borderRadius: layout.radius,
    overflow: 'hidden',
    backgroundColor: 'rgba(255, 255, 255, 0.04)',
  },
  thumb: {
    width: '100%',
    height: '100%',
  },
  badge: {
    position: 'absolute',
    top: 6,
    right: 6,
    width: 22,
    height: 22,
    borderRadius: 11,
    alignItems: 'center',
    justifyContent: 'center',
  },
  empty: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
    paddingTop: 80,
    gap: 10,
    paddingHorizontal: 32,
  },
  emptyTitle: {
    color: colors.text,
    fontSize: 18,
    fontWeight: '700',
  },
  emptyBody: {
    color: colors.textMuted,
    fontSize: 15,
    textAlign: 'center',
    lineHeight: 21,
  },
});