import React, { useState, useEffect, useCallback, useRef } from 'react';
import {
  View,
  Text,
  ScrollView,
  TouchableOpacity,
  FlatList,
  Image,
  NativeSyntheticEvent,
  NativeScrollEvent,
  Dimensions,
} from 'react-native';
import {
  useNavigation,
  CompositeNavigationProp,
  useFocusEffect,
} from '@react-navigation/native';
import { BottomTabNavigationProp } from '@react-navigation/bottom-tabs';
import { StackNavigationProp } from '@react-navigation/stack';
import { getStyles } from './homeScreen.styles';
import { ProductCard, SearchBar } from '@components';
import { useAppTheme } from '@theme';
import { Product } from '../../../interfaces';
import { AppStackParamList } from '../../../navigation/appStack';
import { MainTabParamList } from '../../../navigation/mainTabNavigator';
import {
  fetchCustomerDetails,
  getAllOffersThunk,
  useAppDispatch,
  useAppSelector,
} from '@store';
import { getAllCategoriesThunk, getAllProductsThunk } from './thunk';

type NavProp = CompositeNavigationProp<
  BottomTabNavigationProp<MainTabParamList, 'HomeScreen'>,
  StackNavigationProp<AppStackParamList>
>;

const { width } = Dimensions.get('window');
const BANNER_STEP = width - 32 + 12; // card width + margin

const ALL_CATEGORY = { id: 'all', name: 'All', slug: 'all', imageUrl: null, isActive: true, parentId: null };

const getCategoryEmoji = (name: string): string => {
  const n = name.toLowerCase();
  if (n.includes('food')) return '🍔';
  if (n.includes('grocer')) return '🛒';
  if (n.includes('pharma') || n.includes('medic')) return '💊';
  if (n.includes('meat')) return '🥩';
  if (n.includes('flower')) return '💐';
  if (n.includes('electronic')) return '📱';
  if (n.includes('cloth') || n.includes('fashion')) return '👗';
  if (n.includes('bakery') || n.includes('cake')) return '🎂';
  return '📦';
};

const PROMOS = [
  {
    key: 'promo1',
    colors: ['#05824C', '#0AA25E'],
    eyebrow: 'Limited time',
    title: '50% OFF',
    subtitle: 'On your first order, up to ₹150',
    cta: 'Order now',
  },
  {
    key: 'promo2',
    colors: ['#7B3FF2', '#9B6BF5'],
    eyebrow: 'Free delivery',
    title: '₹0 Delivery',
    subtitle: 'On orders above ₹299 today',
    cta: 'Explore',
  },
  {
    key: 'promo3',
    colors: ['#E85D3D', '#F0805F'],
    eyebrow: 'Pharmacy',
    title: 'Meds in 20 min',
    subtitle: 'Genuine medicines, fast delivery',
    cta: 'Shop now',
  },
];

export const HomeScreen: React.FC = () => {
  const { colors } = useAppTheme();
  const styles = getStyles(colors);
  const navigation = useNavigation<NavProp>();

  const dispatch = useAppDispatch();
  const { products, isLoading, categories } = useAppSelector(
    state => state.home,
  );

  const [selectedCategory, setSelectedCategory] = useState('all');
  const [activeBanner, setActiveBanner] = useState(0);

  useEffect(() => {
    dispatch(getAllProductsThunk());
    dispatch(fetchCustomerDetails());
    dispatch(getAllCategoriesThunk());
  }, [dispatch]);
  useFocusEffect(
    useCallback(() => {
      dispatch(getAllOffersThunk());
    }, [dispatch]),
  );

  // Build category list: prepend synthetic 'All', then append API categories
  const dynamicCategories = [ALL_CATEGORY, ...categories];

  const filteredProducts =
    selectedCategory === 'all'
      ? products
      : products.filter(p => p.category?.name === selectedCategory);

  const handleSearchFocus = useCallback(() => {
    navigation.navigate('SearchScreen');
  }, [navigation]);

  const handleBannerScroll = useCallback(
    (e: NativeSyntheticEvent<NativeScrollEvent>) => {
      const index = Math.round(e.nativeEvent.contentOffset.x / BANNER_STEP);
      setActiveBanner(index);
    },
    [],
  );

  return (
    <ScrollView style={styles.container} showsVerticalScrollIndicator={false}>
      {/* Top bar */}
      <View style={styles.topBar}>
        <TouchableOpacity style={styles.addressBar} activeOpacity={0.7}>
          <View style={styles.pinBadge}>
            <Text style={styles.pinEmoji}>📍</Text>
          </View>
          <View style={styles.addressTextWrap}>
            <Text style={styles.addressLabel}>Deliver to</Text>
            <View style={styles.addressRow}>
              <Text style={styles.addressText} numberOfLines={1}>
                Koramangala 4th Block
              </Text>
              <Text style={styles.dropdownArrow}>▼</Text>
            </View>
          </View>
        </TouchableOpacity>

        <TouchableOpacity
          style={styles.avatarButton}
          activeOpacity={0.7}
          onPress={() => navigation.navigate('CartScreen')}
        >
          <Text style={styles.avatarEmoji}>🧺</Text>
          <View style={styles.notifDot} />
        </TouchableOpacity>
      </View>

      {/* Search */}
      <View style={styles.searchWrap}>
        <SearchBar
          value=""
          onChangeText={() => {}}
          placeholder="Search providers or items..."
          onFocus={handleSearchFocus}
        />
      </View>

      {/* Promo carousel */}
      <FlatList
        data={PROMOS}
        horizontal
        keyExtractor={item => item.key}
        showsHorizontalScrollIndicator={false}
        contentContainerStyle={styles.bannerListContent}
        snapToInterval={BANNER_STEP}
        decelerationRate="fast"
        onScroll={handleBannerScroll}
        scrollEventThrottle={16}
        renderItem={({ item }) => (
          <View
            style={[styles.bannerCard, { backgroundColor: item.colors[0] }]}
          >
            <View style={styles.bannerDecoCircleLg} />
            <View style={styles.bannerDecoCircleSm} />
            <View>
              <Text style={styles.bannerEyebrow}>{item.eyebrow}</Text>
              <Text style={styles.bannerText}>{item.title}</Text>
              <Text style={styles.bannerSubtext}>{item.subtitle}</Text>
            </View>
            <View style={styles.bannerCta}>
              <Text style={styles.bannerCtaText}>{item.cta}</Text>
            </View>
          </View>
        )}
      />
      <View style={styles.dotsRow}>
        {PROMOS.map((_, i) => (
          <View
            key={i}
            style={[styles.dot, i === activeBanner && styles.dotActive]}
          />
        ))}
      </View>

      {/* Categories */}
      <View style={styles.categorySection}>
        <FlatList
          horizontal
          data={dynamicCategories}
          keyExtractor={item => item.id}
          showsHorizontalScrollIndicator={false}
          contentContainerStyle={styles.chipRow}
          renderItem={({ item }) => {
            const isSelected = selectedCategory === item.id;
            const emoji =
              item.id === 'all' ? '🏠' : getCategoryEmoji(item.name);
            return (
              <TouchableOpacity
                style={styles.categoryItem}
                activeOpacity={0.75}
                onPress={() => {
                  if (item.id === 'all') {
                    setSelectedCategory('all');
                  } else {
                    navigation.navigate('SearchScreen', {
                      categoryId: item.id,
                      categoryName: item.name,
                    });
                  }
                }}
              >
                <View
                  style={[
                    styles.categoryCircle,
                    isSelected && styles.categoryCircleSelected,
                  ]}
                >
                  <Text style={styles.categoryIcon}>{emoji}</Text>
                </View>
                <Text
                  style={[
                    styles.categoryLabel,
                    isSelected && styles.categoryLabelSelected,
                  ]}
                  numberOfLines={1}
                >
                  {item.name}
                </Text>
              </TouchableOpacity>
            );
          }}
        />
      </View>

      {/* Section header */}
      <View style={styles.sectionHeaderRow}>
        <View>
          <Text style={styles.sectionTitle}>
            {selectedCategory === 'all' ? 'Popular near you' : selectedCategory}
          </Text>
          <Text style={styles.sectionSubtitle}>
            {filteredProducts.length} product
            {filteredProducts.length === 1 ? '' : 's'} available
          </Text>
        </View>
        <TouchableOpacity activeOpacity={0.7}>
          <Text style={styles.seeAllText}>See all</Text>
        </TouchableOpacity>
      </View>

      {/* Product list */}
      <View style={styles.providerList}>
        {filteredProducts.length === 0 && (
          <View style={[styles.emptyWrap, { width: '100%' }]}>
            <Text style={styles.emptyEmoji}>🛍️</Text>
            <Text style={styles.emptyText}>No products found</Text>
          </View>
        )}

        {filteredProducts.map(product => (
          <ProductCard
            key={product.id}
            id={product.id}
            imageUrl={product.imageUrl}
            name={product.name}
            price={product.price}
            compareAtPrice={product.compareAtPrice}
            brand={product.brand || product.merchant?.name}
            currency={product.currency === 'INR' ? '₹' : product.currency}
            onPress={() => {
              navigation.navigate('ProviderDetailsScreen', {
                providerId: product.id,
                providerName: product.name,
              });
            }}
          />
        ))}
      </View>

      <View style={{ height: 24 }} />
    </ScrollView>
  );
};