import React, { useEffect, useState, useCallback } from 'react';
import {
  View,
  Text,
  Alert,
  StyleSheet,
  FlatList,
  Platform,
  TouchableOpacity,
  Button
} from 'react-native';
import { SafeAreaView } from 'react-native-safe-area-context';
import { useCart } from '@/context/cartContext';
import { getAuth } from 'firebase/auth';
import { collection, addDoc } from 'firebase/firestore';
import { query, orderBy, limit, getDocs } from 'firebase/firestore';

import { db } from '@/firebase/config';
import CartItem from '@/components/CartItem';
import { ArrowLeft } from 'lucide-react-native';
import Animated, {
  useAnimatedStyle,
  useSharedValue,
  withSequence,
  withTiming,
} from 'react-native-reanimated';
import * as Haptics from 'expo-haptics';
import { useRouter } from 'expo-router';
import COLORS from '@/constants/colors';
import { CartItem as CartItemType } from '@/context/cartContext';

export default function CartScreen() {
  const { cart, clearCart, updateQuantity } = useCart();
  const totalAmount = cart.total;
  const [isProcessingOrder, setIsProcessingOrder] = useState(false);
  const auth = getAuth();
  const router = useRouter();

  const totalValue = useSharedValue(1);
  const buttonScale = useSharedValue(1);

  

  const totalAnimatedStyle = useAnimatedStyle(() => ({
    transform: [{ scale: totalValue.value }],
  }));

  const handleConfirmOrder = useCallback(async () => {
    if (totalAmount <= 0) {
      Alert.alert('Panier vide', 'Veuillez ajouter des produits à votre panier');
      return;
    }
  
    setIsProcessingOrder(true);
    buttonScale.value = withSequence(
      withTiming(0.95, { duration: 100 }),
      withTiming(1, { duration: 150 })
    );
  
    if (Platform.OS !== 'web') {
      Haptics.notificationAsync(Haptics.NotificationFeedbackType.Success);
    }
  
    try {
      const user = auth.currentUser;
      if (!user) {
        Alert.alert('Utilisateur non connecté', 'Veuillez vous connecter pour passer une commande.');
        return;
      }
  
      // Utilisation de query pour appliquer orderBy et limit
      const orderRef = collection(db, 'orders');
      const q = query(orderRef, orderBy('createdAt', 'desc'), limit(1));
      const orderSnapshot = await getDocs(q);
      let lastOrderId = 0;
  
      if (!orderSnapshot.empty) {
        const lastOrderDoc = orderSnapshot.docs[0].data();
        lastOrderId = parseInt(lastOrderDoc.orderId.replace(/^0+/, '')) || 0;  // Remove leading zeros
      }
  
      const newOrderId = String(lastOrderId + 1).padStart(3, '0'); // Generate the new order ID
  
      const orderData: any = {
        orderId: newOrderId,  // Use the generated ID
        userId: user.uid,
        status: 'En attente',
        createdAt: new Date().toISOString(),
        totalAmount: totalAmount,
      };
  
      // Add each item in the cart to the orderData
      cart.items.forEach((item, index) => {
        orderData[`item${index + 1}`] = {
          name: item.name,
          quantity: item.quantity,
        };
      });
  
      // Add the order to Firestore
      await addDoc(collection(db, 'orders'), orderData);
      Alert.alert('Commande confirmée', `Montant Total : ${totalAmount}DT`);
  
      clearCart();
    } catch (error) {
      console.error('Erreur commande :', error);
      Alert.alert('Erreur', "Impossible d'enregistrer la commande.");
    } finally {
      setIsProcessingOrder(false);
    }
  }, [cart, totalAmount, auth]);
  

  const renderItem = useCallback(({ item }: { item: CartItemType }) => (
    <CartItem
      item={item}
      onUpdateQuantity={(id, newQty) => {
        updateQuantity(id, newQty);
        totalValue.value = withSequence(
          withTiming(1.05, { duration: 100 }),
          withTiming(1, { duration: 100 })
        );
      }}
    />
  ), []);

  const keyExtractor = useCallback((item: CartItemType) => item.id, []);

  return (
    <SafeAreaView style={styles.container}>
      <View style={styles.header}>
        <TouchableOpacity style={styles.backButton} onPress={() => router.back()}>
          <ArrowLeft size={24} color="#666" />
        </TouchableOpacity>
        <Text style={styles.headerTitle}>Mon Panier</Text>
      </View>

      <View style={styles.content}>
        <FlatList
          data={cart.items}
          renderItem={renderItem}
          keyExtractor={keyExtractor}
          showsVerticalScrollIndicator={false}
          ListEmptyComponent={
            <View style={styles.emptyContainer}>
              <Text style={styles.emptyText}>Votre panier est vide</Text>
            </View>
          }
        />
      </View>

      <View style={styles.footer}>
        <View style={styles.totalContainer}>
          <Text style={styles.totalLabel}>Total : </Text>
          <Animated.Text style={[styles.totalAmount, totalAnimatedStyle]}>
            {totalAmount}DT
          </Animated.Text>
        </View>

        <TouchableOpacity style={styles.ConfirmButton} 
          onPress={() => {
            Alert.alert(
              'Confirmer la commande',
              'Êtes-vous sûr de vouloir confirmer la commande?',
              [
                {text : 'Annuler', style: 'cancel'},
                {text: 'Confirmer', style: 'destructive', onPress: handleConfirmOrder }
              ]
            );
          }

          } 
          disabled={totalAmount <= 0}>
            <Text style={styles.ConfirmButtonText}>Ajouter au panier</Text>
        </TouchableOpacity>

        <TouchableOpacity style={styles.clearCartButton} 
          onPress={() => {
            Alert.alert(
              'Vider le panier',
              'Êtes-vous sûr de vouloir supprimer tous les articles du panier ?',
              [
                { text: 'Annuler', style: 'cancel' },
                { text: 'Confirmer', style: 'destructive', onPress: clearCart },
              ]
            );
          }}
          disabled={cart.items.length === 0}>
          <Text style={styles.clearCartButtonText}>Vider le panier</Text>
        </TouchableOpacity>
      </View>
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  container: { flex: 1, 
    backgroundColor: '#fff' },
  header: {
    height: 60,
    justifyContent: 'center',
    alignItems: 'center',
    position: 'relative',
    backgroundColor: '#fff',
    borderBottomWidth: 1,
    borderBottomColor: '#eee',
    marginTop: 5,
  },
  backButton: {
    position: 'absolute',
    left: 20,
    top: '50%',
    transform: [{ translateY: -12 }],
  },
  headerTitle: {
    fontSize: 20,
    fontWeight: '600',
    color: '#333',
  },
  content: {
    flex: 1,
    padding: 5,
  },
  footer: {
    paddingHorizontal: 20,
    paddingVertical: 10,
    backgroundColor: COLORS.background_user,
    borderTopWidth: 1,
    borderTopColor: COLORS.secondary,
  },
  totalContainer: {
    flexDirection: 'row',
    justifyContent: 'center',
    alignItems: 'center',
    marginBottom: 10,
  },
  totalLabel: {
    fontSize: 20,
  },
  totalAmount: {
    fontSize: 20,
    color: COLORS.primary
    },
  ConfirmButton: {
    backgroundColor: '#B07B4F',
    borderRadius: 12,
    padding: 16,
    alignItems: 'center',
  },
  ConfirmButtonText: {
    color: '#fff',
    fontSize: 16,
    fontWeight: '600',
  },
  clearCartButton: {
    backgroundColor: '#D9534F',
    borderRadius: 12,
    padding: 16,
    alignItems: 'center',
    marginTop: 10,  // Adding some space above the button
  },
  clearCartButtonText: {
    color: '#fff',
    fontSize: 16,
    fontWeight: '600',
  },
  
  emptyContainer: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    paddingVertical: 10,
  },
  emptyText: {
    fontSize: 18,
  },
});