import React, { useState, useCallback } from 'react';
import { View, ScrollView, Alert } from 'react-native';
import { AppContainer, MyText, tw, useMarkDataFetchers, MyTouchableOpacity, MyTextInput } from 'common-ui';
import { useLocalSearchParams, useRouter } from 'expo-router';
import { useFocusEffect } from '@react-navigation/native';
import { useAppStore } from '@/src/store/appStore';
import { trpc } from '@/src/trpc-client';
import MaterialIcons from '@expo/vector-icons/MaterialIcons';
import dayjs from 'dayjs';

interface CouponCardProps {
  coupon: {
    id: number;
    code: string;
    discountType: 'percentage' | 'flat';
    discountValue: number;
    maxValue?: number;
    minOrder?: number;
    description: string;
    validTill?: string | Date;
    usageCount: number;
    maxLimitForUser?: number;
    isExpired: boolean;
    isUsedUp: boolean;
  };
}

function CouponCard({ coupon }: CouponCardProps) {
  const getStatusColor = () => {
    if (coupon.isExpired) return 'text-red-500';
    if (coupon.isUsedUp) return 'text-orange-500';
    return 'text-green-600';
  };

  const getStatusText = () => {
    if (coupon.isExpired) return 'Expired';
    if (coupon.isUsedUp) return 'Used';
    return 'Available';
  };

  const formatDate = (date?: string | Date) => {
    if (!date) return 'No expiry';
    return dayjs(date).format('DD MMM YYYY');
  };

  return (
    <View style={tw`bg-white rounded-lg p-4 mb-3 shadow-sm border border-gray-100`}>
      <View style={tw`flex-row justify-between items-start mb-2`}>
        <View style={tw`flex-1`}>
          <MyText weight="semibold" style={tw`text-lg text-gray-800 mb-1`}>
            {coupon.code}
          </MyText>
          <MyText style={tw`text-sm text-gray-600 mb-2`}>
            {coupon.description}
          </MyText>
        </View>
        <View style={tw`items-end`}>
          <MyText style={tw`${getStatusColor()} text-sm font-medium mb-1`}>
            {getStatusText()}
          </MyText>
          {coupon.maxLimitForUser && (
            <MyText style={tw`text-xs text-gray-500`}>
              Used: {coupon.usageCount}/{coupon.maxLimitForUser}
            </MyText>
          )}
        </View>
      </View>

      <View style={tw`flex-row justify-between items-center`}>
        <MyText style={tw`text-xs text-gray-500`}>
          Valid till: {formatDate(coupon.validTill)}
        </MyText>
        <MyTouchableOpacity
          style={tw`bg-blue-500 px-3 py-1 rounded-full`}
          disabled={coupon.isExpired || coupon.isUsedUp}
        >
          <MyText style={tw`text-white text-xs font-medium`}>
            {coupon.isExpired || coupon.isUsedUp ? 'Unavailable' : 'Apply'}
          </MyText>
        </MyTouchableOpacity>
      </View>
    </View>
  );
}

function CouponSection({
  title,
  coupons,
  emptyMessage
}: {
  title: string;
  coupons: CouponCardProps['coupon'][];
  emptyMessage: string;
}) {
  return (
    <View style={tw`mb-6`}>
      <MyText weight="semibold" style={tw`text-lg text-gray-800 mb-3`}>
        {title}
      </MyText>

      {coupons.length === 0 ? (
        <View style={tw`bg-gray-50 rounded-lg p-6 items-center`}>
          <MaterialIcons name="local-offer" size={48} color="#9CA3AF" />
          <MyText style={tw`text-gray-500 text-center mt-2`}>
            {emptyMessage}
          </MyText>
        </View>
      ) : (
        coupons.map(coupon => (
          <CouponCard key={coupon.id} coupon={coupon} />
        ))
      )}
    </View>
  );
}

export default function Coupons() {
  const router = useRouter();
  const { from } = useLocalSearchParams<{ from?: string }>();
  const setHideTabsNavKey = useAppStore((state) => state.setHideTabsNavKey);

  // Hide bottom tab bar when opened from the cart page
  useFocusEffect(
    useCallback(() => {
      if (from !== 'cart') return;
      setHideTabsNavKey('coupons-from-cart', true);
      return () => setHideTabsNavKey('coupons-from-cart', false);
    }, [from, setHideTabsNavKey])
  );

  const { data, isLoading, error, refetch } = trpc.user.coupon.getMyCoupons.useQuery();
  const [couponCode, setCouponCode] = useState('');

  const redeemCouponMutation = trpc.user.coupon.redeemReservedCoupon.useMutation({
    onSuccess: () => {
      setCouponCode('');
      refetch();
      Alert.alert('Success', 'Coupon added successfully!');
    },
    onError: (error: any) => {
      Alert.alert('Error', error.message || 'Failed to add coupon. Please check the code and try again.');
    }
  });

  useMarkDataFetchers(() => {
    refetch();
  });

  if (isLoading) {
    return (
      <AppContainer>
        <View style={tw`flex-1 justify-center items-center`}>
          <MyText style={tw`text-gray-600`}>Loading coupons...</MyText>
        </View>
      </AppContainer>
    );
  }

  if (error) {
    return (
      <AppContainer>
        <View style={tw`flex-1 justify-center items-center p-4`}>
          <MaterialIcons name="error-outline" size={48} color="#EF4444" />
          <MyText style={tw`text-red-600 text-center mt-2`}>
            Failed to load coupons. Please try again.
          </MyText>
        </View>
      </AppContainer>
    );
  }

  const personalCoupons = data?.data?.personal || [];
  const generalCoupons = data?.data?.general || [];

  return (
    <AppContainer>
      <View style={tw`flex-1 p-4`}>
        {from === 'cart' && (
          <MyTouchableOpacity
            onPress={() => router.navigate('/(drawer)/(tabs)/home/cart')}
            style={tw`p-2 -ml-2 mr-1 mb-2 self-start`}
            activeOpacity={0.7}
          >
            <MaterialIcons name="chevron-left" size={28} color="#374151" />
          </MyTouchableOpacity>
        )}
        <View style={tw`bg-white rounded-lg p-4 mb-6 shadow-sm border border-gray-100`}>
          <MyText style={tw`text-lg font-semibold text-gray-800 mb-3`}>
            Add a Coupon
          </MyText>
          <MyTextInput
            placeholder="Enter coupon code"
            value={couponCode}
            onChangeText={setCouponCode}
            style={tw`mb-4`}
          />
          <MyTouchableOpacity
            style={tw`bg-blue-500 px-4 py-3 rounded-lg items-center ${
              redeemCouponMutation.isPending || couponCode.trim().length < 4 ? 'opacity-50' : ''
            }`}
            disabled={redeemCouponMutation.isPending || couponCode.trim().length < 4}
            onPress={() => {
              if (couponCode.trim().length >= 4) {
                redeemCouponMutation.mutate({ secretCode: couponCode.trim().toUpperCase() });
              }
            }}
          >
            <MyText style={tw`text-white font-semibold`}>
              {redeemCouponMutation.isPending ? 'Adding...' : 'Add Coupon'}
            </MyText>
          </MyTouchableOpacity>
        </View>

        <CouponSection
          title="Only for Me"
          coupons={personalCoupons}
          emptyMessage="No personal coupons available"
        />

        <CouponSection
          title="Apply to All"
          coupons={generalCoupons}
          emptyMessage="No general coupons available"
        />
      </View>
    </AppContainer>
  );
}