import React, { useState, useEffect } from 'react';
import { View, TouchableOpacity, Alert } from 'react-native';
import { AppContainer, MyText, tw } from 'common-ui';
import MaterialIcons from '@expo/vector-icons/MaterialIcons';
import { useRouter, useLocalSearchParams } from 'expo-router';
import { FormikHelpers } from 'formik';
import BannerForm, { BannerFormData } from '@/components/BannerForm';
import { trpc } from '@/src/trpc-client';
import type { Banner as SharedBanner } from '@packages/shared';

// Form/hardened view of the shared banner (string dates, non-null editable fields)
type Banner = Omit<
  SharedBanner,
  'description' | 'skuIds' | 'redirectUrl' | 'serialNum' | 'createdAt' | 'lastUpdated'
> & {
  description?: string;
  skuIds?: number[];
  redirectUrl?: string;
  serialNum: number;
  createdAt: string;
  lastUpdated: string;
};

export default function EditBanner() {
  const router = useRouter();
  const { id } = useLocalSearchParams();
  const bannerId = id as string;
  
  const [isLoading, setIsLoading] = useState(true);
  const [isSubmitting, setIsSubmitting] = useState(false);
  // Load real banner data from API
  const {data: bannerData } = trpc.admin.banner.getBanner.useQuery({
    id: parseInt(bannerId)
  });
  const { refetch: refetchBanners } = trpc.admin.banner.getBanners.useQuery(undefined, {
    enabled: false,
  });
  const [banner, setBanner] = useState<typeof bannerData>(undefined);
  

  useEffect(() => {
    const loadBanner = async () => {
      try {
        setIsLoading(true);



        if (bannerData) {
          // Handle data format compatibility (productId -> skuIds migration)
          const processedBanner = {
            ...bannerData,
            skuIds: Array.isArray(bannerData.skuIds)
              ? bannerData.skuIds
              : (bannerData.skuIds ? [bannerData.skuIds] : [])
          };

          setBanner(processedBanner);
        } else {
          Alert.alert('Error', 'Banner not found');
          router.back();
        }
      } catch (error) {
        console.error('Failed to load banner:', error);
        Alert.alert('Error', 'Failed to load banner data');
        router.back();
      } finally {
        setIsLoading(false);
      }
    };

    loadBanner();
  }, [bannerId, bannerData]);

  const initialValues: BannerFormData = banner ? {
    name: banner.name,
    imageUrl: banner.imageUrl,
    description: banner.description || '',
    skuIds: banner.skuIds || [],
    redirectUrl: banner.redirectUrl || '',
    // serialNum removed - handled automatically by backend
  } : {
    name: '',
    imageUrl: '',
    description: '',
    skuIds: [],
    redirectUrl: '',
    // serialNum removed - handled automatically by backend
  };

  const updateBannerMutation = trpc.admin.banner.updateBanner.useMutation();

  const handleSubmit = async (values: BannerFormData, imageUrl?: string) => {
    if (!banner) return;

    setIsSubmitting(true);

    try {
      await updateBannerMutation.mutateAsync({
        id: banner.id,
        name: values.name,
        imageUrl: imageUrl || banner.imageUrl,
        description: values.description || undefined,
        skuIds: values.skuIds.length > 0 ? values.skuIds : [],
        redirectUrl: values.redirectUrl || undefined,
      });

      await refetchBanners()
      Alert.alert('Success', 'Banner updated successfully', [
        {
          text: 'OK',
          onPress: () => router.back(),
        }
      ]);
    } catch (error) {
      Alert.alert('Error', 'Failed to update banner. Please try again.');
    } finally {
      setIsSubmitting(false);
    }
  };

  const handleCancel = () => {
    router.back();
  };

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

  if (!banner) {
    return (
      <AppContainer>
        <View style={tw`flex-1 justify-center items-center bg-white`}>
          <MyText style={tw`text-red-600`}>Banner not found</MyText>
        </View>
      </AppContainer>
    );
  }

  return (
    <AppContainer>
      <View style={tw`flex-1 bg-white`}>
        {/* Header */}
        <View style={tw`flex-row items-center justify-between px-6 py-4 border-b border-gray-200`}>
          <TouchableOpacity onPress={handleCancel} style={tw`p-2`}>
            <MaterialIcons name="arrow-back" size={24} color="#374151" />
          </TouchableOpacity>
          <MyText style={tw`text-xl font-bold text-gray-900`}>Edit Banner</MyText>
          <View style={tw`w-10`} />
        </View>

        <BannerForm
          initialValues={initialValues}
          onSubmit={handleSubmit}
          onCancel={handleCancel}
          submitButtonText="Update Banner"
          isSubmitting={isSubmitting}
          existingImageUrl={banner.imageUrl}
        />
      </View>
    </AppContainer>
  );
}