import { router } from 'expo-router';
import { useEffect, useMemo, useState } from 'react';
import { ScrollView, StyleSheet, View } from 'react-native';

import {
  CategoryTabs,
  CommunityGrid,
  FeatureCarousel,
  Header,
  PageLayout,
  SectionHeader,
  StatusBarSpacer,
  type CommunityItem,
  type FeatureItem
} from '@/components/bestai';
import type { FeatureItem as FeatureItemType } from '@/components/bestai/feature-carousel';
import { useAuth } from '@/hooks/use-auth';
import { useAuthGuard } from '@/hooks/use-auth-guard';
import { getActivities, type Activity } from '@/lib/api/activities';
import { categoriesWithChildren } from '@/lib/api/categories-with-children';
import type { CategoryTemplate, CategoryWithChildren } from '@/lib/types/template';

function coalesceText(...values: Array<string | null | undefined>): string {
  for (const value of values) {
    const trimmed = (value ?? '').trim();
    if (trimmed.length > 0) {
      return trimmed;
    }
  }
  return '';
}

function translateTemplateToCommunity(template: CategoryTemplate): CommunityItem | null {
  const image = coalesceText(template.coverImageUrl, template.previewUrl);
  const title = coalesceText(template.titleEn, template.title);
  if (!image || !title) {
    return null;
  }

  const primaryTag = template.tags?.[0];
  const chip = coalesceText(primaryTag?.nameEn, primaryTag?.name, template.aspectRatio) || 'Featured';

  return {
    id: template.id,
    title,
    image,
    chip,
    actionLabel: 'Generate',
  };
}

function translateActivity(activity: Activity): FeatureItem | null {
  const image = (activity.coverUrl || '').trim();
  const title = (activity.titleEn || '').trim() || (activity.title || '').trim();
  if (!image || !title) {
    return null;
  }

  const subtitle = (activity.descEn || '').trim() || (activity.desc || '').trim();

  return {
    id: activity.id,
    title,
    subtitle,
    image,
  };
}

export default function ExploreScreen() {
  const { isAuthenticated } = useAuth();
  const { requireAuth } = useAuthGuard();
  const [activeCategory, setActiveCategory] = useState<string>();
  const [activityFeatures, setActivityFeatures] = useState<FeatureItem[]>([]);
  const [categoryCollection, setCategoryCollection] = useState<CategoryWithChildren[]>([]);

  useEffect(() => {
    const hydrateFeatureCarousel = async () => {
      try {
        const activities = await getActivities({ isActive: true });
        console.log({ activities })

        const curatedFeatures = activities
          .map(translateActivity)
          .filter((feature): feature is FeatureItem => feature !== null);
        if (curatedFeatures.length > 0) {
          setActivityFeatures(curatedFeatures);
        }
      } catch (error) {
        const detail = error instanceof Error ? error.message : String(error);
        console.warn('FeatureCarousel activities feed unavailable:', detail);
      }
    };

    hydrateFeatureCarousel();

    return () => {
    };
  }, []);

  useEffect(() => {
    let isActive = true;

    const hydrateCategories = async () => {
      try {
        const response = await categoriesWithChildren();
        if (!isActive) {
          return;
        }

        const payload = response.success && Array.isArray(response.data) ? response.data : [];
        const curated = payload.filter((category) => category.id && (category.isActive ?? true));

        setCategoryCollection(curated.length > 0 ? curated : payload);
      } catch (error) {
        if (isActive) {
          const detail = error instanceof Error ? error.message : String(error);
          console.warn('Categories feed unavailable:', detail);
        }
      }
    };

    hydrateCategories();

    return () => {
      isActive = false;
    };
  }, [isAuthenticated]);

  useEffect(() => {
    if (categoryCollection.length === 0) {
      return;
    }

    const hasActive = categoryCollection.some((category) => category.id === activeCategory);
    if (!hasActive) {
      setActiveCategory(categoryCollection[0].id);
    }
  }, [categoryCollection, activeCategory]);

  const categoryOptions = useMemo(() => {
    if (categoryCollection.length === 0) {
      return [];
    }

    const options = categoryCollection
      .map((category) => {
        const label = coalesceText(category.nameEn, category.name);
        return label
          ? {
            id: category.id,
            label,
          }
          : null;
      })
      .filter((category): category is { id: string; label: string } => category !== null);

    return options.length > 0 ? options : [];
  }, [categoryCollection]);


  const activeCategoryRecord = useMemo(() => {
    return categoryCollection.find((category) => category.id === activeCategory) ?? null;
  }, [categoryCollection, activeCategory]);

  const templateCommunityItems = useMemo(() => {
    if (!activeCategoryRecord) {
      return [];
    }

    return (activeCategoryRecord.templates ?? [])
      .map(translateTemplateToCommunity)
      .filter((item): item is CommunityItem => item !== null);
  }, [activeCategoryRecord]);

  const featureItems = useMemo(() => {
    return activityFeatures.map((item, index) => ({
      ...item,
      id: `${activeCategory}-${item.id || index}`,
    }));
  }, [activityFeatures]);

  const communityItems = useMemo(() => {
    const source: CommunityItem[] =
      templateCommunityItems.length > 0 ? templateCommunityItems : [];

    return source.map((item, index) => ({
      ...item,
      id: `${activeCategory}-${item.id || index}`,
    }));
  }, [activeCategory, templateCommunityItems]);

  const handleGeneratePress = (item: CommunityItem) => {
    requireAuth(() => {
      const templateId = item.id.split('-').pop() || item.id;
      router.push(`/templates/${templateId}`);
    });
  };

  const handleFeaturePress = (item: FeatureItemType) => {
    requireAuth(() => {
      console.log('用户已登录，使用功能:', item.title);
    });
  };

  return (
    <PageLayout backgroundColor="#050505">
      <ScrollView
        style={styles.scroll}
        contentContainerStyle={styles.contentContainer}
        showsVerticalScrollIndicator={false}
      >
        <StatusBarSpacer />
        <Header />
        <CategoryTabs categories={categoryOptions} activeId={activeCategory || ``} onChange={setActiveCategory} />
        {featureItems.length > 0 && <FeatureCarousel items={featureItems} onPress={handleFeaturePress} />}
        <SectionHeader title={activeCategoryRecord?.name || ``} />
        <CommunityGrid items={communityItems} onPressAction={handleGeneratePress} />
        <View style={styles.bottomSpacer} />
      </ScrollView>
    </PageLayout>
  );
}

const styles = StyleSheet.create({
  scroll: {
    flex: 1,
  },
  contentContainer: {
    paddingTop: 16,
    paddingBottom: 48,
  },
  bottomSpacer: {
    height: 32,
  },
});