import { useState, useEffect, useRef, useMemo } from 'react';
import { Linking } from 'react-native';
import { useRouter } from 'expo-router';
import { authClient, useSession } from '@/lib/auth/client';
import { getStripePlans, getPlanNames } from '@/lib/api/pricing';
import { Alert } from '@/utils/alert';
import type {
  StripePricingTableResponse,
  CreditPlan,
} from '@/lib/api/pricing';

export function usePricing() {
  const router = useRouter();
  const { data: session, isPending: isAuthPending } = useSession();
  const [selectedPlanIndex, setSelectedPlanIndex] = useState(0);

  // Stripe 套餐数据
  const [stripePricingData, setStripePricingData] = useState<StripePricingTableResponse | null>(null);
  const [isStripePricingLoading, setIsStripePricingLoading] = useState(true);
  const [stripePricingError, setStripePricingError] = useState<string | null>(null);

  // 订阅数据
  const [authSubscriptions, setAuthSubscriptions] = useState<any[]>([]);
  const [isLoadingSubscriptions, setIsLoadingSubscriptions] = useState(false);
  const [isFetchingSubscriptions, setIsFetchingSubscriptions] = useState(false);

  // Mutation 状态
  const [createSubscriptionPending, setCreateSubscriptionPending] = useState(false);
  const [upgradeSubscriptionPending, setUpgradeSubscriptionPending] = useState(false);
  const [restoreSubscriptionPending, setRestoreSubscriptionPending] = useState(false);
  const [rechargeTokenPending, setRechargeTokenPending] = useState(false);

  const isInitialized = useRef(false);

  // 获取 Stripe 套餐数据
  useEffect(() => {
    const fetchStripePlans = async () => {
      setIsStripePricingLoading(true);
      const result = await getStripePlans();

      if (result.success && result.data) {
        setStripePricingData(result.data);
        setStripePricingError(null);
      } else {
        setStripePricingError(result.message || 'Failed to load pricing');
      }

      setIsStripePricingLoading(false);
    };

    fetchStripePlans();
  }, []);

  // 获取订阅数据
  const fetchAuthSubscriptions = async () => {
    if (!session?.user?.id) return;

    setIsFetchingSubscriptions(true);
    try {
      const { data, error } = await authClient.subscription.list({
        query: {
          referenceId: session?.user?.id || '',
        },
      });

      if (!error && data) {
        setAuthSubscriptions(data);
      }
    } catch (error) {
      console.error('Failed to fetch subscriptions:', error);
    } finally {
      setIsFetchingSubscriptions(false);
    }
  };

  useEffect(() => {
    if (session?.user?.id) {
      setIsLoadingSubscriptions(true);
      fetchAuthSubscriptions().finally(() => {
        setIsLoadingSubscriptions(false);
      });
    }
  }, [session?.user?.id]);

  // 订阅类型分类
  const licensedSubscriptions = authSubscriptions?.filter((sub: any) => sub.type === 'licenced') || [];
  const meteredSubscriptions = authSubscriptions?.filter((sub: any) => sub.type === 'metered') || [];

  // 订阅状态计算
  const activeAuthSubscription = licensedSubscriptions?.find(
    (sub: any) => sub.status === 'active' || sub.status === 'trialing'
  );

  const hasActiveSubscription = !!(
    activeAuthSubscription &&
    activeAuthSubscription.cancelAtPeriodEnd === false &&
    activeAuthSubscription.status === 'active'
  );

  const hasCanceledButActiveSubscription = !!(
    activeAuthSubscription &&
    activeAuthSubscription.status === 'active' &&
    activeAuthSubscription.cancelAtPeriodEnd === true
  );

  // 获取价格计划
  const creditPlans = useMemo((): CreditPlan[] => {
    if (stripePricingData?.pricing_table_items) {
      return stripePricingData.pricing_table_items
        .filter((item) => item.recurring?.interval === 'month')
        .map((item) => {
          const amountInCents = parseInt(item.amount);
          const credits = item.metadata?.grant_token || amountInCents;
          return {
            amountInCents,
            credits,
            popular: item.is_highlight || item.highlight_text === 'most_popular',
          };
        });
    }
    return [];
  }, [stripePricingData?.pricing_table_items]);

  // 当前订阅对应的积分
  const currentSubscriptionCredits = useMemo((): number | null => {
    if (!activeAuthSubscription?.plan) return null;

    const planNameLower = activeAuthSubscription.plan.toLowerCase();
    const planNames = getPlanNames(stripePricingData);
    const matchingPlan = creditPlans.find((_, index) => {
      return planNames[index]?.toLowerCase() === planNameLower;
    });
    return matchingPlan?.credits || null;
  }, [activeAuthSubscription?.plan, creditPlans, stripePricingData]);

  // 积分余额
  const creditBalanceData = meteredSubscriptions?.[0]?.creditBalance;
  const creditBalance = creditBalanceData?.remainingTokenBalance || 0;

  const selectedPlan = creditPlans[selectedPlanIndex] || creditPlans[0];

  // 初始化选中的计划
  useEffect(() => {
    const hasRequiredData = creditPlans.length > 0 && !isStripePricingLoading && !isLoadingSubscriptions;

    if (!isInitialized.current && hasRequiredData) {
      let targetIndex = Math.floor(creditPlans.length / 2);

      if (currentSubscriptionCredits) {
        const foundIndex = creditPlans.findIndex(plan => plan.credits.toString() === currentSubscriptionCredits.toString());
        if (foundIndex !== -1) {
          targetIndex = foundIndex;
        }
      }

      setSelectedPlanIndex(targetIndex);
      isInitialized.current = true;
    }
  }, [currentSubscriptionCredits, creditPlans, isStripePricingLoading, isLoadingSubscriptions]);

  // 创建订阅
  const createSubscription = async (priceId: string, productId: string) => {
    setCreateSubscriptionPending(true);
    try {
      const { data, error } = await authClient.subscription.create({
        priceId,
        productId,
        successUrl: 'bestaibest://exchange',
        cancelUrl: 'bestaibest://exchange?canceled=true',
      });

      if (error) {
        Alert.alert('Error', error.message || 'Failed to create subscription');
        return null;
      }

      if (data?.url) {
        await Linking.openURL(data.url);
      }

      return data;
    } catch (error) {
      Alert.alert('Error', 'Failed to create subscription');
      return null;
    } finally {
      setCreateSubscriptionPending(false);
    }
  };

  // 升级订阅
  const upgradeSubscription = async (credits: number) => {
    if (!activeAuthSubscription?.stripeSubscriptionId) {
      Alert.alert('Error', 'No active subscription found');
      return null;
    }

    setUpgradeSubscriptionPending(true);
    try {
      const planIndex = creditPlans.findIndex(plan => plan.credits === credits);
      const planNames = getPlanNames(stripePricingData);
      const planName = planNames[planIndex] || 'basic';

      const { data, error } = await authClient.subscription.upgrade({
        plan: planName,
        subscriptionId: activeAuthSubscription.stripeSubscriptionId,
        successUrl: 'bestaibest://exchange',
        cancelUrl: 'bestaibest://exchange?canceled=true',
      });

      if (error) {
        Alert.alert('Error', error.message || 'Failed to upgrade subscription');
        return null;
      }

      if (data?.url) {
        await Linking.openURL(data.url);
      }

      return data;
    } catch (error) {
      Alert.alert('Error', 'Failed to upgrade subscription');
      return null;
    } finally {
      setUpgradeSubscriptionPending(false);
    }
  };

  // 恢复订阅
  const restoreSubscription = async () => {
    if (!activeAuthSubscription) {
      Alert.alert('Error', 'No subscription to restore');
      return null;
    }

    setRestoreSubscriptionPending(true);
    try {
      const { data, error } = await authClient.subscription.restore({
        subscriptionId: activeAuthSubscription.stripeSubscriptionId,
        referenceId: activeAuthSubscription.referenceId,
      });

      if (error) {
        Alert.alert('Error', error.message || 'Failed to restore subscription');
        return null;
      }

      Alert.alert('Success', 'Subscription restored successfully');
      await fetchAuthSubscriptions();
      return data;
    } catch (error) {
      Alert.alert('Error', 'Failed to restore subscription');
      return null;
    } finally {
      setRestoreSubscriptionPending(false);
    }
  };

  // 充值 Token
  const rechargeToken = async (amount: number) => {
    if (!amount || amount <= 0) {
      Alert.alert('Error', 'Invalid recharge amount');
      return null;
    }

    // 检查 pricing data 是否加载完成
    if (!stripePricingData?.pricing_table_items?.[0]?.metered_price_id) {
      Alert.alert('Error', 'Pricing data not available. Please try again later.');
      return null;
    }

    // 检查用户是否有 metered subscription
    if (!meteredSubscriptions || meteredSubscriptions.length === 0 || !meteredSubscriptions[0]?.priceId) {
      Alert.alert('Error', 'No active metered subscription found. Please contact support.');
      return null;
    }

    setRechargeTokenPending(true);
    try {
      const { data, error } = await authClient.subscription.credit.topup({
        amount: amount,
        priceId: meteredSubscriptions[0].priceId,
        successUrl: 'bestaibest://exchange',
        cancelUrl: 'bestaibest://exchange?canceled=true',
      });

      if (error) {
        Alert.alert('Error', error.message || 'Failed to recharge');
        return null;
      }

      if (data?.url) {
        await Linking.openURL(data.url);
      }

      return data;
    } catch (error) {
      Alert.alert('Error', 'Failed to recharge');
      return null;
    } finally {
      setRechargeTokenPending(false);
    }
  };

  // 处理订阅操作
  const handleSubscriptionAction = async (planIndexOverride?: number) => {
    const targetPlanIndex = planIndexOverride !== undefined ? planIndexOverride : selectedPlanIndex;
    const targetPlan = creditPlans[targetPlanIndex];

    if (!targetPlan) {
      Alert.alert('Error', 'Invalid plan selected');
      return;
    }

    if (isStripePricingLoading) {
      Alert.alert('Please wait', 'Loading pricing data...');
      return;
    }

    // 如果选择的是当前订阅
    if (hasActiveSubscription && currentSubscriptionCredits === targetPlan.credits) {
      return;
    }

    // 如果是已取消但仍活跃的订阅
    if (hasCanceledButActiveSubscription && currentSubscriptionCredits === targetPlan.credits) {
      await restoreSubscription();
      return;
    }

    const pricingItem = stripePricingData?.pricing_table_items?.[targetPlanIndex];
    if (!pricingItem) {
      Alert.alert('Error', 'Plan not found');
      return;
    }

    // 判断创建还是升级
    if (hasActiveSubscription || hasCanceledButActiveSubscription) {
      await upgradeSubscription(targetPlan.credits);
    } else {
      await createSubscription(pricingItem.price_id, pricingItem.product_id);
    }
  };

  // 格式化积分
  const formatCredits = (credits: number) => {
    return credits.toLocaleString();
  };

  // 综合加载状态
  const isDataFullyLoaded = useMemo(() => {
    if (isAuthPending) return false;
    if (!session) return !isStripePricingLoading;
    return !isStripePricingLoading && !isLoadingSubscriptions;
  }, [session, isAuthPending, isStripePricingLoading, isLoadingSubscriptions]);

  return {
    // 状态
    selectedPlanIndex,
    selectedPlan,
    creditPlans,
    // 认证状态
    session,
    isAuthPending,
    isDataFullyLoaded,
    // 订阅状态
    activeAuthSubscription,
    hasActiveSubscription,
    hasCanceledButActiveSubscription,
    currentSubscriptionCredits,
    isLoadingSubscriptions,
    isFetchingSubscriptions,
    meteredSubscriptions,
    // Credits 余额
    creditBalance,
    creditBalanceData,
    // Stripe 数据
    stripePricingData,
    isStripePricingLoading,
    stripePricingError,
    // 操作方法
    setSelectedPlanIndex,
    handleSubscriptionAction,
    fetchAuthSubscriptions,
    rechargeToken,
    // 工具方法
    formatCredits,
    // Mutation 状态
    createSubscriptionPending,
    upgradeSubscriptionPending,
    restoreSubscriptionPending,
    rechargeTokenPending,
  };
}