const { Tenant, SubscriptionPlan, TenantSubscription, Apartment, Room, User } = require('../models');
const { Op } = require('sequelize');
const { logOperation } = require('../utils/logger');

const addCalendarMonths = (date, months) => {
  const source = new Date(date);
  const day = source.getDate();
  const target = new Date(source);
  target.setDate(1);
  target.setMonth(target.getMonth() + Number(months));

  const lastDayOfTargetMonth = new Date(target.getFullYear(), target.getMonth() + 1, 0).getDate();
  target.setDate(Math.min(day, lastDayOfTargetMonth));
  return target;
};

const getBillingCycle = (months) => {
  if (Number(months) === 12) return 'yearly';
  if (Number(months) === 1) return 'monthly';
  return 'custom';
};

const normalizeAmount = (value) => Number.parseFloat(Number(value || 0).toFixed(2));

const checkTenantExpiration = async () => {
  const now = new Date();

  const trialExpiredTenants = await Tenant.findAll({
    where: {
      billingStatus: 'trial_active',
      trialEndDate: { [Op.lt]: now }
    }
  });

  for (const tenant of trialExpiredTenants) {
    await tenant.update({ billingStatus: 'trial_expired' });
    await logOperation({
      tenantId: tenant.id,
      module: '计费管理',
      action: '试用期到期',
      description: `租户 ${tenant.code} 试用期已过期`,
      status: 'success'
    });
  }

  const paidExpiredTenants = await Tenant.findAll({
    where: {
      billingStatus: 'paid_active',
      paidEndDate: { [Op.lt]: now }
    }
  });

  for (const tenant of paidExpiredTenants) {
    await tenant.update({ billingStatus: 'paid_expired' });
    await TenantSubscription.update(
      { status: 'expired' },
      {
        where: {
          tenantId: tenant.id,
          status: 'active',
          endDate: { [Op.lt]: now }
        }
      }
    );
    await logOperation({
      tenantId: tenant.id,
      module: '计费管理',
      action: '付费期到期',
      description: `租户 ${tenant.code} 付费期已过期`,
      status: 'success'
    });
  }

  return {
    trialExpired: trialExpiredTenants.length,
    paidExpired: paidExpiredTenants.length,
    longExpired: 0
  };
};

const getUpcomingExpiredTenants = async (days = 7) => {
  const reminderDate = new Date();
  reminderDate.setDate(reminderDate.getDate() + days);

  return Tenant.findAll({
    where: {
      [Op.or]: [
        {
          billingStatus: 'trial_active',
          trialEndDate: {
            [Op.lte]: reminderDate,
            [Op.gte]: new Date()
          }
        },
        {
          billingStatus: 'paid_active',
          paidEndDate: {
            [Op.lte]: reminderDate,
            [Op.gte]: new Date()
          }
        }
      ]
    },
    include: [{
      model: SubscriptionPlan,
      as: 'subscriptionPlan'
    }]
  });
};

const calculateOverage = async (tenantId) => {
  const tenant = await Tenant.findByPk(tenantId, {
    include: [{
      model: SubscriptionPlan,
      as: 'subscriptionPlan'
    }]
  });

  if (!tenant) {
    throw new Error('租户不存在');
  }

  const [apartmentCount, roomCount, userCount] = await Promise.all([
    Apartment.count({ where: { tenantId, isDeleted: 0 } }),
    Room.count({ where: { tenantId, isDeleted: 0 } }),
    User.count({ where: { tenantId, isDeleted: 0 } })
  ]);

  return {
    usage: {
      apartments: apartmentCount,
      rooms: roomCount,
      users: userCount
    },
    limits: {
      apartments: tenant.maxApartments,
      rooms: tenant.maxRooms,
      users: tenant.maxUsers
    },
    overage: {
      apartments: Math.max(0, apartmentCount - tenant.maxApartments),
      rooms: Math.max(0, roomCount - tenant.maxRooms),
      users: Math.max(0, userCount - tenant.maxUsers)
    }
  };
};

const calculateRenewalAmount = async (tenantId, planId, months) => {
  const plan = await SubscriptionPlan.findOne({
    where: { id: planId, status: 'active', isDeleted: 0 }
  });

  if (!plan) {
    throw new Error('套餐不存在或已停用');
  }

  const normalizedMonths = Number.parseInt(months, 10);
  if (!Number.isInteger(normalizedMonths) || normalizedMonths < 1 || normalizedMonths > 36) {
    throw new Error('购买月数必须在1-36之间');
  }

  const billingCycle = getBillingCycle(normalizedMonths);
  const monthlyPrice = Number(plan.monthlyPrice || 0);
  const yearlyPrice = Number(plan.yearlyPrice || 0);
  const baseAmount = billingCycle === 'yearly' && yearlyPrice > 0
    ? yearlyPrice
    : monthlyPrice * normalizedMonths;

  return {
    baseAmount: normalizeAmount(baseAmount),
    overageAmount: 0,
    discountAmount: 0,
    totalAmount: normalizeAmount(baseAmount),
    billingCycle,
    details: {
      planName: plan.name,
      monthlyPrice: normalizeAmount(monthlyPrice),
      yearlyPrice: normalizeAmount(yearlyPrice),
      months: normalizedMonths,
      billingCycle
    }
  };
};

const processPaymentSuccess = async ({ order, payment, operatorId, transaction }) => {
  const tenant = await Tenant.findByPk(order.tenantId, { transaction });
  if (!tenant) {
    throw new Error('租户不存在');
  }

  const plan = await SubscriptionPlan.findByPk(order.planId, { transaction });
  if (!plan) {
    throw new Error('套餐不存在');
  }

  const now = new Date();
  const currentEnd = tenant.paidEndDate ? new Date(tenant.paidEndDate) : null;
  const startDate = tenant.billingStatus === 'paid_active' && currentEnd && currentEnd > now
    ? currentEnd
    : now;
  const endDate = addCalendarMonths(startDate, order.months);
  const billingCycle = order.billingCycle || getBillingCycle(order.months);

  await TenantSubscription.update(
    { status: 'expired' },
    {
      where: {
        tenantId: tenant.id,
        status: 'active',
        isDeleted: 0
      },
      transaction
    }
  );

  const subscription = await TenantSubscription.create({
    tenantId: tenant.id,
    planId: plan.id,
    orderId: order.id,
    status: 'active',
    billingCycle,
    months: order.months,
    startDate,
    endDate,
    amount: order.actualAmount,
    createBy: operatorId,
    updateBy: operatorId
  }, { transaction });

  await tenant.update({
    planId: plan.id,
    billingStatus: 'paid_active',
    paidStartDate: startDate,
    paidEndDate: endDate,
    currentPeriodStart: startDate,
    currentPeriodEnd: endDate,
    maxApartments: plan.maxApartments,
    maxRooms: plan.maxRooms,
    maxUsers: plan.maxUsers,
    updateBy: operatorId
  }, { transaction });

  await order.update({
    subscriptionId: subscription.id,
    periodStart: startDate,
    periodEnd: endDate
  }, { transaction });

  await logOperation({
    tenantId: tenant.id,
    userId: operatorId,
    module: '计费管理',
    action: '订阅生效',
    description: `租户订阅 ${plan.name} ${order.months} 个月，有效期至 ${endDate.toLocaleDateString()}`,
    status: 'success'
  });

  return {
    subscription,
    billingStatus: 'paid_active',
    paidStartDate: startDate,
    paidEndDate: endDate,
    paymentId: payment ? payment.id : null
  };
};

module.exports = {
  checkTenantExpiration,
  getUpcomingExpiredTenants,
  calculateOverage,
  calculateRenewalAmount,
  processPaymentSuccess
};