'use client';

import { useState } from 'react';
import { motion } from 'framer-motion';
import { Wallet, CreditCard, Plus, Check, Zap, Crown, Building2, ArrowRight, Receipt, Download, Clock } from 'lucide-react';
import { useAuth } from '@/lib/contexts/AuthContext';

interface Plan {
  id: string;
  name: string;
  price: number;
  priceMonthly: number;
  icon: React.ElementType;
  color: string;
  features: string[];
  limits: {
    apiRequests: string;
    llmRequests: string;
    storage: string;
  };
}

const plans: Plan[] = [
  {
    id: 'free',
    name: 'Free',
    price: 0,
    priceMonthly: 0,
    icon: Zap,
    color: 'text-muted',
    features: ['Базовый поиск', 'История запросов', 'Ограниченный AI'],
    limits: {
      apiRequests: '1,000/день',
      llmRequests: '50/день',
      storage: '100 MB',
    },
  },
  {
    id: 'pro',
    name: 'Pro',
    price: 990,
    priceMonthly: 990,
    icon: Crown,
    color: 'text-accent',
    features: ['Расширенный поиск', 'Приоритетный AI', 'Экспорт данных', 'API доступ'],
    limits: {
      apiRequests: '10,000/день',
      llmRequests: '500/день',
      storage: '1 GB',
    },
  },
  {
    id: 'business',
    name: 'Business',
    price: 4990,
    priceMonthly: 4990,
    icon: Building2,
    color: 'text-amber-600',
    features: ['Всё из Pro', 'Безлимитный AI', 'Приоритетная поддержка', 'Команды', 'SLA 99.9%'],
    limits: {
      apiRequests: '100,000/день',
      llmRequests: '5,000/день',
      storage: '10 GB',
    },
  },
];

const mockTransactions = [
  { id: '1', date: '2026-02-28', amount: 990, type: 'subscription', description: 'Подписка Pro' },
  { id: '2', date: '2026-02-15', amount: 500, type: 'topup', description: 'Пополнение баланса' },
  { id: '3', date: '2026-01-28', amount: 990, type: 'subscription', description: 'Подписка Pro' },
];

export function BillingTab() {
  const { user } = useAuth();
  const [selectedPlan, setSelectedPlan] = useState<string | null>(null);
  const [showTopup, setShowTopup] = useState(false);
  const [topupAmount, setTopupAmount] = useState('');

  if (!user) return null;

  const currentPlan = plans.find(p => p.id === user.tier) || plans[0];

  const handleUpgrade = (planId: string) => {
    setSelectedPlan(planId);
  };

  const handleTopup = () => {
    const amount = parseInt(topupAmount, 10);
    if (isNaN(amount) || amount < 100) return;
    setShowTopup(false);
    setTopupAmount('');
  };

  return (
    <div className="space-y-6">
      {/* Balance Card */}
      <Section title="Баланс" icon={Wallet}>
        <div className="p-4 bg-gradient-to-br from-accent/20 via-accent/10 to-transparent border border-accent/30 rounded-xl">
          <div className="flex items-center justify-between">
            <div>
              <p className="text-sm text-muted">Текущий баланс</p>
              <p className="text-3xl font-bold text-primary mt-1">{(user.balance ?? 0).toLocaleString('ru-RU')} ₽</p>
            </div>
            <button
              onClick={() => setShowTopup(!showTopup)}
              className="flex items-center gap-2 px-4 py-2.5 bg-accent text-white rounded-xl hover:bg-accent-hover transition-all text-sm font-medium"
            >
              <Plus className="w-4 h-4" />
              Пополнить
            </button>
          </div>
          
          {showTopup && (
            <motion.div
              initial={{ opacity: 0, height: 0 }}
              animate={{ opacity: 1, height: 'auto' }}
              className="mt-4 pt-4 border-t border-accent/20"
            >
              <div className="flex gap-2 mb-3">
                {[100, 500, 1000, 5000].map((amount) => (
                  <button
                    key={amount}
                    onClick={() => setTopupAmount(amount.toString())}
                    className={`flex-1 py-2 rounded-lg text-sm font-medium transition-all ${
                      topupAmount === amount.toString()
                        ? 'bg-accent text-white'
                        : 'bg-surface/50 text-secondary hover:text-primary hover:bg-surface'
                    }`}
                  >
                    {amount} ₽
                  </button>
                ))}
              </div>
              <div className="flex gap-2">
                <input
                  type="number"
                  value={topupAmount}
                  onChange={(e) => setTopupAmount(e.target.value)}
                  placeholder="Сумма"
                  className="flex-1 px-3 py-2 bg-surface border border-border rounded-lg text-sm text-primary focus:outline-none focus:border-accent"
                />
                <button
                  onClick={handleTopup}
                  disabled={!topupAmount || parseInt(topupAmount, 10) < 100}
                  className="px-4 py-2 bg-accent text-white rounded-lg text-sm font-medium hover:bg-accent-hover transition-all disabled:opacity-50"
                >
                  Оплатить
                </button>
              </div>
              <p className="text-xs text-muted mt-2">Минимальная сумма: 100 ₽</p>
            </motion.div>
          )}
        </div>
      </Section>

      {/* Current Plan */}
      <Section title="Текущий тариф" icon={currentPlan.icon}>
        <div className="p-4 bg-elevated/40 border border-border/40 rounded-xl">
          <div className="flex items-center justify-between mb-4">
            <div className="flex items-center gap-3">
              <div className={`w-10 h-10 rounded-xl bg-surface flex items-center justify-center ${currentPlan.color}`}>
                <currentPlan.icon className="w-5 h-5" />
              </div>
              <div>
                <h3 className="font-medium text-primary">{currentPlan.name}</h3>
                <p className="text-sm text-muted">
                  {currentPlan.price === 0 ? 'Бесплатно' : `${currentPlan.price.toLocaleString('ru-RU')} ₽/мес`}
                </p>
              </div>
            </div>
            {user.tier !== 'business' && (
              <button
                onClick={() => handleUpgrade(user.tier === 'free' ? 'pro' : 'business')}
                className="flex items-center gap-1.5 px-3 py-1.5 bg-accent/10 text-accent rounded-lg text-sm font-medium hover:bg-accent/20 transition-all"
              >
                Улучшить
                <ArrowRight className="w-4 h-4" />
              </button>
            )}
          </div>
          <div className="grid grid-cols-3 gap-3">
            <div className="p-3 bg-surface/30 rounded-lg">
              <p className="text-xs text-muted">API запросы</p>
              <p className="text-sm font-medium text-primary mt-0.5">{currentPlan.limits.apiRequests}</p>
            </div>
            <div className="p-3 bg-surface/30 rounded-lg">
              <p className="text-xs text-muted">AI запросы</p>
              <p className="text-sm font-medium text-primary mt-0.5">{currentPlan.limits.llmRequests}</p>
            </div>
            <div className="p-3 bg-surface/30 rounded-lg">
              <p className="text-xs text-muted">Хранилище</p>
              <p className="text-sm font-medium text-primary mt-0.5">{currentPlan.limits.storage}</p>
            </div>
          </div>
        </div>
      </Section>

      {/* Plans Comparison */}
      {selectedPlan && (
        <Section title="Выбор тарифа" icon={Crown}>
          <div className="grid grid-cols-1 sm:grid-cols-3 gap-4">
            {plans.map((plan) => (
              <motion.div
                key={plan.id}
                initial={{ opacity: 0, y: 10 }}
                animate={{ opacity: 1, y: 0 }}
                className={`p-4 rounded-xl border transition-all cursor-pointer ${
                  selectedPlan === plan.id
                    ? 'bg-accent/10 border-accent'
                    : 'bg-elevated/40 border-border/40 hover:border-border'
                } ${user.tier === plan.id ? 'ring-2 ring-accent/50' : ''}`}
                onClick={() => setSelectedPlan(plan.id)}
              >
                <div className="flex items-center gap-2 mb-3">
                  <plan.icon className={`w-5 h-5 ${plan.color}`} />
                  <span className="font-medium text-primary">{plan.name}</span>
                  {user.tier === plan.id && (
                    <span className="text-xs bg-accent/20 text-accent px-1.5 py-0.5 rounded">Текущий</span>
                  )}
                </div>
                <p className="text-2xl font-bold text-primary mb-3">
                  {plan.price === 0 ? 'Бесплатно' : `${plan.price.toLocaleString('ru-RU')} ₽`}
                  {plan.price > 0 && <span className="text-sm font-normal text-muted">/мес</span>}
                </p>
                <ul className="space-y-2">
                  {plan.features.map((feature, idx) => (
                    <li key={idx} className="flex items-center gap-2 text-sm text-secondary">
                      <Check className="w-4 h-4 text-accent flex-shrink-0" />
                      {feature}
                    </li>
                  ))}
                </ul>
                {user.tier !== plan.id && plan.id !== 'free' && (
                  <button
                    onClick={(e) => { e.stopPropagation(); handleUpgrade(plan.id); }}
                    className="w-full mt-4 py-2 bg-accent text-white rounded-lg text-sm font-medium hover:bg-accent-hover transition-all"
                  >
                    {plans.findIndex(p => p.id === user.tier) < plans.findIndex(p => p.id === plan.id) ? 'Улучшить' : 'Выбрать'}
                  </button>
                )}
              </motion.div>
            ))}
          </div>
        </Section>
      )}

      {/* Payment Methods */}
      <Section title="Способы оплаты" icon={CreditCard}>
        <div className="p-4 bg-elevated/40 border border-border/40 rounded-xl">
          <div className="flex items-center justify-between">
            <div className="flex items-center gap-3">
              <div className="w-10 h-10 rounded-xl bg-surface flex items-center justify-center">
                <CreditCard className="w-5 h-5 text-muted" />
              </div>
              <p className="text-sm text-muted">Карты не добавлены</p>
            </div>
            <button className="flex items-center gap-1.5 px-3 py-1.5 bg-surface border border-border text-secondary rounded-lg text-sm hover:text-primary hover:border-border/80 transition-all">
              <Plus className="w-4 h-4" />
              Добавить
            </button>
          </div>
        </div>
      </Section>

      {/* Transaction History */}
      <Section title="История платежей" icon={Receipt}>
        <div className="space-y-2">
          {mockTransactions.length === 0 ? (
            <div className="p-4 bg-elevated/40 border border-border/40 rounded-xl text-center">
              <Clock className="w-8 h-8 text-muted mx-auto mb-2" />
              <p className="text-sm text-muted">История платежей пуста</p>
            </div>
          ) : (
            mockTransactions.map((tx) => (
              <div
                key={tx.id}
                className="flex items-center justify-between p-3 bg-elevated/40 border border-border/40 rounded-xl"
              >
                <div className="flex items-center gap-3">
                  <div className={`w-8 h-8 rounded-lg flex items-center justify-center ${
                    tx.type === 'topup' ? 'bg-success/10' : 'bg-accent/10'
                  }`}>
                    {tx.type === 'topup' ? (
                      <Plus className="w-4 h-4 text-success" />
                    ) : (
                      <Receipt className="w-4 h-4 text-accent" />
                    )}
                  </div>
                  <div>
                    <p className="text-sm text-primary">{tx.description}</p>
                    <p className="text-xs text-muted">{new Date(tx.date).toLocaleDateString('ru-RU')}</p>
                  </div>
                </div>
                <div className="flex items-center gap-3">
                  <span className={`text-sm font-medium ${tx.type === 'topup' ? 'text-success' : 'text-primary'}`}>
                    {tx.type === 'topup' ? '+' : '-'}{tx.amount.toLocaleString('ru-RU')} ₽
                  </span>
                  <button className="p-1.5 text-muted hover:text-secondary transition-colors">
                    <Download className="w-4 h-4" />
                  </button>
                </div>
              </div>
            ))
          )}
        </div>
      </Section>
    </div>
  );
}

function Section({ title, icon: Icon, children }: { title: string; icon: React.ElementType; children: React.ReactNode }) {
  return (
    <motion.div
      initial={{ opacity: 0, y: 8 }}
      animate={{ opacity: 1, y: 0 }}
      className="space-y-3"
    >
      <div className="flex items-center gap-2">
        <Icon className="w-4 h-4 text-muted" />
        <h2 className="text-xs font-semibold text-muted uppercase tracking-wider">{title}</h2>
      </div>
      {children}
    </motion.div>
  );
}