'use client';

import { useEffect, useState } from 'react';
import { Badge } from '@/components/ui/badge';
import { Button } from '@/components/ui/button';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from '@/components/ui/dialog';
import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
import {
  subscriptionApi,
  type BillingHistoryDto,
  type PlanDto,
  type QuotaCheckResult,
} from '@/lib/subscription-api';

function formatVND(amount: string | number): string {
  const num = typeof amount === 'string' ? Number(amount) : amount;
  if (num === 0) return 'Miễn phí';
  if (num >= 1_000_000) return `${(num / 1_000_000).toFixed(0)} triệu đ`;
  return num.toLocaleString('vi-VN') + ' đ';
}

const PLAN_TIER_ORDER = ['FREE', 'AGENT_PRO', 'INVESTOR', 'ENTERPRISE'];
const PLAN_TIER_LABELS: Record<string, string> = {
  FREE: 'Miễn phí',
  AGENT_PRO: 'Môi giới Pro',
  INVESTOR: 'Nhà đầu tư',
  ENTERPRISE: 'Doanh nghiệp',
};

const STATUS_MAP: Record<string, { label: string; variant: 'default' | 'secondary' | 'destructive' | 'outline' }> = {
  ACTIVE: { label: 'Đang hoạt động', variant: 'default' },
  PAST_DUE: { label: 'Quá hạn', variant: 'destructive' },
  CANCELLED: { label: 'Đã hủy', variant: 'outline' },
  EXPIRED: { label: 'Hết hạn', variant: 'secondary' },
};

export default function SubscriptionPage() {
  const [plans, setPlans] = useState<PlanDto[]>([]);
  const [billing, setBilling] = useState<BillingHistoryDto | null>(null);
  const [quotas, setQuotas] = useState<QuotaCheckResult[]>([]);
  const [loading, setLoading] = useState(true);
  const [upgradeTarget, setUpgradeTarget] = useState<PlanDto | null>(null);
  const [billingCycle, setBillingCycle] = useState<'monthly' | 'yearly'>('monthly');
  const [processing, setProcessing] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [activeTab, setActiveTab] = useState('plan');

  useEffect(() => {
    setLoading(true);
    Promise.all([
      subscriptionApi.getPlans().catch(() => []),
      subscriptionApi.getBillingHistory().catch(() => null),
      Promise.all([
        subscriptionApi.checkQuota('listings').catch(() => null),
        subscriptionApi.checkQuota('saved_searches').catch(() => null),
      ]),
    ])
      .then(([plansData, billingData, quotaResults]) => {
        setPlans(plansData.sort((a, b) => PLAN_TIER_ORDER.indexOf(a.tier) - PLAN_TIER_ORDER.indexOf(b.tier)));
        setBilling(billingData);
        setQuotas(quotaResults.filter((q): q is QuotaCheckResult => q !== null));
      })
      .finally(() => setLoading(false));
  }, []);

  const currentTier = billing?.subscription?.planTier ?? 'FREE';
  const currentTierIndex = PLAN_TIER_ORDER.indexOf(currentTier);
  const subStatus = billing?.subscription?.status
    ? STATUS_MAP[billing.subscription.status] ?? { label: 'Đang hoạt động', variant: 'default' as const }
    : null;

  const handleUpgrade = async () => {
    if (!upgradeTarget) return;
    setProcessing(true);
    setError(null);
    try {
      if (billing?.subscription) {
        await subscriptionApi.upgradeSubscription(upgradeTarget.tier);
      } else {
        await subscriptionApi.createSubscription(upgradeTarget.tier, billingCycle);
      }
      // Reload billing data
      const newBilling = await subscriptionApi.getBillingHistory().catch(() => null);
      setBilling(newBilling);
      setUpgradeTarget(null);
    } catch (e) {
      setError(e instanceof Error ? e.message : 'Nâng cấp thất bại');
    } finally {
      setProcessing(false);
    }
  };

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-3xl font-bold">Gói dịch vụ</h1>
        <p className="mt-2 text-muted-foreground">
          Quản lý gói đăng ký và theo dõi hạn mức sử dụng
        </p>
      </div>

      {error && (
        <div className="rounded-lg border border-red-200 bg-red-50 p-4 text-sm text-red-700">
          {error}
          <button onClick={() => setError(null)} className="ml-2 font-medium underline">
            Đóng
          </button>
        </div>
      )}

      {loading ? (
        <div className="flex h-64 items-center justify-center text-muted-foreground">
          Đang tải...
        </div>
      ) : (
        <Tabs value={activeTab} onValueChange={setActiveTab}>
          <TabsList>
            <TabsTrigger value="plan">Gói hiện tại</TabsTrigger>
            <TabsTrigger value="plans">So sánh gói</TabsTrigger>
            <TabsTrigger value="history">Lịch sử thanh toán</TabsTrigger>
          </TabsList>

          {/* Current plan tab */}
          <TabsContent value="plan" className="space-y-6">
            <Card>
              <CardHeader>
                <div className="flex items-center justify-between">
                  <div>
                    <CardTitle className="text-lg">
                      Gói {PLAN_TIER_LABELS[currentTier] ?? currentTier}
                    </CardTitle>
                    <CardDescription>
                      {billing?.subscription
                        ? `Kỳ hiện tại: ${new Date(billing.subscription.currentPeriodStart).toLocaleDateString('vi-VN')} — ${new Date(billing.subscription.currentPeriodEnd).toLocaleDateString('vi-VN')}`
                        : 'Bạn đang sử dụng gói miễn phí'}
                    </CardDescription>
                  </div>
                  {subStatus && <Badge variant={subStatus.variant}>{subStatus.label}</Badge>}
                </div>
              </CardHeader>
              <CardContent>
                {/* Quota usage */}
                {quotas.length > 0 && (
                  <div className="space-y-4">
                    <h3 className="font-semibold">Hạn mức sử dụng</h3>
                    {quotas.map((q) => {
                      const pct = q.limit > 0 ? (q.used / q.limit) * 100 : 0;
                      return (
                        <div key={q.metric} className="space-y-1">
                          <div className="flex justify-between text-sm">
                            <span className="text-muted-foreground">
                              {q.metric === 'listings' ? 'Tin đăng' : q.metric === 'saved_searches' ? 'Tìm kiếm đã lưu' : q.metric}
                            </span>
                            <span>
                              {q.used}/{q.limit}
                            </span>
                          </div>
                          <div className="h-2 w-full rounded-full bg-muted">
                            <div
                              className={`h-2 rounded-full ${pct > 90 ? 'bg-red-500' : pct > 70 ? 'bg-yellow-500' : 'bg-primary'}`}
                              style={{ width: `${Math.min(pct, 100)}%` }}
                            />
                          </div>
                        </div>
                      );
                    })}
                  </div>
                )}
              </CardContent>
            </Card>
          </TabsContent>

          {/* Plan comparison tab */}
          <TabsContent value="plans" className="space-y-6">
            {/* Billing cycle toggle */}
            <div className="flex items-center justify-center gap-3">
              <Button
                variant={billingCycle === 'monthly' ? 'default' : 'outline'}
                size="sm"
                onClick={() => setBillingCycle('monthly')}
              >
                Theo tháng
              </Button>
              <Button
                variant={billingCycle === 'yearly' ? 'default' : 'outline'}
                size="sm"
                onClick={() => setBillingCycle('yearly')}
              >
                Theo năm
                <Badge variant="secondary" className="ml-2">
                  -17%
                </Badge>
              </Button>
            </div>

            <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
              {plans.map((plan) => {
                const tierIndex = PLAN_TIER_ORDER.indexOf(plan.tier);
                const isCurrent = plan.tier === currentTier;
                const isUpgrade = tierIndex > currentTierIndex;
                const price = billingCycle === 'monthly' ? plan.priceMonthlyVND : plan.priceYearlyVND;

                return (
                  <Card
                    key={plan.id}
                    className={isCurrent ? 'border-primary ring-1 ring-primary' : ''}
                  >
                    <CardHeader>
                      <CardTitle className="text-lg">
                        {PLAN_TIER_LABELS[plan.tier] ?? plan.name}
                      </CardTitle>
                      <CardDescription>
                        <span className="text-2xl font-bold text-foreground">
                          {formatVND(price)}
                        </span>
                        {Number(price) > 0 && (
                          <span className="text-sm">
                            /{billingCycle === 'monthly' ? 'tháng' : 'năm'}
                          </span>
                        )}
                      </CardDescription>
                    </CardHeader>
                    <CardContent className="space-y-3">
                      <div className="space-y-2 text-sm">
                        <div className="flex justify-between">
                          <span className="text-muted-foreground">Tin đăng</span>
                          <span className="font-medium">
                            {plan.maxListings === -1 ? 'Không giới hạn' : plan.maxListings}
                          </span>
                        </div>
                        <div className="flex justify-between">
                          <span className="text-muted-foreground">Tìm kiếm lưu</span>
                          <span className="font-medium">
                            {plan.maxSavedSearches === -1
                              ? 'Không giới hạn'
                              : plan.maxSavedSearches}
                          </span>
                        </div>
                        {plan.features &&
                          Object.entries(plan.features).map(([key, val]) => (
                            <div key={key} className="flex justify-between">
                              <span className="text-muted-foreground">{key}</span>
                              <span className="font-medium">
                                {typeof val === 'boolean' ? (val ? '✓' : '✗') : String(val)}
                              </span>
                            </div>
                          ))}
                      </div>

                      {isCurrent ? (
                        <Button variant="outline" className="w-full" disabled>
                          Gói hiện tại
                        </Button>
                      ) : isUpgrade ? (
                        <Button className="w-full" onClick={() => setUpgradeTarget(plan)}>
                          Nâng cấp
                        </Button>
                      ) : (
                        <Button variant="outline" className="w-full" disabled>
                          —
                        </Button>
                      )}
                    </CardContent>
                  </Card>
                );
              })}
            </div>
          </TabsContent>

          {/* Payment history tab */}
          <TabsContent value="history">
            <Card>
              <CardHeader>
                <CardTitle className="text-lg">Lịch sử thanh toán</CardTitle>
                <CardDescription>Các giao dịch liên quan đến gói dịch vụ</CardDescription>
              </CardHeader>
              <CardContent>
                {!billing || billing.payments.length === 0 ? (
                  <div className="flex h-32 items-center justify-center text-muted-foreground">
                    Chưa có giao dịch nào
                  </div>
                ) : (
                  <div className="space-y-3">
                    {billing.payments.map((p) => (
                      <div
                        key={p.id}
                        className="flex items-center justify-between rounded-lg border p-3"
                      >
                        <div>
                          <p className="text-sm font-medium">{p.type}</p>
                          <p className="text-xs text-muted-foreground">
                            {new Date(p.createdAt).toLocaleDateString('vi-VN')} — {p.provider}
                          </p>
                        </div>
                        <div className="text-right">
                          <p className="font-semibold">{formatVND(p.amountVND)}</p>
                          <Badge
                            variant={
                              p.status === 'COMPLETED'
                                ? 'default'
                                : p.status === 'FAILED'
                                  ? 'destructive'
                                  : 'secondary'
                            }
                          >
                            {p.status === 'COMPLETED'
                              ? 'Thành công'
                              : p.status === 'FAILED'
                                ? 'Thất bại'
                                : p.status === 'PENDING'
                                  ? 'Chờ xử lý'
                                  : p.status}
                          </Badge>
                        </div>
                      </div>
                    ))}
                  </div>
                )}
              </CardContent>
            </Card>
          </TabsContent>
        </Tabs>
      )}

      {/* Upgrade dialog */}
      <Dialog open={!!upgradeTarget} onOpenChange={(o) => !o && setUpgradeTarget(null)}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>
              Nâng cấp lên {PLAN_TIER_LABELS[upgradeTarget?.tier ?? ''] ?? upgradeTarget?.name}
            </DialogTitle>
            <DialogDescription>
              Xác nhận nâng cấp gói dịch vụ. Bạn sẽ được chuyển hướng đến trang thanh toán.
            </DialogDescription>
          </DialogHeader>
          <div className="space-y-2 rounded-lg border bg-muted/50 p-4 text-sm">
            <div className="flex justify-between">
              <span className="text-muted-foreground">Gói</span>
              <span className="font-medium">
                {PLAN_TIER_LABELS[upgradeTarget?.tier ?? ''] ?? upgradeTarget?.name}
              </span>
            </div>
            <div className="flex justify-between">
              <span className="text-muted-foreground">Chu kỳ</span>
              <span className="font-medium">
                {billingCycle === 'monthly' ? 'Hàng tháng' : 'Hàng năm'}
              </span>
            </div>
            <div className="flex justify-between">
              <span className="text-muted-foreground">Giá</span>
              <span className="font-semibold text-primary">
                {upgradeTarget &&
                  formatVND(
                    billingCycle === 'monthly'
                      ? upgradeTarget.priceMonthlyVND
                      : upgradeTarget.priceYearlyVND,
                  )}
              </span>
            </div>
          </div>
          <DialogFooter>
            <Button variant="outline" onClick={() => setUpgradeTarget(null)}>
              Hủy
            </Button>
            <Button onClick={handleUpgrade} disabled={processing}>
              {processing ? 'Đang xử lý...' : 'Xác nhận nâng cấp'}
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}