import React, { useMemo, useState } from "react";
import { useTranslation } from 'react-i18next';
import type { TFunction } from 'i18next';
import { Check, Package as PackageIcon, Loader2 } from "lucide-react";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { useCheckoutWizard } from "../WizardContext";
import type { CheckoutPackage } from "../types";

const currencyFormatter = new Intl.NumberFormat("de-DE", {
  style: "currency",
  currency: "EUR",
  minimumFractionDigits: 2,
});

function translateFeature(feature: string, t: TFunction<'marketing'>) {
  const fallback = feature.replace(/_/g, ' ');
  return t(`packages.feature_${feature}`, { defaultValue: fallback });
}

function PackageSummary({ pkg, t }: { pkg: CheckoutPackage; t: TFunction<'marketing'> }) {
  const isFree = pkg.price === 0;

  return (
    <Card className={`shadow-sm ${isFree ? 'opacity-75' : ''}`}>
      <CardHeader className="space-y-1">
        <CardTitle className={`flex items-center gap-3 text-2xl ${isFree ? 'text-muted-foreground' : ''}`}>
          <PackageIcon className={`h-6 w-6 ${isFree ? 'text-muted-foreground' : 'text-primary'}`} />
          {pkg.name}
        </CardTitle>
        <CardDescription className="text-base text-muted-foreground">
          {pkg.description}
        </CardDescription>
      </CardHeader>
      <CardContent className="space-y-6">
        <div className="flex items-baseline gap-2">
          <span className={`text-3xl font-semibold ${isFree ? 'text-muted-foreground' : ''}`}>
            {pkg.price === 0 ? t('packages.free') : currencyFormatter.format(pkg.price)}
          </span>
          <Badge variant={isFree ? 'outline' : 'secondary'} className="uppercase tracking-wider text-xs">
            {pkg.type === 'reseller' ? t('packages.subscription') : t('packages.one_time')}
          </Badge>
        </div>
        {pkg.gallery_duration_label && (
          <div className="rounded-md border border-dashed border-muted px-3 py-2 text-sm text-muted-foreground">
            {t('packages.gallery_days_label')}: {pkg.gallery_duration_label}
          </div>
        )}
        {Array.isArray(pkg.description_breakdown) && pkg.description_breakdown.length > 0 && (
          <div className="space-y-3">
            <h4 className="text-sm font-semibold uppercase tracking-wide text-muted-foreground">
              {t('packages.breakdown_label')}
            </h4>
            <div className="grid gap-3 md:grid-cols-2">
              {pkg.description_breakdown.map((row, index) => (
                <div key={index} className="rounded-lg border border-muted/40 bg-muted/20 px-3 py-2">
                  {row.title && (
                    <p className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">{row.title}</p>
                  )}
                  <p className="text-sm text-muted-foreground">{row.value}</p>
                </div>
              ))}
            </div>
          </div>
        )}
        {Array.isArray(pkg.features) && pkg.features.length > 0 && (
          <ul className="space-y-3">
            {pkg.features.map((feature, index) => (
              <li key={index} className="flex items-start gap-3 text-sm text-muted-foreground">
                <Check className={`mt-0.5 h-4 w-4 ${isFree ? 'text-muted-foreground' : 'text-primary'}`} />
                <span>{translateFeature(feature, t)}</span>
              </li>
            ))}
          </ul>
        )}
      </CardContent>
    </Card>
  );
}

function PackageOption({ pkg, isActive, onSelect, t }: { pkg: CheckoutPackage; isActive: boolean; onSelect: () => void; t: TFunction<'marketing'> }) {
  const isFree = pkg.price === 0;

  return (
    <button
      type="button"
      onClick={onSelect}
      className={`w-full rounded-md border bg-background p-4 text-left transition focus:outline-none focus-visible:ring-2 focus-visible:ring-primary/40 ${
        isActive
          ? "border-primary shadow-sm"
          : isFree
            ? "border-border hover:border-primary/40 opacity-75 hover:opacity-100"
            : "border-border hover:border-primary/40"
      }`}
    >
      <div className="flex items-center justify-between text-sm font-medium">
        <span className={isFree ? "text-muted-foreground" : ""}>{pkg.name}</span>
        <span className={isFree ? "text-muted-foreground font-normal" : "text-muted-foreground"}>
          {pkg.price === 0 ? t('packages.free') : currencyFormatter.format(pkg.price)}
        </span>
      </div>
      <p className="mt-1 line-clamp-2 text-xs text-muted-foreground">{pkg.description}</p>
    </button>
  );
}

export const PackageStep: React.FC = () => {
  const { t } = useTranslation('marketing');
  const { selectedPackage, packageOptions, setSelectedPackage, resetPaymentState, nextStep } = useCheckoutWizard();
  const [isLoading, setIsLoading] = useState(false);


  // Early return if no package is selected
  if (!selectedPackage) {
    return (
      <div className="text-center py-8">
        <p className="text-muted-foreground">{t('checkout.package_step.no_package_selected')}</p>
      </div>
    );
  }

  const comparablePackages = useMemo(() => {
    // Filter by type and sort: free packages first, then by price ascending
    return packageOptions
      .filter((pkg: CheckoutPackage) => pkg.type === selectedPackage.type)
      .sort((a: CheckoutPackage, b: CheckoutPackage) => {
        // Free packages first
        if (a.price === 0 && b.price > 0) return -1;
        if (a.price > 0 && b.price === 0) return 1;
        // Then sort by price ascending
        return a.price - b.price;
      });
  }, [packageOptions, selectedPackage]);

  const handlePackageChange = (pkg: CheckoutPackage) => {
    if (pkg.id === selectedPackage.id) {
      return;
    }
    setSelectedPackage(pkg);
    resetPaymentState();
  };

  const handleNextStep = async () => {
    setIsLoading(true);
    // Kleine Verzögerung für bessere UX
    setTimeout(() => {
      nextStep();
      setIsLoading(false);
    }, 300);
  };

  return (
    <div className="grid gap-8 lg:grid-cols-[2fr_1fr]">
      <div className="space-y-6">
        <PackageSummary pkg={selectedPackage} t={t} />
        <div className="flex justify-end">
          <Button size="lg" onClick={handleNextStep} disabled={isLoading}>
            {isLoading ? (
              <>
                <Loader2 className="mr-2 h-4 w-4 animate-spin" />
                {t('checkout.package_step.loading')}
              </>
            ) : (
              t('checkout.package_step.next_to_account')
            )}
          </Button>
        </div>
      </div>
      <aside className="space-y-4">
        <h3 className="text-sm font-semibold uppercase tracking-wider text-muted-foreground">
          {t('checkout.package_step.alternatives_title')}
        </h3>
        <div className="space-y-3">
          {comparablePackages.map((pkg) => (
            <PackageOption
              key={pkg.id}
              pkg={pkg}
              isActive={pkg.id === selectedPackage.id}
              onSelect={() => handlePackageChange(pkg)}
              t={t}
            />
          ))}
          {comparablePackages.length === 0 && (
            <p className="text-xs text-muted-foreground">
              {t('checkout.package_step.no_alternatives')}
            </p>
          )}
        </div>
      </aside>
    </div>
  );
};