import React from 'react';
import { Location, useLocation, useNavigate } from 'react-router-dom';
import { useTranslation } from 'react-i18next';
import { Sparkles, ShieldCheck, Images, ArrowRight, Loader2 } from 'lucide-react';

import { Alert, AlertDescription, AlertTitle } from '@/components/ui/alert';
import { Button } from '@/components/ui/button';
import AppearanceToggleDropdown from '@/components/appearance-dropdown';
import AppLogoIcon from '@/components/app-logo-icon';

import { useAuth } from '../auth/context';
import { ADMIN_HOME_PATH } from '../constants';

interface LocationState {
  from?: Location;
}

const featureIcons = [Sparkles, ShieldCheck, Images];

export default function LoginPage(): JSX.Element {
  const { status, login } = useAuth();
  const { t } = useTranslation('auth');
  const location = useLocation();
  const navigate = useNavigate();
  const searchParams = React.useMemo(() => new URLSearchParams(location.search), [location.search]);
  const oauthError = searchParams.get('error');

  React.useEffect(() => {
    if (status === 'authenticated') {
      navigate(ADMIN_HOME_PATH, { replace: true });
    }
  }, [status, navigate]);

  const redirectTarget = React.useMemo(() => {
    const state = location.state as LocationState | null;
    if (state?.from) {
      const from = state.from;
      const search = from.search ?? '';
      const hash = from.hash ?? '';
      return `${from.pathname}${search}${hash}`;
    }
    return ADMIN_HOME_PATH;
  }, [location.state]);

  const featureList = React.useMemo(() => {
    const raw = t('login.features', { returnObjects: true }) as unknown;
    if (!Array.isArray(raw)) {
      return [] as Array<{ text: string; Icon: typeof Sparkles }>;
    }
    return (raw as string[]).map((entry, index) => ({
      text: entry,
      Icon: featureIcons[index % featureIcons.length],
    }));
  }, [t]);

  const isLoading = status === 'loading';

  return (
    <div className="relative min-h-screen overflow-hidden bg-[var(--brand-navy)] text-white">
      <div className="pointer-events-none absolute inset-0 bg-[radial-gradient(circle_at_top,var(--brand-rose-soft)_0%,rgba(3,7,18,0.65)_55%,rgba(15,76,117,0.9)_100%)] opacity-95" />
      <div className="pointer-events-none absolute inset-y-0 right-[-25%] w-[55%] bg-[radial-gradient(circle_at_center,var(--brand-sky)_0%,rgba(255,255,255,0)_70%)] opacity-40" />
      <div className="pointer-events-none absolute inset-y-0 left-[-20%] w-[45%] bg-[radial-gradient(circle_at_center,var(--brand-rose)_0%,rgba(255,255,255,0)_65%)] opacity-35" />

      <div className="relative z-10 flex min-h-screen flex-col">
        <header className="mx-auto flex w-full max-w-6xl items-center justify-between px-6 pt-10">
          <div className="flex items-center gap-3">
            <span className="flex h-12 w-12 items-center justify-center rounded-full bg-white/15 shadow-lg shadow-black/10 backdrop-blur">
              <AppLogoIcon className="h-7 w-7 text-white" />
            </span>
            <div>
              <p className="text-xs uppercase tracking-[0.35em] text-white/70">{t('login.badge')}</p>
              <p className="text-lg font-semibold">Fotospiel</p>
            </div>
          </div>
          <AppearanceToggleDropdown />
        </header>

        <main className="mx-auto flex w-full max-w-6xl flex-1 flex-col px-6 pb-16 pt-12">
          <div className="grid flex-1 gap-12 lg:grid-cols-[0.95fr_1.05fr]" data-testid="tenant-login-layout">
            <section className="order-2 space-y-10 lg:order-1">
              <div className="space-y-5">
                <span className="inline-flex items-center gap-2 rounded-full border border-white/20 bg-white/10 px-4 py-1 text-sm font-medium text-white/80 backdrop-blur">
                  <Sparkles className="h-4 w-4 text-[var(--brand-gold)]" />
                  {t('login.badge')}
                </span>
                <h1 className="text-4xl font-semibold leading-tight sm:text-5xl">
                  {t('login.hero_title')}
                </h1>
                <p className="max-w-xl text-base text-white/80 sm:text-lg">
                  {t('login.hero_subtitle')}
                </p>
              </div>

              {featureList.length ? (
                <div className="grid gap-4 sm:grid-cols-2">
                  {featureList.map(({ text, Icon }, index) => (
                    <div
                      key={`login-feature-${index}`}
                      className="group relative overflow-hidden rounded-2xl border border-white/15 bg-white/10 p-5 shadow-lg shadow-black/5 backdrop-blur transition hover:border-white/35"
                    >
                      <Icon className="mb-3 h-5 w-5 text-[var(--brand-gold)] transition group-hover:text-white" />
                      <p className="text-sm text-white/90">{text}</p>
                    </div>
                  ))}
                </div>
              ) : null}

              <p className="flex items-center gap-2 text-sm text-white/70">
                <ArrowRight className="h-4 w-4" />
                {t('login.lead')}
              </p>
            </section>

            <section className="order-1 lg:order-2">
              <div className="relative">
                <div className="absolute inset-0 -translate-y-4 translate-x-6 scale-95 rounded-3xl bg-white/20 opacity-50 blur-2xl" />
                <div className="relative overflow-hidden rounded-3xl border border-white/20 bg-white/90 p-10 text-slate-900 shadow-2xl shadow-black/20 backdrop-blur-xl dark:border-white/10 dark:bg-slate-900/90 dark:text-slate-50">
                  <div className="space-y-6">
                    <div className="space-y-2">
                      <h2 className="text-2xl font-semibold">{t('login.title')}</h2>
                      <p className="text-sm text-slate-600 dark:text-slate-300">{t('login.panel_copy')}</p>
                    </div>

                    {oauthError ? (
                      <Alert className="border-red-400/40 bg-red-50/80 text-red-800 dark:border-red-500/40 dark:bg-red-500/10 dark:text-red-100">
                        <AlertTitle>{t('login.oauth_error_title')}</AlertTitle>
                        <AlertDescription>{t('login.oauth_error', { message: oauthError })}</AlertDescription>
                      </Alert>
                    ) : null}

                    <Button
                      size="lg"
                      className="group flex w-full items-center justify-center gap-2 rounded-full bg-gradient-to-r from-[var(--brand-rose)] via-[var(--brand-gold)] to-[var(--brand-sky)] px-8 py-3 text-base font-semibold text-slate-900 shadow-lg shadow-rose-400/30 transition hover:opacity-90 focus-visible:ring-4 focus-visible:ring-brand-rose/40 dark:text-slate-900"
                      disabled={isLoading}
                      onClick={() => login(redirectTarget)}
                    >
                      {isLoading ? (
                        <>
                          <Loader2 className="h-5 w-5 animate-spin" />
                          {t('login.loading')}
                        </>
                      ) : (
                        <>
                          {t('login.cta')}
                          <ArrowRight className="h-5 w-5 transition group-hover:translate-x-1" />
                        </>
                      )}
                    </Button>

                    <p className="text-xs leading-relaxed text-slate-500 dark:text-slate-300">
                      {t('login.support')}
                    </p>
                  </div>
                </div>
              </div>
            </section>
          </div>
        </main>
      </div>
    </div>
  );
}