import React from 'react';
import { AlertTriangle, Loader2, Lock, LogOut, Mail, Moon, ShieldCheck, SunMedium, UserCog } from 'lucide-react';
import { useNavigate } from 'react-router-dom';

import AppearanceToggleDropdown from '@/components/appearance-dropdown';
import { Button } from '@/components/ui/button';
import { Switch } from '@/components/ui/switch';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { Card, CardContent } from '@/components/ui/card';
import { Badge } from '@/components/ui/badge';

import { AdminLayout } from '../components/AdminLayout';
import {
  TenantHeroCard,
  FrostedSurface,
  tenantHeroPrimaryButtonClass,
  tenantHeroSecondaryButtonClass,
  SectionCard,
  SectionHeader,
} from '../components/tenant';
import { useAuth } from '../auth/context';
import { ADMIN_EVENTS_PATH, ADMIN_LOGIN_PATH, ADMIN_PROFILE_PATH } from '../constants';
import { encodeReturnTo } from '../lib/returnTo';
import {
  getNotificationPreferences,
  updateNotificationPreferences,
  NotificationPreferences,
} from '../api';
import { getApiErrorMessage } from '../lib/apiError';
import { useTranslation } from 'react-i18next';

export default function SettingsPage() {
  const navigate = useNavigate();
  const { user, logout } = useAuth();
  const { t } = useTranslation('management');

  const [preferences, setPreferences] = React.useState<NotificationPreferences | null>(null);
  const [defaults, setDefaults] = React.useState<NotificationPreferences>({});
  const [loadingNotifications, setLoadingNotifications] = React.useState(true);
  const [savingNotifications, setSavingNotifications] = React.useState(false);
  const [notificationError, setNotificationError] = React.useState<string | null>(null);

  const heroDescription = t('settings.hero.description', { defaultValue: 'Gestalte das Erlebnis für dein Admin-Team – Darstellung, Benachrichtigungen und Session-Sicherheit.' });
  const heroSupporting = [
    t('settings.hero.summary.appearance', { defaultValue: 'Synchronisiere den Look & Feel mit dem Gästeportal oder schalte den Dark Mode frei.' }),
    t('settings.hero.summary.notifications', { defaultValue: 'Stimme Benachrichtigungen auf Aufgaben, Pakete und Live-Events ab.' })
  ];
  const accountName = user?.name ?? user?.email ?? 'Customer Admin';
  const heroPrimaryAction = (
    <Button
      size="sm"
      className={tenantHeroPrimaryButtonClass}
      onClick={() => navigate(ADMIN_PROFILE_PATH)}
    >
      {t('settings.hero.actions.profile', 'Profil bearbeiten')}
    </Button>
  );
  const heroSecondaryAction = (
    <Button
      size="sm"
      className={tenantHeroSecondaryButtonClass}
      onClick={() => navigate(ADMIN_EVENTS_PATH)}
    >
      {t('settings.hero.actions.events', 'Zur Event-Übersicht')}
    </Button>
  );
  const heroAside = (
    <FrostedSurface className="space-y-3 border-slate-200 p-5 text-slate-900 shadow-lg shadow-rose-300/20 dark:border-white/20 dark:bg-white/10">
      <div>
        <p className="text-xs uppercase tracking-[0.3em] text-slate-500 dark:text-slate-400">{t('settings.hero.accountLabel', { defaultValue: 'Angemeldeter Account' })}</p>
        <p className="mt-2 text-lg font-semibold text-slate-900 dark:text-slate-100">{accountName}</p>
        {user?.tenant_id ? (
          <p className="text-xs text-slate-600 dark:text-slate-400">Tenant #{user.tenant_id}</p>
        ) : null}
      </div>
      <p className="text-xs text-slate-600 dark:text-slate-400">{t('settings.hero.support', { defaultValue: 'Passe Einstellungen für dich und dein Team an – Änderungen wirken sofort im Admin.' })}</p>
    </FrostedSurface>
  );

  const translateNotification = React.useCallback(
    (key: string, fallback?: string, options?: Record<string, unknown>) =>
      t(key, { defaultValue: fallback, ...(options ?? {}) }),
    [t],
  );

  function handleLogout() {
    const target = new URL(ADMIN_LOGIN_PATH, window.location.origin);
    target.searchParams.set('reset-auth', '1');
    target.searchParams.set('return_to', encodeReturnTo(ADMIN_EVENTS_PATH));
    logout({ redirect: `${target.pathname}${target.search}` });
  }

  React.useEffect(() => {
    (async () => {
      try {
        const result = await getNotificationPreferences();
        setPreferences(result.preferences);
        setDefaults(result.defaults);
      } catch (error) {
        setNotificationError(getApiErrorMessage(error, t('settings.notifications.errorLoad', 'Benachrichtigungseinstellungen konnten nicht geladen werden.')));
      } finally {
        setLoadingNotifications(false);
      }
    })();
  }, [t]);

  return (
    <AdminLayout
      title="Einstellungen"
      subtitle="Passe das Erscheinungsbild deines Dashboards an und verwalte deine Session."
    >
      <TenantHeroCard
        badge={t('settings.hero.badge', { defaultValue: 'Administration' })}
        title={t('settings.title', { defaultValue: 'Einstellungen' })}
        description={heroDescription}
        supporting={heroSupporting}
        primaryAction={heroPrimaryAction}
        secondaryAction={heroSecondaryAction}
        aside={heroAside}
      />

      <div className="mt-6 grid gap-6 lg:grid-cols-[minmax(0,1.2fr)_minmax(0,0.8fr)]">
        <div className="space-y-6">
          <SectionCard className="space-y-6">
            <SectionHeader
              eyebrow={t('settings.appearance.badge', 'Darstellung')}
              title={t('settings.appearance.title', 'Darstellung & Branding')}
              description={t('settings.appearance.description', 'Passe den Admin an eure Markenfarben oder synchronisiere das System-Theme.')}
            />
            <div className="grid gap-3 md:grid-cols-2">
              <FrostedSurface className="flex items-start gap-3 border border-white/20 bg-white/70 p-4 text-slate-900 shadow-sm">
                <SunMedium className="mt-0.5 h-5 w-5 text-amber-500" />
                <div>
                  <p className="text-sm font-semibold">{t('settings.appearance.lightTitle', 'Heller Modus')}</p>
                  <p className="text-xs text-slate-600">{t('settings.appearance.lightCopy', 'Perfekt für Büros und klare Kontraste.')}</p>
                </div>
              </FrostedSurface>
              <FrostedSurface className="flex items-start gap-3 border border-white/20 bg-slate-900/80 p-4 text-white shadow-sm">
                <Moon className="mt-0.5 h-5 w-5 text-indigo-200" />
                <div>
                  <p className="text-sm font-semibold">{t('settings.appearance.darkTitle', 'Dunkler Modus')}</p>
                  <p className="text-xs text-slate-200">{t('settings.appearance.darkCopy', 'Schonend für Nachtproduktionen oder OLED-Displays.')}</p>
                </div>
              </FrostedSurface>
            </div>
            <div className="rounded-2xl border border-slate-200 bg-white/90 p-4 shadow-sm dark:border-slate-700 dark:bg-slate-900/40">
              <div className="flex flex-col gap-2 sm:flex-row sm:items-center sm:justify-between">
                <div>
                  <p className="text-sm font-semibold text-slate-900 dark:text-white">{t('settings.appearance.themeLabel', 'Theme wählen')}</p>
                  <p className="text-xs text-slate-600 dark:text-slate-400">
                    {t('settings.appearance.themeHint', 'Nutze automatische Anpassung oder überschreibe das Theme manuell.')}
                  </p>
                </div>
                <AppearanceToggleDropdown />
              </div>
            </div>
          </SectionCard>

          <SectionCard className="space-y-6">
            <SectionHeader
              eyebrow={t('settings.session.badge', 'Account & Sicherheit')}
              title={t('settings.session.title', 'Angemeldeter Account')}
              description={t('settings.session.description', 'Verwalte deine Sitzung oder wechsel schnell zu deinem Profil.')}
            />
            <div className="rounded-2xl border border-slate-200 bg-white/90 p-4 shadow-inner dark:border-slate-700 dark:bg-slate-900/40">
              <p className="text-sm text-slate-700 dark:text-slate-200">
                {user ? (
                  <>
                    {t('settings.session.loggedInAs', 'Eingeloggt als')} <span className="font-semibold text-slate-900 dark:text-white">{user.name ?? user.email ?? 'Customer Admin'}</span>
                    {user.tenant_id ? <span className="text-xs text-slate-500 dark:text-slate-400"> • Tenant #{user.tenant_id}</span> : null}
                  </>
                ) : (
                  t('settings.session.unknown', 'Aktuell kein Benutzer geladen.')
                )}
              </p>
              <div className="mt-4 flex flex-wrap gap-2 text-xs text-slate-500 dark:text-slate-400">
                <Badge variant="outline" className="border-emerald-200 text-emerald-700">
                  <ShieldCheck className="mr-1 h-3 w-3" /> {t('settings.session.security', 'SSO & 2FA aktivierbar')}
                </Badge>
                <Badge variant="outline" className="border-slate-200 text-slate-600">
                  <Lock className="mr-1 h-3 w-3" /> {t('settings.session.session', 'Session 12h gültig')}
                </Badge>
              </div>
            </div>
            <Alert className="border-amber-200 bg-amber-50 text-amber-900">
              <AlertDescription className="flex items-center gap-2 text-xs">
                <AlertTriangle className="h-4 w-4" />
                {t('settings.session.hint', 'Bei Gerätewechsel solltest du dich kurz ab- und wieder anmelden, um Berechtigungen zu synchronisieren.')}
              </AlertDescription>
            </Alert>
            <div className="flex flex-wrap gap-3">
              <Button variant="destructive" onClick={handleLogout} className="flex items-center gap-2">
                <LogOut className="h-4 w-4" /> {t('settings.session.logout', 'Abmelden')}
              </Button>
              <Button variant="secondary" onClick={() => navigate(ADMIN_PROFILE_PATH)} className="flex items-center gap-2">
                <UserCog className="h-4 w-4" /> {t('settings.profile.actions.openProfile', 'Profil bearbeiten')}
              </Button>
              <Button variant="ghost" onClick={() => navigate(-1)}>
                {t('settings.session.cancel', 'Zurück')}
              </Button>
            </div>
          </SectionCard>

          <SectionCard className="space-y-6">
            <SectionHeader
              eyebrow={t('settings.notifications.badge', 'Benachrichtigungen')}
              title={t('settings.notifications.title', 'Benachrichtigungen')}
              description={t('settings.notifications.description', 'Lege fest, für welche Ereignisse wir dich per E-Mail informieren.')}
            />
            {notificationError ? (
              <Alert variant="destructive">
                <AlertDescription>{notificationError}</AlertDescription>
              </Alert>
            ) : null}

            {loadingNotifications ? (
              <NotificationSkeleton />
            ) : preferences ? (
              <NotificationPreferencesForm
                preferences={preferences}
                defaults={defaults}
                onChange={(next) => setPreferences(next)}
                onReset={() => setPreferences(defaults)}
                onSave={async () => {
                  if (!preferences) {
                    return;
                  }
                  try {
                    setSavingNotifications(true);
                    const updated = await updateNotificationPreferences(preferences);
                    setPreferences(updated.preferences);
                    if (updated.defaults && Object.keys(updated.defaults).length > 0) {
                      setDefaults(updated.defaults);
                    }
                    setNotificationError(null);
                  } catch (error) {
                    setNotificationError(
                      getApiErrorMessage(error, t('settings.notifications.errorSave', 'Speichern fehlgeschlagen. Bitte versuche es erneut.')),
                    );
                  } finally {
                    setSavingNotifications(false);
                  }
                }}
                saving={savingNotifications}
                translate={translateNotification}
              />
            ) : null}
          </SectionCard>
        </div>
        <div className="space-y-6">
          <SupportCard />
        </div>
      </div>
    </AdminLayout>
  );
}

function NotificationPreferencesForm({
  preferences,
  defaults,
  onChange,
  onReset,
  onSave,
  saving,
  translate,
}: {
  preferences: NotificationPreferences;
  defaults: NotificationPreferences;
  onChange: (next: NotificationPreferences) => void;
  onReset: () => void;
  onSave: () => Promise<void>;
  saving: boolean;
  translate: (key: string, fallback?: string, options?: Record<string, unknown>) => string;
}) {
  const items = React.useMemo(() => buildPreferenceMeta(translate), [translate]);

  return (
    <div className="relative space-y-4 pb-16">
      <div className="space-y-3">
        {items.map((item) => {
          const checked = preferences[item.key] ?? defaults[item.key] ?? true;

          return (
            <FrostedSurface key={item.key} className="flex items-start justify-between gap-4 border border-slate-200 p-4 text-slate-900 shadow-sm shadow-rose-200/20 dark:border-pink-500/20 dark:bg-white/10">
              <div className="space-y-1">
                <h3 className="text-sm font-semibold text-slate-900 dark:text-slate-100">{item.label}</h3>
                <p className="text-sm text-slate-600 dark:text-slate-400">{item.description}</p>
              </div>
              <Switch
                checked={checked}
                onCheckedChange={(value) => onChange({ ...preferences, [item.key]: Boolean(value) })}
              />
            </FrostedSurface>
          );
        })}
      </div>
      <div className="sticky bottom-4 z-[1] flex flex-wrap items-center gap-3 rounded-2xl border border-slate-200 bg-white/95 p-3 shadow-lg shadow-rose-200/40 backdrop-blur dark:border-slate-700 dark:bg-slate-900/80">
        <Button onClick={onSave} disabled={saving} className="flex items-center gap-2 bg-gradient-to-r from-[#ff5f87] via-[#ec4899] to-[#6366f1] text-white shadow-md shadow-rose-400/30">
          {saving ? <Loader2 className="h-4 w-4 animate-spin" /> : null}
          {saving ? translate('settings.notifications.actions.save', 'Speichern') : translate('settings.notifications.actions.save', 'Speichern')}
        </Button>
        <Button variant="ghost" onClick={onReset} disabled={saving}>
          {translate('settings.notifications.actions.reset', 'Auf Standard setzen')}
        </Button>
        <span className="text-xs text-slate-500 dark:text-slate-400">
          {translate('settings.notifications.hint', 'Du kannst Benachrichtigungen jederzeit wieder aktivieren.')}
        </span>
      </div>
    </div>
  );
}

function buildPreferenceMeta(
  translate: (key: string, fallback?: string, options?: Record<string, unknown>) => string
): Array<{ key: keyof NotificationPreferences; label: string; description: string }> {
  const map = [
    {
      key: 'photo_thresholds',
      label: translate('settings.notifications.items.photoThresholds.label', 'Warnung bei Foto-Schwellen'),
      description: translate('settings.notifications.items.photoThresholds.description', 'Sende Warnungen bei 80 % und 95 % Foto-Auslastung.'),
    },
    {
      key: 'photo_limits',
      label: translate('settings.notifications.items.photoLimits.label', 'Sperre bei Foto-Limit'),
      description: translate('settings.notifications.items.photoLimits.description', 'Informiere mich, sobald keine Foto-Uploads mehr möglich sind.'),
    },
    {
      key: 'guest_thresholds',
      label: translate('settings.notifications.items.guestThresholds.label', 'Warnung bei Gästekontingent'),
      description: translate('settings.notifications.items.guestThresholds.description', 'Warnung kurz bevor alle Gästelinks vergeben sind.'),
    },
    {
      key: 'guest_limits',
      label: translate('settings.notifications.items.guestLimits.label', 'Sperre bei Gästelimit'),
      description: translate('settings.notifications.items.guestLimits.description', 'Hinweis, wenn keine neuen Gästelinks mehr erzeugt werden können.'),
    },
    {
      key: 'gallery_warnings',
      label: translate('settings.notifications.items.galleryWarnings.label', 'Galerie läuft bald ab'),
      description: translate('settings.notifications.items.galleryWarnings.description', 'Erhalte 7 und 1 Tag vor Ablauf eine Erinnerung.'),
    },
    {
      key: 'gallery_expired',
      label: translate('settings.notifications.items.galleryExpired.label', 'Galerie ist abgelaufen'),
      description: translate('settings.notifications.items.galleryExpired.description', 'Informiere mich, sobald Gäste die Galerie nicht mehr sehen können.'),
    },
    {
      key: 'event_thresholds',
      label: translate('settings.notifications.items.eventThresholds.label', 'Warnung bei Event-Kontingent'),
      description: translate('settings.notifications.items.eventThresholds.description', 'Hinweis, wenn das Reseller-Paket fast ausgeschöpft ist.'),
    },
    {
      key: 'event_limits',
      label: translate('settings.notifications.items.eventLimits.label', 'Sperre bei Event-Kontingent'),
      description: translate('settings.notifications.items.eventLimits.description', 'Nachricht, sobald keine weiteren Events erstellt werden können.'),
    },
    {
      key: 'package_expiring',
      label: translate('settings.notifications.items.packageExpiring.label', 'Paket läuft bald ab'),
      description: translate('settings.notifications.items.packageExpiring.description', 'Erinnerungen bei 30, 7 und 1 Tag vor Paketablauf.'),
    },
    {
      key: 'package_expired',
      label: translate('settings.notifications.items.packageExpired.label', 'Paket ist abgelaufen'),
      description: translate('settings.notifications.items.packageExpired.description', 'Benachrichtige mich, wenn das Paket abgelaufen ist.'),
    },
  ];

  return map as Array<{ key: keyof NotificationPreferences; label: string; description: string }>;
}

function NotificationSkeleton() {
  return (
    <div className="space-y-3">
      {Array.from({ length: 5 }).map((_, index) => (
        <FrostedSurface
          key={`notification-skeleton-${index}`}
          className="h-14 animate-pulse border border-white/20 bg-gradient-to-r from-white/30 via-white/60 to-white/30 shadow-inner dark:border-slate-800/60 dark:from-slate-800 dark:via-slate-700 dark:to-slate-800"
        />
      ))}
    </div>
  );
}

function SupportCard() {
  const { t } = useTranslation('management');
  return (
    <Card className="border border-slate-200 bg-white/90 shadow-sm dark:border-slate-800 dark:bg-slate-900/60">
      <CardContent className="space-y-4 p-5">
        <div>
          <p className="text-xs uppercase tracking-[0.3em] text-slate-500">{t('settings.support.badge', 'Hilfe & Support')}</p>
          <p className="mt-1 text-base font-semibold text-slate-900 dark:text-white">{t('settings.support.title', 'Team informieren')}</p>
          <p className="text-sm text-slate-600 dark:text-slate-300">{t('settings.support.copy', 'Benötigst du sofortige Hilfe? Unser Support reagiert in der Regel innerhalb weniger Stunden.')}</p>
        </div>
        <Button
          variant="secondary"
          className="w-full"
          onClick={() => {
            window.location.href = 'mailto:support@fotospiel.app';
          }}
        >
          <Mail className="mr-2 h-4 w-4" /> {t('settings.support.cta', 'Support kontaktieren')}
        </Button>
      </CardContent>
    </Card>
  );
}