"use client";

import {
  BeakerIcon,
  BellIcon,
  ChevronRightIcon,
  ClockIcon,
  EyeIcon,
  EyeSlashIcon,
  FireIcon,
  KeyIcon,
  MoonIcon,
  ScaleIcon,
  ShieldCheckIcon,
  SunIcon,
} from "@heroicons/react/24/outline";
import Link from "next/link";
import { useEffect, useMemo, useState } from "react";
import { DataPageLayout } from "@/app/_components/data-page-layout";
import { useTheme } from "@/app/_components/theme-provider";
import { authClient } from "@/lib/auth-client";
import { HellthGoals, loadHellthData } from "@/lib/hellth-data";
import { trpc } from "@/lib/trpc";
import { SectionCard } from "./_components/section-card";
import { SettingsTabs, useSettingsTab } from "./_components/settings-tabs";
import { StatusBanner } from "./_components/status-banner";

const PASSWORD_CHARS =
  "ABCDEFGHJKMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz23456789!@#$%&*";

const dietPreferenceOptions = [
  { id: "vegan", label: "Vegan" },
  { id: "vegetarian", label: "Vegetarisch" },
  { id: "meat", label: "Fleisch" },
  { id: "fish", label: "Fisch" },
] as const;

type DietPreference = (typeof dietPreferenceOptions)[number]["id"];

function todayKey() {
  return new Date().toISOString().slice(0, 10);
}

function generatePassword(length = 16) {
  const bytes = crypto.getRandomValues(new Uint8Array(length));
  return Array.from(bytes, (byte) => PASSWORD_CHARS[byte % PASSWORD_CHARS.length]!).join("");
}

async function toOptimizedAvatarDataUrl(file: File) {
  const bitmap = await createImageBitmap(file);
  const maxEdge = 320;
  const scale = Math.min(1, maxEdge / Math.max(bitmap.width, bitmap.height));
  const width = Math.max(1, Math.round(bitmap.width * scale));
  const height = Math.max(1, Math.round(bitmap.height * scale));

  const canvas = document.createElement("canvas");
  canvas.width = width;
  canvas.height = height;
  const ctx = canvas.getContext("2d");
  if (!ctx) throw new Error("Canvas nicht verfügbar");

  ctx.drawImage(bitmap, 0, 0, width, height);
  bitmap.close();

  const dataUrl = canvas.toDataURL("image/webp", 0.82);
  if (!dataUrl.startsWith("data:image/")) {
    throw new Error("Profilbild konnte nicht verarbeitet werden.");
  }
  if (dataUrl.length > 120_000) {
    throw new Error("Profilbild ist nach Komprimierung noch zu groß.");
  }
  return dataUrl;
}

const inputClass =
  "w-full rounded-lg border border-gray-200 bg-white px-3 py-2.5 text-sm text-gray-900 focus:border-[#0F766E] focus:outline-none focus:ring-2 focus:ring-[#0F766E]/20";
const labelClass = "mb-1.5 block text-sm font-medium text-gray-700";
const buttonPrimary =
  "inline-flex items-center justify-center rounded-lg bg-[#0F766E] px-4 py-2.5 text-sm font-semibold text-white shadow-sm transition-colors hover:bg-[#115E59] disabled:cursor-not-allowed disabled:opacity-50";
const buttonSecondary =
  "inline-flex items-center justify-center rounded-lg border border-gray-200 bg-white px-4 py-2.5 text-sm font-semibold text-gray-700 transition-colors hover:bg-gray-50 disabled:cursor-not-allowed disabled:opacity-50";

export default function EinstellungenPage() {
  const { isDark, toggleDark } = useTheme();
  const { active, setActive } = useSettingsTab();
  const utils = trpc.useUtils();
  const profileQuery = trpc.users.myProfile.useQuery();
  const securityQuery = trpc.security.status.useQuery();
  const healthOverviewQuery = trpc.health.overview.useQuery({ date: todayKey() });
  const passkeysQuery = authClient.useListPasskeys();
  const userKey = profileQuery.data?.id ?? profileQuery.data?.email ?? null;

  const [statusMessage, setStatusMessage] = useState<string | null>(null);
  const [errorMessage, setErrorMessage] = useState<string | null>(null);
  const [healthGoals, setHealthGoals] = useState<HellthGoals | null>(null);
  const [firstName, setFirstName] = useState("");
  const [lastName, setLastName] = useState("");
  const [phone, setPhone] = useState("");
  const [mobile, setMobile] = useState("");
  const [street, setStreet] = useState("");
  const [postalCode, setPostalCode] = useState("");
  const [city, setCity] = useState("");
  const [image, setImage] = useState<string | null>(null);
  const [dietPreferences, setDietPreferences] = useState<DietPreference[]>([
    "vegan",
    "vegetarian",
    "meat",
    "fish",
  ]);
  const [mealsPerDay, setMealsPerDay] = useState("3");
  const [cooksPerDay, setCooksPerDay] = useState("1");
  const [preferredMealPrepDays, setPreferredMealPrepDays] = useState("0");
  const [meatFishFrequency, setMeatFishFrequency] = useState<
    "none" | "once_per_day" | "flexible"
  >("flexible");

  const isPlatformAdmin = profileQuery.data?.role === "admin";

  const [currentPassword, setCurrentPassword] = useState("");
  const [newPassword, setNewPassword] = useState("");
  const [confirmNewPassword, setConfirmNewPassword] = useState("");
  const [showCurrentPassword, setShowCurrentPassword] = useState(false);
  const [showNewPassword, setShowNewPassword] = useState(false);
  const [showConfirmPassword, setShowConfirmPassword] = useState(false);
  const [newPasskeyName, setNewPasskeyName] = useState("");

  useEffect(() => {
    if (profileQuery.data) {
      setFirstName(profileQuery.data.firstName ?? profileQuery.data.name ?? "");
      setLastName(profileQuery.data.lastName ?? profileQuery.data.name ?? "");
      setPhone(profileQuery.data.phone ?? "");
      setMobile(profileQuery.data.mobile ?? "");
      setStreet(profileQuery.data.street ?? "");
      setPostalCode(profileQuery.data.postalCode ?? "");
      setCity(profileQuery.data.city ?? "");
      setImage(profileQuery.data.image ?? null);
    }
  }, [profileQuery.data]);

  useEffect(() => {
    if (!userKey) return;
    setHealthGoals(loadHellthData(userKey).goals);
  }, [userKey]);

  const updateMyProfile = trpc.users.updateMyProfile.useMutation({
    onSuccess: async () => {
      await Promise.all([
        utils.users.myProfile.invalidate(),
        utils.security.status.invalidate(),
      ]);
      setStatusMessage("Profil gespeichert.");
      setErrorMessage(null);
    },
    onError: (error) => {
      setErrorMessage(error.message);
      setStatusMessage(null);
    },
  });

  const changeMyPassword = trpc.users.changeMyPassword.useMutation({
    onSuccess: () => {
      setCurrentPassword("");
      setNewPassword("");
      setConfirmNewPassword("");
      setStatusMessage("Passwort erfolgreich aktualisiert.");
      setErrorMessage(null);
    },
    onError: (error) => {
      setErrorMessage(error.message);
      setStatusMessage(null);
    },
  });

  const updateHealthProfile = trpc.health.upsertProfile.useMutation({
    onSuccess: async () => {
      await healthOverviewQuery.refetch();
      await utils.health.recipeRecommendations.invalidate();
      setStatusMessage("Essenspräferenzen gespeichert.");
      setErrorMessage(null);
    },
    onError: (error) => {
      setErrorMessage(error.message);
      setStatusMessage(null);
    },
  });

  useEffect(() => {
    const profile = healthOverviewQuery.data?.profile;
    if (!profile) return;
    setDietPreferences(
      (profile.dietPreferences?.length
        ? profile.dietPreferences
        : ["vegan", "vegetarian", "meat", "fish"]) as DietPreference[],
    );
    setMealsPerDay(String(profile.mealsPerDay ?? 3));
    setCooksPerDay(String(profile.cooksPerDay ?? 1));
    setPreferredMealPrepDays(String(profile.preferredMealPrepDays ?? 0));
    setMeatFishFrequency(
      (profile.meatFishFrequency as "none" | "once_per_day" | "flexible") ?? "flexible",
    );
  }, [healthOverviewQuery.data?.profile]);

  function toggleDietPreference(preference: DietPreference) {
    setDietPreferences((current) => {
      const next = current.includes(preference)
        ? current.filter((item) => item !== preference)
        : [...current, preference];
      return next.length ? next : current;
    });
  }

  function saveEatingPreferences() {
    const profile = healthOverviewQuery.data?.profile;
    updateHealthProfile.mutate({
      goal: profile?.goal ?? "healthier",
      age: profile?.age ?? null,
      heightCm: profile?.heightCm == null ? null : Number(profile.heightCm),
      currentWeightKg:
        profile?.currentWeightKg == null ? null : Number(profile.currentWeightKg),
      targetWeightKg: profile?.targetWeightKg == null ? null : Number(profile.targetWeightKg),
      activityLevel: profile?.activityLevel ?? "moderate",
      dietStyle: profile?.dietStyle ?? "flexible",
      dietPreferences,
      mealsPerDay: Number(mealsPerDay) || 3,
      cooksPerDay: Number(cooksPerDay) || 1,
      preferredMealPrepDays: Number(preferredMealPrepDays) || 0,
      meatFishFrequency,
      cookingTime:
        (profile?.cookingTime as "low" | "medium" | "high" | undefined) ?? "medium",
      budgetFocus: profile?.budgetFocus ?? false,
      excludedFoods: profile?.excludedFoods ?? null,
      biggestChallenge: profile?.biggestChallenge ?? null,
      medicalNote: profile?.medicalNote ?? false,
      completed: Boolean(profile?.completedAt),
    });
  }

  const isBusy = updateMyProfile.isPending || changeMyPassword.isPending;
  const passwordMismatch =
    confirmNewPassword.length > 0 && newPassword !== confirmNewPassword;
  const canSaveProfile = useMemo(
    () =>
      !!firstName.trim() &&
      firstName.trim().length >= 2 &&
      (firstName.trim() !==
        (profileQuery.data?.firstName ?? profileQuery.data?.name ?? "") ||
        (lastName.trim() || null) !== (profileQuery.data?.lastName ?? null) ||
        (phone.trim() || null) !== (profileQuery.data?.phone ?? null) ||
        (mobile.trim() || null) !== (profileQuery.data?.mobile ?? null) ||
        (street.trim() || null) !== (profileQuery.data?.street ?? null) ||
        (postalCode.trim() || null) !== (profileQuery.data?.postalCode ?? null) ||
        (city.trim() || null) !== (profileQuery.data?.city ?? null) ||
        (image ?? null) !== (profileQuery.data?.image ?? null)),
    [
      firstName,
      lastName,
      phone,
      mobile,
      street,
      postalCode,
      city,
      image,
      profileQuery.data?.firstName,
      profileQuery.data?.name,
      profileQuery.data?.lastName,
      profileQuery.data?.phone,
      profileQuery.data?.mobile,
      profileQuery.data?.street,
      profileQuery.data?.postalCode,
      profileQuery.data?.city,
      profileQuery.data?.image,
    ],
  );

  async function handleAddPasskey() {
    setErrorMessage(null);
    setStatusMessage(null);
    const result = await authClient.passkey.addPasskey({
      name: newPasskeyName.trim() || undefined,
    });
    if (result.error) {
      setErrorMessage(result.error.message ?? "Passkey konnte nicht hinzugefuegt werden.");
      return;
    }
    setStatusMessage("Passkey erfolgreich hinzugefuegt.");
    setNewPasskeyName("");
    await passkeysQuery.refetch();
  }

  async function handleImageUpload(file: File) {
    if (!file.type.startsWith("image/")) {
      setErrorMessage("Bitte eine Bilddatei auswählen.");
      return;
    }
    if (file.size > 5 * 1024 * 1024) {
      setErrorMessage("Profilbild ist zu groß. Maximal 5 MB.");
      return;
    }
    try {
      const dataUrl = await toOptimizedAvatarDataUrl(file);
      setImage(dataUrl);
      setErrorMessage(null);
    } catch (error) {
      setErrorMessage(
        error instanceof Error
          ? error.message
          : "Profilbild konnte nicht verarbeitet werden.",
      );
    }
  }

  function handleSaveProfile() {
    setStatusMessage(null);
    setErrorMessage(null);
    updateMyProfile.mutate({
      firstName: firstName.trim(),
      lastName: lastName.trim() || null,
      phone: phone.trim() || null,
      mobile: mobile.trim() || null,
      street: street.trim() || null,
      postalCode: postalCode.trim() || null,
      city: city.trim() || null,
      image,
    });
  }

  function handleChangePassword() {
    setStatusMessage(null);
    setErrorMessage(null);
    changeMyPassword.mutate({ currentPassword, newPassword });
  }

  return (
    <DataPageLayout
      title="Einstellungen"
      description="Profil, Sicherheit und persönliche Vorlieben"
    >
      <div className="space-y-6">
        <SettingsTabs active={active} onChange={setActive} />

        <StatusBanner status={statusMessage} error={errorMessage} />

        {profileQuery.isLoading ? (
          <div className="rounded-xl border border-gray-200 bg-white px-4 py-3 text-sm text-gray-500">
            Profil wird geladen...
          </div>
        ) : null}

        {active === "profil" ? (
          <SectionCard
            title="Mein Profil"
            description="Persönliche Daten und Kontakt. E-Mail-Änderung erfolgt über das Konto."
            footer={
              <div className="flex justify-end">
                <button
                  type="button"
                  onClick={handleSaveProfile}
                  disabled={isBusy || !canSaveProfile}
                  className={buttonPrimary}
                >
                  Profil speichern
                </button>
              </div>
            }
          >
            <div className="flex flex-col gap-6 sm:flex-row sm:items-start">
              <div className="flex flex-col items-center gap-3 sm:items-start">
                <div className="h-24 w-24 overflow-hidden rounded-full border border-gray-200 bg-gray-100 shadow-inner">
                  {image ? (
                    // eslint-disable-next-line @next/next/no-img-element
                    <img src={image} alt="Profilbild" className="h-full w-full object-cover" />
                  ) : (
                    <div className="flex h-full w-full items-center justify-center text-2xl font-semibold text-gray-400">
                      {(firstName || profileQuery.data?.email || "?").slice(0, 1).toUpperCase()}
                    </div>
                  )}
                </div>
                <div className="flex flex-col gap-2 text-center sm:text-left">
                  <label className={`${buttonSecondary} cursor-pointer text-xs`}>
                    Bild hochladen
                    <input
                      type="file"
                      accept="image/*"
                      className="hidden"
                      onChange={(event) => {
                        const file = event.target.files?.[0];
                        if (file) void handleImageUpload(file);
                        event.currentTarget.value = "";
                      }}
                    />
                  </label>
                  {image ? (
                    <button
                      type="button"
                      onClick={() => setImage(null)}
                      className="text-xs font-medium text-red-600 hover:text-red-700"
                    >
                      Bild entfernen
                    </button>
                  ) : null}
                </div>
              </div>

              <div className="grid flex-1 grid-cols-1 gap-4 sm:grid-cols-2">
                <div>
                  <label className={labelClass}>Vorname</label>
                  <input
                    className={inputClass}
                    value={firstName}
                    onChange={(event) => setFirstName(event.target.value)}
                    placeholder="Vorname"
                  />
                </div>
                <div>
                  <label className={labelClass}>Nachname</label>
                  <input
                    className={inputClass}
                    value={lastName}
                    onChange={(event) => setLastName(event.target.value)}
                    placeholder="Nachname"
                  />
                </div>
                <div className="sm:col-span-2">
                  <label className={labelClass}>E-Mail</label>
                  <input
                    className={`${inputClass} cursor-not-allowed bg-gray-50 text-gray-500`}
                    value={profileQuery.data?.email ?? ""}
                    disabled
                  />
                </div>
                <div>
                  <label className={labelClass}>Telefon</label>
                  <input
                    className={inputClass}
                    value={phone}
                    onChange={(event) => setPhone(event.target.value)}
                    placeholder="Telefon"
                  />
                </div>
                <div>
                  <label className={labelClass}>Mobil</label>
                  <input
                    className={inputClass}
                    value={mobile}
                    onChange={(event) => setMobile(event.target.value)}
                    placeholder="Mobil"
                  />
                </div>
                <div className="sm:col-span-2">
                  <label className={labelClass}>Straße und Hausnummer</label>
                  <input
                    className={inputClass}
                    value={street}
                    onChange={(event) => setStreet(event.target.value)}
                    placeholder="Straße und Hausnummer"
                  />
                </div>
                <div>
                  <label className={labelClass}>PLZ</label>
                  <input
                    className={inputClass}
                    value={postalCode}
                    onChange={(event) => setPostalCode(event.target.value)}
                    placeholder="PLZ"
                  />
                </div>
                <div>
                  <label className={labelClass}>Ort</label>
                  <input
                    className={inputClass}
                    value={city}
                    onChange={(event) => setCity(event.target.value)}
                    placeholder="Ort"
                  />
                </div>
              </div>
            </div>
          </SectionCard>
        ) : null}

        {active === "ernaehrung" ? (
          <SectionCard
            title="Rezept- und Mahlzeiten-Präferenzen"
            description="Beeinflusst Vorschlaege und automatische Wochenplanung."
            footer={
              <div className="flex justify-end">
                <button
                  type="button"
                  onClick={saveEatingPreferences}
                  disabled={updateHealthProfile.isPending}
                  className={buttonPrimary}
                >
                  Präferenzen speichern
                </button>
              </div>
            }
          >
            <div>
              <p className={labelClass}>Ernährung</p>
              <div className="grid grid-cols-2 gap-2 sm:grid-cols-4">
                {dietPreferenceOptions.map((option) => {
                  const selected = dietPreferences.includes(option.id);
                  return (
                    <button
                      key={option.id}
                      type="button"
                      onClick={() => toggleDietPreference(option.id)}
                      className={`rounded-full px-3 py-2 text-sm font-semibold transition-colors ${
                        selected
                          ? "bg-[#0F766E] text-white shadow-sm"
                          : "bg-gray-100 text-gray-600 hover:bg-gray-200"
                      }`}
                    >
                      {option.label}
                    </button>
                  );
                })}
              </div>
            </div>
            <div className="grid grid-cols-1 gap-4 sm:grid-cols-3">
              <label className="block">
                <span className={labelClass}>Mahlzeiten/Tag</span>
                <input
                  className={inputClass}
                  inputMode="numeric"
                  value={mealsPerDay}
                  onChange={(event) => setMealsPerDay(event.target.value)}
                />
              </label>
              <label className="block">
                <span className={labelClass}>Kochvorgänge/Tag</span>
                <input
                  className={inputClass}
                  inputMode="numeric"
                  value={cooksPerDay}
                  onChange={(event) => setCooksPerDay(event.target.value)}
                />
              </label>
              <label className="block">
                <span className={labelClass}>Mealprep-Tage</span>
                <input
                  className={inputClass}
                  inputMode="numeric"
                  value={preferredMealPrepDays}
                  onChange={(event) => setPreferredMealPrepDays(event.target.value)}
                />
              </label>
            </div>
            <label className="block">
              <span className={labelClass}>Fleisch / Fisch</span>
              <select
                value={meatFishFrequency}
                onChange={(event) =>
                  setMeatFishFrequency(
                    event.target.value as "none" | "once_per_day" | "flexible",
                  )
                }
                className={inputClass}
              >
                <option value="none">nie</option>
                <option value="once_per_day">maximal 1x am Tag</option>
                <option value="flexible">flexibel</option>
              </select>
            </label>
          </SectionCard>
        ) : null}

        {active === "ziele" ? (
          <SectionCard
            title="Ziele"
            description="Kalorien, Makros, Wasser, Fasten und Gewicht werden unter /ziele detailliert eingestellt."
          >
            <div className="divide-y divide-gray-100">
              {[
                {
                  icon: FireIcon,
                  label: "Kalorien",
                  value: `${healthGoals?.calories ?? 2000} kcal`,
                  color: "text-orange-500",
                },
                {
                  icon: ScaleIcon,
                  label: "Makros (KH / Fett / Eiweiß)",
                  value: `${healthGoals?.carbs ?? 200} / ${healthGoals?.fat ?? 67} / ${
                    healthGoals?.protein ?? 150
                  } g`,
                  color: "text-blue-500",
                },
                {
                  icon: ClockIcon,
                  label: "Fasten",
                  value: `${healthGoals?.fastingHours ?? 12} h`,
                  color: "text-rose-500",
                },
                {
                  icon: BeakerIcon,
                  label: "Wasser",
                  value: `${healthGoals?.drinkMl ?? 2500} ml`,
                  color: "text-cyan-500",
                },
                {
                  icon: ScaleIcon,
                  label: "Gewicht",
                  value: `${healthGoals?.weightKg ?? 120} kg`,
                  color: "text-emerald-500",
                },
              ].map((item) => (
                <Link
                  key={item.label}
                  href="/ziele"
                  className="flex w-full items-center gap-4 py-4 text-left transition-colors hover:bg-gray-50"
                >
                  <item.icon className={`h-6 w-6 ${item.color}`} />
                  <span className="flex-1 text-sm font-semibold text-gray-900">
                    {item.label}
                  </span>
                  <span className="text-sm font-semibold text-gray-500">{item.value}</span>
                  <ChevronRightIcon className="h-4 w-4 text-gray-300" />
                </Link>
              ))}
            </div>
            {isPlatformAdmin ? (
              <div className="rounded-lg border border-gray-100 bg-gray-50 px-4 py-3 text-sm text-gray-600">
                Als Admin kannst du die{" "}
                <Link
                  href="/einstellungen/punkte"
                  className="font-semibold text-[#0F766E] underline"
                >
                  Punkte-Konfiguration
                </Link>{" "}
                global anpassen.
              </div>
            ) : null}
          </SectionCard>
        ) : null}

        {active === "sicherheit" ? (
          <div className="space-y-6">
            <SectionCard
              title="Zwei-Faktor-Authentifizierung"
              description="Schuetzt deinen Account zusaetzlich beim Login."
            >
              <div className="flex items-start gap-3 rounded-lg border border-gray-100 bg-gray-50 px-4 py-3">
                <ShieldCheckIcon
                  className={`h-5 w-5 shrink-0 ${
                    securityQuery.data?.twoFactorEnabled
                      ? "text-emerald-500"
                      : "text-gray-400"
                  }`}
                />
                <div className="flex-1">
                  <p className="text-sm font-semibold text-gray-900">
                    Status:{" "}
                    {securityQuery.data?.twoFactorEnabled ? "aktiv" : "nicht aktiv"}
                  </p>
                  {securityQuery.data?.twoFactorRecoveryRequired ? (
                    <p className="mt-1 text-xs text-amber-700">
                      Recovery aktiv: Bitte OTP neu einrichten.
                    </p>
                  ) : (
                    <p className="mt-1 text-xs text-gray-500">
                      Empfohlen, besonders für Admin-Accounts.
                    </p>
                  )}
                </div>
                <Link href="/sicherheit/2fa-setup" className={buttonSecondary}>
                  2FA verwalten
                </Link>
              </div>
            </SectionCard>

            <SectionCard
              title="Passkeys"
              description="Anmeldung per Geraet (Windows Hello, Touch ID, Passwortmanager)."
            >
              <div className="flex flex-col gap-2 sm:flex-row">
                <input
                  type="text"
                  value={newPasskeyName}
                  onChange={(event) => setNewPasskeyName(event.target.value)}
                  placeholder="Name (optional), z. B. Laptop"
                  className={inputClass}
                />
                <button
                  type="button"
                  onClick={() => void handleAddPasskey()}
                  disabled={isBusy}
                  className={buttonPrimary}
                >
                  <KeyIcon className="mr-1.5 h-4 w-4" />
                  Hinzufuegen
                </button>
              </div>
              <div className="space-y-2">
                {passkeysQuery.isPending ? (
                  <p className="text-xs text-gray-500">Passkeys werden geladen...</p>
                ) : null}
                {passkeysQuery.error ? (
                  <p className="text-xs text-red-600">
                    {passkeysQuery.error.message ?? "Passkeys konnten nicht geladen werden."}
                  </p>
                ) : null}
                {!passkeysQuery.isPending &&
                !passkeysQuery.error &&
                (passkeysQuery.data?.length ?? 0) === 0 ? (
                  <p className="text-xs text-gray-500">Noch keine Passkeys hinterlegt.</p>
                ) : null}
                {(passkeysQuery.data ?? []).map((item) => (
                  <div
                    key={item.id}
                    className="rounded-lg border border-gray-200 bg-gray-50 px-3 py-2 text-xs text-gray-700"
                  >
                    <p className="font-semibold text-gray-800">
                      {item.name || "Unbenannter Passkey"}
                    </p>
                    <p className="text-gray-500">
                      Erstellt: {new Date(item.createdAt).toLocaleString("de-DE")}
                    </p>
                  </div>
                ))}
              </div>
            </SectionCard>

            <SectionCard
              title="Passwort"
              description="Mindestens 16 Zeichen, gerne ein Generator."
              footer={
                <div className="flex flex-col gap-2 sm:flex-row sm:justify-between">
                  <button
                    type="button"
                    onClick={() => {
                      const generated = generatePassword(16);
                      setNewPassword(generated);
                      setConfirmNewPassword(generated);
                      setShowNewPassword(true);
                      setShowConfirmPassword(true);
                    }}
                    className={buttonSecondary}
                  >
                    Sicheres Passwort generieren
                  </button>
                  <button
                    type="button"
                    onClick={handleChangePassword}
                    disabled={
                      isBusy ||
                      !currentPassword ||
                      newPassword.length < 16 ||
                      confirmNewPassword.length < 16 ||
                      passwordMismatch
                    }
                    className={buttonPrimary}
                  >
                    Passwort aktualisieren
                  </button>
                </div>
              }
            >
              <PasswordInput
                value={currentPassword}
                onChange={setCurrentPassword}
                show={showCurrentPassword}
                onToggle={() => setShowCurrentPassword((value) => !value)}
                placeholder="Aktuelles Passwort"
              />
              <PasswordInput
                value={newPassword}
                onChange={setNewPassword}
                show={showNewPassword}
                onToggle={() => setShowNewPassword((value) => !value)}
                placeholder="Neues Passwort (mind. 16 Zeichen)"
              />
              <PasswordInput
                value={confirmNewPassword}
                onChange={setConfirmNewPassword}
                show={showConfirmPassword}
                onToggle={() => setShowConfirmPassword((value) => !value)}
                placeholder="Neues Passwort bestaetigen"
                invalid={passwordMismatch}
              />
              {passwordMismatch ? (
                <p className="text-xs text-red-600">
                  Die neuen Passwörter stimmen nicht überein.
                </p>
              ) : null}
            </SectionCard>
          </div>
        ) : null}

        {active === "anwendung" ? (
          <div className="space-y-6">
            <SectionCard
              title="Erscheinungsbild"
              description="Hell oder dunkel. Wird pro Browser gespeichert."
            >
              <div className="flex items-center justify-between rounded-lg border border-gray-100 bg-gray-50 px-4 py-3">
                <div className="flex items-center gap-3">
                  {isDark ? (
                    <MoonIcon className="h-5 w-5 text-indigo-400" />
                  ) : (
                    <SunIcon className="h-5 w-5 text-amber-500" />
                  )}
                  <div>
                    <p className="text-sm font-semibold text-gray-900">Dunkles Design</p>
                    <p className="text-xs text-gray-500">
                      {isDark ? "Dunkles Design ist aktiv" : "Helles Design ist aktiv"}
                    </p>
                  </div>
                </div>
                <button
                  type="button"
                  onClick={toggleDark}
                  className={`relative inline-flex h-6 w-11 shrink-0 cursor-pointer rounded-full transition-colors ${
                    isDark ? "bg-[#0F766E]" : "bg-gray-200"
                  }`}
                  role="switch"
                  aria-checked={isDark}
                  aria-label="Dunkles Design umschalten"
                >
                  <span
                    className={`pointer-events-none inline-block h-5 w-5 transform rounded-full bg-white shadow ring-0 transition ${
                      isDark ? "translate-x-5" : "translate-x-0.5"
                    } translate-y-0.5`}
                  />
                </button>
              </div>
            </SectionCard>

            <SectionCard
              title="Erinnerungen"
              description="Tracking-, Plan- und Wasser-Erinnerungen verwalten."
            >
              <Link
                href="/erinnerungen"
                className="flex items-center gap-3 rounded-lg border border-gray-100 bg-gray-50 px-4 py-3 transition-colors hover:bg-gray-100"
              >
                <BellIcon className="h-5 w-5 text-emerald-500" />
                <div className="flex-1">
                  <p className="text-sm font-semibold text-gray-900">
                    Taegliche Erinnerungen einrichten
                  </p>
                  <p className="text-xs text-gray-500">
                    Push, E-Mail und Browser-Notifications.
                  </p>
                </div>
                <ChevronRightIcon className="h-4 w-4 text-gray-300" />
              </Link>
            </SectionCard>
          </div>
        ) : null}
      </div>
    </DataPageLayout>
  );
}

function PasswordInput({
  value,
  onChange,
  show,
  onToggle,
  placeholder,
  invalid,
}: {
  value: string;
  onChange: (v: string) => void;
  show: boolean;
  onToggle: () => void;
  placeholder: string;
  invalid?: boolean;
}) {
  return (
    <div className="relative">
      <input
        type={show ? "text" : "password"}
        className={`${inputClass} pr-11 ${invalid ? "border-red-300" : ""}`}
        placeholder={placeholder}
        value={value}
        onChange={(event) => onChange(event.target.value)}
      />
      <button
        type="button"
        onClick={onToggle}
        className="absolute right-3 top-1/2 -translate-y-1/2 text-gray-400 hover:text-gray-600"
        aria-label={show ? "Passwort verbergen" : "Passwort anzeigen"}
      >
        {show ? <EyeSlashIcon className="h-4 w-4" /> : <EyeIcon className="h-4 w-4" />}
      </button>
    </div>
  );
}