import Link from "next/link";
import { redirect } from "next/navigation";
import { getTranslations } from "next-intl/server";
import {
  Compass,
  LayoutDashboard,
  Boxes,
  GitBranch,
  ShieldAlert,
  ClipboardCheck,
  ShieldCheck,
  KanbanSquare,
  ListChecks,
  Siren,
  BookOpenText,
  MessagesSquare,
  Network,
  FolderCheck,
  Truck,
  LineChart,
  Search,
  Settings,
} from "lucide-react";
import { auth, signOut } from "@/server/auth";
import { dbForTenant, prisma } from "@/server/db";
import { hasPermission } from "@/server/rbac";
import { isTokenStillValid } from "@/server/sessions";
import { resolveMfaRequired } from "@/lib/mfa-policy";
import { HREF_TO_MODULE } from "@/lib/modules";
import { AUDIT_READINESS_MODULE_KEY } from "@/lib/audit-readiness/activation";
import { resolveTenantBranding } from "@/lib/brand";
import { Button } from "@/components/ui/button";
import { NavLink } from "@/components/nav-link";
import { TenantBrand } from "@/components/brand/tenant-brand";
import { TenantSwitcher } from "@/components/tenant-switcher";
import { UiLocaleSwitcher } from "@/components/ui-locale-switcher";
import { CertviaLogo } from "@/components/brand/certvia-logo";

export default async function AppLayout({
  children,
}: Readonly<{ children: React.ReactNode }>) {
  const session = await auth();
  if (!session?.user) redirect("/login");
  // WS2: angemeldet, aber (noch) kein aktiver Mandant (mehrere Mitgliedschaften ohne
  // Slug) → Auswahlseite. MUSS vor jeder dbForTenant-Nutzung stehen (leerer tenantId).
  if (!session.user.tenantId) redirect("/select-tenant");

  // Kontostatus (autoritativ aus DB, nicht aus dem JWT): deaktivierte Nutzer werden
  // abgemeldet, ein offener Passwortwechsel wird erzwungen (Force-Change).
  // Option C (WS4): Membership-Status kommt vom User, die globalen Auth-Zustände
  // (Passwortzwang, Kill-Switch, MFA, globaler Sperrstatus) von der Identity.
  const account = await dbForTenant(session.user.tenantId).user.findUnique({
    where: { id: session.user.id },
    select: { status: true },
  });
  const identity = session.user.identityId
    ? await prisma.identity.findUnique({
        where: { id: session.user.identityId },
        select: { status: true, mustChangePassword: true, sessionsValidAfter: true, mfaEnrolledAt: true, uiLocale: true },
      })
    : null;
  // SEC2: serverseitig entwertete Sessions (Passwort-Reset/-Wechsel) sofort abmelden.
  if (identity && !isTokenStillValid(session.user.tokenIssuedAt, identity.sessionsValidAfter)) {
    await signOut({ redirectTo: "/login" });
  }
  if (!account || account.status !== "ACTIVE" || !identity || identity.status !== "ACTIVE") {
    return (
      <main className="flex min-h-screen flex-1 items-center justify-center p-6">
        <div className="shadow-card w-full max-w-sm rounded-2xl border bg-card p-8 text-center">
          <CertviaLogo variant="lockup" theme="dark" height={34} className="mx-auto" />
          <p className="mt-5 font-heading text-lg font-semibold">Konto deaktiviert</p>
          <p className="mt-1 text-sm text-muted-foreground">Ihr Zugang wurde deaktiviert. Bitte wenden Sie sich an Ihre Administration.</p>
          <form action={async () => { "use server"; await signOut({ redirectTo: "/login" }); }} className="mt-5">
            <Button type="submit" variant="outline" className="w-full">Abmelden</Button>
          </form>
        </div>
      </main>
    );
  }
  if (identity.mustChangePassword) redirect("/change-password");

  // SEC3-a/-b: MFA-Enrollment-Gate. Verlangt der Mandant MFA und hat die Identity weder TOTP
  // noch einen Passkey, wird die Einrichtung erzwungen (Pflichtseite außerhalb dieses Layouts).
  if (!identity.mfaEnrolledAt) {
    const settings = await dbForTenant(session.user.tenantId).tenantSettings.findFirst({ select: { securityPolicy: true } });
    if (resolveMfaRequired(settings?.securityPolicy)) {
      const passkeys = session.user.identityId
        ? await prisma.webAuthnCredential.count({ where: { identityId: session.user.identityId } })
        : 0;
      if (passkeys === 0) redirect("/enroll-mfa");
    }
  }

  const t = await getTranslations("nav");
  const tc = await getTranslations("common");

  const nav = [
    { href: "/dashboard", label: t("dashboard"), icon: LayoutDashboard, enabled: true },
    { href: "/onboarding", label: t("onboarding"), icon: Compass, enabled: true },
    // M4: nur sichtbar, wenn der Audit-Wizard scharfgeschaltet ist (Opt-in-Flag unten).
    { href: "/audit-readiness", label: t("auditReadiness"), icon: ShieldCheck, enabled: true, requiresAudit: true },
    { href: "/assets", label: t("assets"), icon: Boxes, enabled: true },
    { href: "/processes", label: t("bia"), icon: GitBranch, enabled: true },
    { href: "/risks", label: t("risks"), icon: ShieldAlert, enabled: true },
    { href: "/soa", label: t("soa"), icon: ClipboardCheck, enabled: true },
    { href: "/measures", label: t("measures"), icon: KanbanSquare, enabled: true },
    { href: "/tasks", label: t("tasks"), icon: ListChecks, enabled: true },
    { href: "/incidents", label: t("incidents"), icon: Siren, enabled: true },
    { href: "/policies", label: t("policies"), icon: BookOpenText, enabled: true },
    { href: "/chat", label: t("chat"), icon: MessagesSquare, enabled: false },
    { href: "/dependencies", label: t("dependencies"), icon: Network, enabled: true },
    { href: "/evidence", label: t("evidence"), icon: FolderCheck, enabled: false },
    { href: "/suppliers", label: t("suppliers"), icon: Truck, enabled: true },
    { href: "/review", label: t("review"), icon: LineChart, enabled: true },
  ];

  // Modul-Gating: deaktivierte Module werden ausgeblendet (§3.4)
  const [moduleRows, brandingSettings] = await Promise.all([
    dbForTenant(session.user.tenantId).tenantModule.findMany(),
    dbForTenant(session.user.tenantId).tenantSettings.findUnique({
      where: { tenantId: session.user.tenantId },
      select: { accent: true },
    }),
  ]);
  // Certvia ist der Default; ein Mandanten-Logo überschreibt später nur, wenn gesetzt (S8).
  const branding = resolveTenantBranding(brandingSettings);
  const disabledModules = new Set(moduleRows.filter((m) => !m.enabled).map((m) => m.moduleKey));
  const moduleEnabled = (href: string) => {
    const key = HREF_TO_MODULE[href];
    return !key || !disabledModules.has(key);
  };
  // M4: Audit-Wizard ist opt-in (Default aus) — nur bei ausdrücklicher Aktivierung sichtbar.
  const auditEnabled = moduleRows.some((m) => m.moduleKey === AUDIT_READINESS_MODULE_KEY && m.enabled);
  const visibleNav = nav.filter(
    (item) =>
      (!("requiresAudit" in item) || !item.requiresAudit || auditEnabled) &&
      (!item.enabled || moduleEnabled(item.href)),
  );

  const canManageTenant = hasPermission(session, "tenant:manage");

  const initials = (session.user.name ?? "?")
    .split(/\s+/)
    .map((p) => p[0])
    .slice(0, 2)
    .join("")
    .toUpperCase();

  async function logout() {
    "use server";
    await signOut({ redirectTo: "/login" });
  }

  return (
    <div className="flex min-h-screen">
      <aside className="flex w-60 shrink-0 flex-col border-r border-sidebar-border bg-sidebar">
        <div className="border-b border-sidebar-border px-4 pt-5 pb-3.5">
          <Link href="/dashboard" aria-label={branding.productName}>
            <TenantBrand branding={branding} height={36} />
          </Link>
          <TenantSwitcher memberships={session.user.memberships ?? []} activeSlug={session.user.tenantSlug} />
        </div>
        <nav className="flex-1 space-y-0.5 overflow-y-auto px-2.5 py-3">
          {visibleNav.map((item) =>
            item.enabled ? (
              <NavLink key={item.href} href={item.href}>
                <item.icon className="size-[18px] opacity-85" />
                {item.label}
              </NavLink>
            ) : (
              <span
                key={item.href}
                title={tc("comingSoon")}
                className="flex cursor-not-allowed items-center gap-2.5 rounded-lg px-3 py-2 text-[13.5px] font-semibold text-muted-foreground/50"
              >
                <item.icon className="size-[18px]" />
                {item.label}
              </span>
            )
          )}

          {canManageTenant && (
            <div className="mt-2 space-y-0.5 border-t border-sidebar-border pt-2">
              <NavLink href="/settings">
                <Settings className="size-[18px] opacity-85" /> {t("settings")}
              </NavLink>
            </div>
          )}
        </nav>
      </aside>

      <div className="flex min-w-0 flex-1 flex-col">
        <header className="sticky top-0 z-10 flex items-center gap-4 border-b bg-[var(--panel)] px-6 py-2.5 backdrop-blur-md">
          <form
            method="GET"
            action="/assets"
            className="flex w-full max-w-105 items-center gap-2 rounded-lg border bg-muted px-3 py-2 text-muted-foreground"
          >
            <Search className="size-4 shrink-0" />
            <input
              name="q"
              placeholder={tc("search")}
              className="w-full border-0 bg-transparent text-[13px] text-foreground outline-none placeholder:text-muted-foreground"
            />
          </form>
          <div className="flex-1" />
          <UiLocaleSwitcher current={identity.uiLocale} />
          <Link href="/account" className="flex items-center gap-3" title="Mein Konto (MFA)">
            <div className="text-right leading-tight">
              <p className="text-[13px] font-semibold">{session.user.name}</p>
              <p className="text-xs text-muted-foreground">{session.user.tenantSlug}</p>
            </div>
            <div className="bg-grad-soft grid size-9.5 shrink-0 place-items-center rounded-full font-heading text-sm font-bold text-white">
              {initials}
            </div>
          </Link>
          <form action={logout}>
            <Button type="submit" variant="ghost" size="sm">
              {tc("logout")}
            </Button>
          </form>
        </header>
        {children}
      </div>
    </div>
  );
}