"use client";

import { useEffect, useState, Suspense } from "react";
import { usePathname, useRouter } from "next/navigation";
import { useAuth } from "@/lib/auth/useAuth";
import { hasLiveSession } from "@/lib/api/mode";
import { isDemoPreviewSession } from "@/lib/auth/auth-client";
import { getPublicDemoMode } from "@/lib/env";
import { CleanSidebar } from "./CleanSidebar";
import { CleanHeader } from "./CleanHeader";

const isLiveFrontendMode = getPublicDemoMode() === "live";

// =============================================================================
// CleanAppLayout — full-bleed light workspace. One top-left menu opens the nav
// drawer at every breakpoint (no permanent rail, no bottom tab bar).
// =============================================================================

type CleanAppLayoutProps = {
  children: React.ReactNode;
};

function LoadingFallback() {
  return (
    <div className="flex flex-1 items-center justify-center bg-[#F7F6F2]">
      <div className="flex items-center gap-3">
        <span className="size-5 animate-spin rounded-full border-2 border-[#E5E7EB] border-t-[#111]" />
        <span className="text-[14px] text-[#9CA3AF]">Preparing your study space…</span>
      </div>
    </div>
  );
}

export function CleanAppLayout({ children }: CleanAppLayoutProps) {
  const router = useRouter();
  const pathname = usePathname();
  const { isLoading: isAuthLoading } = useAuth();
  const [navOpen, setNavOpen] = useState(false);

  const isLocalTuitionBetaRoute =
    pathname === "/tuition" || pathname?.startsWith("/tuition/");

  // ── Auth guard ──
  const unauthenticated =
    !isLocalTuitionBetaRoute &&
    isLiveFrontendMode &&
    !hasLiveSession() &&
    !isDemoPreviewSession();

  useEffect(() => {
    if (!isLocalTuitionBetaRoute && !isAuthLoading && unauthenticated) {
      const next = encodeURIComponent(pathname ?? "/home");
      router.replace(`/login?next=${next}`);
    }
  }, [isAuthLoading, isLocalTuitionBetaRoute, unauthenticated, pathname, router]);

  const blockChildren =
    !isLocalTuitionBetaRoute && (isAuthLoading || unauthenticated);

  // Close the drawer on route change.
  useEffect(() => {
    const t = window.setTimeout(() => setNavOpen(false), 0);
    return () => window.clearTimeout(t);
  }, [pathname]);

  // Escape closes; lock body scroll while the drawer is open.
  useEffect(() => {
    if (!navOpen) return;
    function onKeyDown(e: KeyboardEvent) {
      if (e.key === "Escape") setNavOpen(false);
    }
    window.addEventListener("keydown", onKeyDown);
    const prevOverflow = document.body.style.overflow;
    document.body.style.overflow = "hidden";
    return () => {
      window.removeEventListener("keydown", onKeyDown);
      document.body.style.overflow = prevOverflow;
    };
  }, [navOpen]);

  const closeNav = () => setNavOpen(false);

  return (
    <div className="relative flex h-screen min-h-screen flex-col overflow-hidden bg-[#F7F6F2] text-[#171717]">
      <CleanHeader onMenuClick={() => setNavOpen(true)} />

      {/* ── Nav drawer (all breakpoints) ── */}
      {navOpen && (
        <div className="fixed inset-0 z-50">
          <button
            type="button"
            aria-label="Close navigation"
            className="absolute inset-0 bg-black/40 backdrop-blur-sm animate-in fade-in duration-200"
            onClick={closeNav}
          />
          <div className="relative z-10 h-full w-[min(100%,300px)] max-w-[86vw] shadow-[8px_0_40px_rgba(0,0,0,0.25)] animate-in slide-in-from-left-full duration-300 ease-out">
            <CleanSidebar onNavigate={closeNav} onClose={closeNav} />
          </div>
        </div>
      )}

      {/* ── Main content ── */}
      <main className="relative min-h-0 flex-1 overflow-x-hidden overflow-y-auto bg-[#F7F6F2]">
        <Suspense fallback={<LoadingFallback />}>
          {blockChildren ? (
            <LoadingFallback />
          ) : (
            <div key={pathname} className="animate-in fade-in duration-200">
              {children}
            </div>
          )}
        </Suspense>
      </main>
    </div>
  );
}