"use client";

import { useEffect, useState, useSyncExternalStore } from "react";
import { useRouter } from "next/navigation";
import { Command } from "cmdk";
import { Dialog as DialogPrimitive } from "@base-ui/react/dialog";
import { Search } from "lucide-react";
import { adminLinks } from "@/components/admin/admin-nav";

interface SearchResults {
  users: { id: string; name: string; email: string; role: string }[];
  courses: { id: string; title: string; slug: string; published: boolean }[];
  lessons: {
    id: string;
    title: string;
    published: boolean;
    moduleId: string;
    courseId: string;
    courseTitle: string;
  }[];
}

const EMPTY: SearchResults = { users: [], courses: [], lessons: [] };
const MIN_QUERY = 2;
const DEBOUNCE_MS = 200;

const ROLE_LABEL: Record<string, string> = {
  student: "студент",
  curator: "куратор",
  admin: "админ",
};

const noopSubscribe = () => () => {};

function useShortcutLabel() {
  return useSyncExternalStore(
    noopSubscribe,
    () => (/Mac|iPhone|iPad/.test(navigator.platform) ? "⌘K" : "Ctrl K"),
    () => "Ctrl K",
  );
}

// DS-2: hard-edged group headings, accent highlight for the active row.
const groupClass =
  "mb-1 [&_[cmdk-group-heading]]:px-2 [&_[cmdk-group-heading]]:pt-3 [&_[cmdk-group-heading]]:pb-1 " +
  "[&_[cmdk-group-heading]]:text-xs [&_[cmdk-group-heading]]:font-bold [&_[cmdk-group-heading]]:uppercase " +
  "[&_[cmdk-group-heading]]:tracking-widest [&_[cmdk-group-heading]]:text-[var(--muted-foreground)]";
const itemClass =
  "flex min-h-[44px] cursor-pointer items-center gap-3 border-2 border-transparent px-2 py-1.5 text-sm " +
  "data-[selected=true]:border-[var(--foreground)] data-[selected=true]:bg-[var(--accent)]";

export function AdminCommandMenu({ onOpen }: { onOpen?: () => void }) {
  const router = useRouter();
  const shortcut = useShortcutLabel();
  const [open, setOpen] = useState(false);
  const [query, setQuery] = useState("");
  const [results, setResults] = useState<SearchResults>(EMPTY);
  const [loading, setLoading] = useState(false);

  // Global hotkey: Ctrl+K / ⌘K toggles the menu from anywhere in the admin.
  useEffect(() => {
    const onKeyDown = (e: KeyboardEvent) => {
      if ((e.metaKey || e.ctrlKey) && e.key.toLowerCase() === "k") {
        e.preventDefault();
        setOpen((v) => !v);
      }
    };
    window.addEventListener("keydown", onKeyDown);
    return () => window.removeEventListener("keydown", onKeyDown);
  }, []);

  // Debounced server lookup; stale responses are aborted.
  const trimmed = query.trim();
  useEffect(() => {
    if (trimmed.length < MIN_QUERY) return;
    const controller = new AbortController();
    const timer = setTimeout(() => {
      setLoading(true);
      fetch(`/api/admin/search?q=${encodeURIComponent(trimmed)}`, { signal: controller.signal })
        .then((r) => (r.ok ? r.json() : Promise.reject(new Error(`status ${r.status}`))))
        .then((data: SearchResults) => setResults(data))
        .catch((e: unknown) => {
          if ((e as Error).name !== "AbortError") {
            console.error("admin search failed", e);
            setResults(EMPTY);
          }
        })
        .finally(() => {
          if (!controller.signal.aborted) setLoading(false);
        });
    }, DEBOUNCE_MS);
    return () => {
      clearTimeout(timer);
      controller.abort();
    };
  }, [trimmed]);

  const active = trimmed.length >= MIN_QUERY;
  const shown = active ? results : EMPTY;
  const showLoading = active && loading;
  const needle = trimmed.toLowerCase();
  const sections = needle
    ? adminLinks.filter((l) => l.label.toLowerCase().includes(needle))
    : adminLinks;

  function go(href: string) {
    setOpen(false);
    setQuery("");
    setResults(EMPTY);
    router.push(href);
  }

  return (
    <>
      <button
        type="button"
        onClick={() => {
          onOpen?.();
          setOpen(true);
        }}
        className="flex w-full items-center gap-2 px-3 py-2 text-xs transition-colors hover:bg-[var(--sidebar-surface)] hover:text-[#F5F5F0]"
        style={{ border: "2px solid var(--sidebar-border)", color: "var(--sidebar-text)" }}
        aria-label="Поиск по админке"
      >
        <Search size={14} aria-hidden />
        <span className="flex-1 text-left">Поиск</span>
        <kbd className="text-[0.65rem] tracking-widest" style={{ fontFamily: "inherit" }}>
          {shortcut}
        </kbd>
      </button>

      <DialogPrimitive.Root
        open={open}
        onOpenChange={(next) => {
          setOpen(next);
          if (!next) setQuery("");
        }}
      >
        <DialogPrimitive.Portal>
          <DialogPrimitive.Backdrop
            className="fixed inset-0 z-50"
            style={{ background: "rgba(50,50,50,0.45)" }}
          />
          <DialogPrimitive.Popup
            className="fixed top-[12vh] left-1/2 z-50 w-[calc(100%-2rem)] max-w-xl -translate-x-1/2 outline-none"
            style={{
              background: "var(--background)",
              color: "var(--foreground)",
              border: "2px solid var(--foreground)",
              boxShadow: "6px 6px 0 0 var(--foreground)",
            }}
          >
            <DialogPrimitive.Title className="sr-only">Поиск по админке</DialogPrimitive.Title>
            <Command
              shouldFilter={false}
              label="Поиск по админке"
              loop
              // The input is the only tabbable element here, and Base UI's focus
              // guards let Tab leak out of a single-element trap (seen live:
              // focus walked to the sidebar while the menu stayed open). In a
              // command menu arrows move the selection, so Tab simply stays put.
              onKeyDown={(e) => {
                if (e.key === "Tab") e.preventDefault();
              }}
            >
              <div
                className="flex items-center gap-2 px-3"
                style={{ borderBottom: "2px solid var(--border)" }}
              >
                <Search size={16} aria-hidden style={{ color: "var(--muted-foreground)" }} />
                <Command.Input
                  value={query}
                  onValueChange={setQuery}
                  placeholder="Студент, курс, урок или раздел…"
                  className="h-12 flex-1 bg-transparent text-sm outline-none placeholder:text-[var(--muted-foreground)]"
                />
                {showLoading && (
                  <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
                    ищем…
                  </span>
                )}
              </div>

              <Command.List className="max-h-[60vh] overflow-y-auto p-2">
                <Command.Empty className="px-2 py-6 text-center text-sm" style={{ color: "var(--muted-foreground)" }}>
                  {!active ? "Введите хотя бы два символа" : showLoading ? "Ищем…" : "Ничего не нашлось"}
                </Command.Empty>

                {shown.users.length > 0 && (
                  <Command.Group heading="Студенты и сотрудники" className={groupClass}>
                    {shown.users.map((u) => (
                      <Command.Item
                        key={u.id}
                        value={`user:${u.id}`}
                        onSelect={() => go(`/admin/users/${u.id}`)}
                        className={itemClass}
                      >
                        <span className="min-w-0 flex-1">
                          <span className="block truncate font-medium">{u.name}</span>
                          <span className="block truncate text-xs" style={{ color: "var(--muted-foreground)" }}>
                            {u.email}
                          </span>
                        </span>
                        {u.role !== "student" && (
                          <span className="tag-aubade">{ROLE_LABEL[u.role] ?? u.role}</span>
                        )}
                      </Command.Item>
                    ))}
                  </Command.Group>
                )}

                {shown.courses.length > 0 && (
                  <Command.Group heading="Курсы" className={groupClass}>
                    {shown.courses.map((c) => (
                      <Command.Item
                        key={c.id}
                        value={`course:${c.id}`}
                        onSelect={() => go(`/admin/courses/${c.id}`)}
                        className={itemClass}
                      >
                        <span className="min-w-0 flex-1">
                          <span className="block truncate font-medium">{c.title}</span>
                          <span className="block truncate text-xs" style={{ color: "var(--muted-foreground)" }}>
                            {c.slug}
                          </span>
                        </span>
                        {!c.published && <span className="tag-aubade">черновик</span>}
                      </Command.Item>
                    ))}
                  </Command.Group>
                )}

                {shown.lessons.length > 0 && (
                  <Command.Group heading="Уроки" className={groupClass}>
                    {shown.lessons.map((l) => (
                      <Command.Item
                        key={l.id}
                        value={`lesson:${l.id}`}
                        onSelect={() =>
                          go(`/admin/courses/${l.courseId}/modules/${l.moduleId}/lessons/${l.id}`)
                        }
                        className={itemClass}
                      >
                        <span className="min-w-0 flex-1">
                          <span className="block truncate font-medium">{l.title}</span>
                          <span className="block truncate text-xs" style={{ color: "var(--muted-foreground)" }}>
                            {l.courseTitle}
                          </span>
                        </span>
                        {!l.published && <span className="tag-aubade">черновик</span>}
                      </Command.Item>
                    ))}
                  </Command.Group>
                )}

                {sections.length > 0 && (
                  <Command.Group heading="Разделы" className={groupClass}>
                    {sections.map((l) => (
                      <Command.Item
                        key={l.href}
                        value={`section:${l.href}`}
                        onSelect={() => go(l.href)}
                        className={itemClass}
                      >
                        {l.label}
                      </Command.Item>
                    ))}
                  </Command.Group>
                )}
              </Command.List>
            </Command>
          </DialogPrimitive.Popup>
        </DialogPrimitive.Portal>
      </DialogPrimitive.Root>
    </>
  );
}