import { useState, useEffect } from "react";
import { NavLink, useLocation } from "react-router-dom";
import { useQuery } from "@tanstack/react-query";
import {
  Home,
  Grid2X2,
  Settings,
  ShieldCheck,
  ChevronRight,
  ChevronLeft,
  ChevronDown,
  LogOut,
  UserCircle,
  FileText,
  Folder,
  Users,
  UsersRound,
  Palette,
} from "lucide-react";
import { Button } from "@/components/ui/button";
import ThemeToggle from "@/components/ThemeToggle";
import { useAuth } from "@/hooks/useAuth";
import { getMe, listCategories } from "@/api/client";
import { cn } from "@/lib/utils";

export default function Sidebar() {
  const [sidebarExpanded, setSidebarExpanded] = useState(true);
  const { logout } = useAuth();
  const location = useLocation();
  const { data: user } = useQuery({ queryKey: ["me"], queryFn: getMe });

  const isAppsRoute = location.pathname.startsWith("/apps");
  const isDocsRoute = location.pathname.startsWith("/apps/documents");
  const isAdminRoute = location.pathname.startsWith("/admin");

  const [appsOpen, setAppsOpen] = useState(isAppsRoute);
  const [docsOpen, setDocsOpen] = useState(isDocsRoute);
  const [adminOpen, setAdminOpen] = useState(isAdminRoute);

  // Auto-open sections when navigating to their routes
  useEffect(() => {
    if (isAppsRoute) setAppsOpen(true);
  }, [isAppsRoute]);

  useEffect(() => {
    if (isDocsRoute) setDocsOpen(true);
  }, [isDocsRoute]);

  useEffect(() => {
    if (isAdminRoute) setAdminOpen(true);
  }, [isAdminRoute]);

  const { data: categories = [] } = useQuery({
    queryKey: ["categories"],
    queryFn: listCategories,
    enabled: appsOpen && docsOpen && !!user,
  });

  const navItemClass = (isActive: boolean) =>
    cn(
      "flex items-center rounded-lg transition-colors",
      sidebarExpanded ? "px-3 py-2 gap-3" : "justify-center py-3",
      isActive
        ? "bg-primary/10 text-primary"
        : "text-muted hover:bg-muted/20 hover:text-foreground"
    );

  const subItemClass = (isActive: boolean) =>
    cn(
      "flex items-center rounded-lg transition-colors text-sm",
      "pl-8 pr-3 py-1.5 gap-2",
      isActive
        ? "bg-primary/10 text-primary"
        : "text-muted hover:bg-muted/20 hover:text-foreground"
    );

  const subSubItemClass = (isActive: boolean) =>
    cn(
      "flex items-center rounded-lg transition-colors text-sm",
      "pl-12 pr-3 py-1 gap-2",
      isActive
        ? "bg-primary/10 text-primary"
        : "text-muted hover:bg-muted/20 hover:text-foreground"
    );

  return (
    <aside
      className={cn(
        "flex flex-col h-screen bg-surface border-r border-border transition-all duration-200 shrink-0",
        sidebarExpanded ? "w-56" : "w-16"
      )}
    >
      <nav className="flex-1 py-4 px-2 space-y-1 overflow-y-auto overflow-x-hidden">
        {/* Home */}
        <NavLink
          to="/"
          end
          className={({ isActive }) => navItemClass(isActive)}
        >
          <Home className="h-5 w-5 shrink-0" />
          {sidebarExpanded && (
            <span className="text-sm font-medium whitespace-nowrap">Home</span>
          )}
        </NavLink>

        {/* Apps — expandable */}
        <div>
          {sidebarExpanded ? (
            <div
              className={cn(
                "flex items-center rounded-lg transition-colors",
                isAppsRoute
                  ? "bg-primary/10 text-primary"
                  : "text-muted hover:bg-muted/20 hover:text-foreground"
              )}
            >
              <NavLink
                to="/apps"
                end
                className="flex items-center gap-3 px-3 py-2 flex-1 min-w-0"
              >
                <Grid2X2 className="h-5 w-5 shrink-0" />
                <span className="text-sm font-medium whitespace-nowrap">Apps</span>
              </NavLink>
              <button
                onClick={() => setAppsOpen((o) => !o)}
                className="px-2 py-2 rounded-r-lg"
                aria-label={appsOpen ? "Collapse apps" : "Expand apps"}
              >
                {appsOpen ? (
                  <ChevronDown className="h-4 w-4 shrink-0" />
                ) : (
                  <ChevronRight className="h-4 w-4 shrink-0" />
                )}
              </button>
            </div>
          ) : (
            <NavLink
              to="/apps"
              end
              className={({ isActive }) => navItemClass(isActive)}
            >
              <Grid2X2 className="h-5 w-5 shrink-0" />
            </NavLink>
          )}

          {/* Apps sub-items — only when sidebar is expanded and appsOpen */}
          {sidebarExpanded && appsOpen && (
            <div className="mt-0.5 space-y-0.5">
              {/* Documents service */}
              <div>
                <div
                  className={cn(
                    "flex items-center rounded-lg transition-colors text-sm",
                    isDocsRoute
                      ? "bg-primary/10 text-primary"
                      : "text-muted hover:bg-muted/20 hover:text-foreground"
                  )}
                >
                  <NavLink
                    to="/apps/documents"
                    end
                    className="flex items-center gap-2 pl-8 pr-2 py-1.5 flex-1 min-w-0"
                  >
                    <FileText className="h-4 w-4 shrink-0" />
                    <span className="whitespace-nowrap">Documents</span>
                  </NavLink>
                  <button
                    onClick={() => setDocsOpen((o) => !o)}
                    className="px-2 py-1.5 rounded-r-lg"
                    aria-label={docsOpen ? "Collapse documents" : "Expand documents"}
                  >
                    {docsOpen ? (
                      <ChevronDown className="h-3.5 w-3.5 shrink-0" />
                    ) : (
                      <ChevronRight className="h-3.5 w-3.5 shrink-0" />
                    )}
                  </button>
                </div>

                {/* Categories */}
                {docsOpen && (
                  <div className="mt-0.5 space-y-0.5">
                    {categories.map((cat) => (
                      <NavLink
                        key={cat.id}
                        to={`/apps/documents?category_id=${cat.id}`}
                        className={({ isActive }) => subSubItemClass(isActive)}
                      >
                        <Folder className="h-3.5 w-3.5 shrink-0" />
                        <span className="whitespace-nowrap truncate">{cat.name}</span>
                      </NavLink>
                    ))}
                  </div>
                )}
              </div>
            </div>
          )}
        </div>

        {/* Settings */}
        <NavLink
          to="/settings"
          className={({ isActive }) => navItemClass(isActive)}
        >
          <Settings className="h-5 w-5 shrink-0" />
          {sidebarExpanded && (
            <span className="text-sm font-medium whitespace-nowrap">Settings</span>
          )}
        </NavLink>

        {/* Admin — expandable */}
        {user?.is_admin && (
          <div>
            {sidebarExpanded ? (
              <div
                className={cn(
                  "flex items-center rounded-lg transition-colors",
                  isAdminRoute
                    ? "bg-primary/10 text-primary"
                    : "text-muted hover:bg-muted/20 hover:text-foreground"
                )}
              >
                <NavLink
                  to="/admin/users"
                  className="flex items-center gap-3 px-3 py-2 flex-1 min-w-0"
                >
                  <ShieldCheck className="h-5 w-5 shrink-0" />
                  <span className="text-sm font-medium whitespace-nowrap">Admin</span>
                </NavLink>
                <button
                  onClick={() => setAdminOpen((o) => !o)}
                  className="px-2 py-2 rounded-r-lg"
                  aria-label={adminOpen ? "Collapse admin" : "Expand admin"}
                >
                  {adminOpen ? (
                    <ChevronDown className="h-4 w-4 shrink-0" />
                  ) : (
                    <ChevronRight className="h-4 w-4 shrink-0" />
                  )}
                </button>
              </div>
            ) : (
              <NavLink
                to="/admin/users"
                className={({ isActive }) => navItemClass(isActive)}
              >
                <ShieldCheck className="h-5 w-5 shrink-0" />
              </NavLink>
            )}

            {/* Admin sub-items */}
            {sidebarExpanded && adminOpen && (
              <div className="mt-0.5 space-y-0.5">
                <NavLink
                  to="/admin/users"
                  className={({ isActive }) => subItemClass(isActive)}
                >
                  <Users className="h-4 w-4 shrink-0" />
                  <span className="whitespace-nowrap">Users</span>
                </NavLink>
                <NavLink
                  to="/admin/groups"
                  className={({ isActive }) => subItemClass(isActive)}
                >
                  <UsersRound className="h-4 w-4 shrink-0" />
                  <span className="whitespace-nowrap">Groups</span>
                </NavLink>
                <NavLink
                  to="/admin/appearance"
                  className={({ isActive }) => subItemClass(isActive)}
                >
                  <Palette className="h-4 w-4 shrink-0" />
                  <span className="whitespace-nowrap">Appearance</span>
                </NavLink>
              </div>
            )}
          </div>
        )}
      </nav>

      {/* Bottom section */}
      <div className="py-4 px-2 space-y-1 border-t border-border">
        <div
          className={cn(
            "flex items-center rounded-lg py-2 text-muted",
            sidebarExpanded ? "px-3 gap-3" : "justify-center"
          )}
        >
          <UserCircle className="h-5 w-5 shrink-0" />
          {sidebarExpanded && user && (
            <span className="text-sm font-medium truncate">{user.email}</span>
          )}
        </div>

        <div className={cn("flex", sidebarExpanded ? "px-1" : "justify-center")}>
          <ThemeToggle />
        </div>

        <Button
          variant="ghost"
          className={cn(
            "w-full text-muted hover:text-foreground",
            sidebarExpanded ? "justify-start px-3 gap-3" : "justify-center px-0"
          )}
          onClick={logout}
        >
          <LogOut className="h-5 w-5 shrink-0" />
          {sidebarExpanded && <span className="text-sm font-medium">Logout</span>}
        </Button>

        <Button
          variant="ghost"
          size="icon"
          className={cn("w-full text-muted hover:text-foreground", !sidebarExpanded && "px-0")}
          onClick={() => setSidebarExpanded((e) => !e)}
          aria-label={sidebarExpanded ? "Collapse sidebar" : "Expand sidebar"}
        >
          {sidebarExpanded ? (
            <ChevronLeft className="h-5 w-5" />
          ) : (
            <ChevronRight className="h-5 w-5" />
          )}
        </Button>
      </div>
    </aside>
  );
}