"use client";

import { useState, useEffect } from "react";
import Link from "next/link";
import { usePathname } from "next/navigation";
import { ChevronDown, Menu, X } from "lucide-react";
import { cn } from "@/lib/utils";

export type NavLeaf = { href: string; label: string };
export type NavItem =
  | { kind: "link"; href: string; label: string; icon: React.ReactNode }
  | { kind: "group"; label: string; icon: React.ReactNode; children: NavLeaf[] };

export function Sidebar({ items }: { items: NavItem[] }) {
  const pathname = usePathname();
  const [mobileOpen, setMobileOpen] = useState(false);

  // Close drawer on navigation
  useEffect(() => {
    setMobileOpen(false);
  }, [pathname]);

  // Lock body scroll when drawer is open
  useEffect(() => {
    document.body.style.overflow = mobileOpen ? "hidden" : "";
    return () => {
      document.body.style.overflow = "";
    };
  }, [mobileOpen]);

  const renderNav = (onNavigate?: () => void) => (
    <nav className="p-3 space-y-0.5 text-sm">
      {items.map((item, i) =>
        item.kind === "link" ? (
          <LeafLink
            key={i}
            href={item.href}
            label={item.label}
            icon={item.icon}
            active={pathname === item.href || (item.href !== "/" && pathname.startsWith(item.href))}
            onClick={onNavigate}
          />
        ) : (
          <Group
            key={i}
            item={item}
            active={pathname.startsWith(item.children[0]?.href.split("/").slice(0, 3).join("/") ?? "")}
          />
        )
      )}
    </nav>
  );

  return (
    <>
      {/* Desktop: persistent sidebar (hidden on mobile) */}
      <aside className="hidden lg:block w-64 shrink-0 bg-white dark:bg-[#0f1419] border-r border-gray-200 dark:border-white/5 min-h-[calc(100vh-4rem)]">
        {renderNav()}
      </aside>

      {/* Mobile: hamburger in the top bar triggers a drawer */}
      <button
        type="button"
        onClick={() => setMobileOpen(true)}
        aria-label="Open navigation"
        className="lg:hidden w-9 h-9 grid place-items-center rounded-lg hover:bg-gray-100 dark:hover:bg-white/5 text-gray-500 dark:text-gray-400"
      >
        <Menu className="w-5 h-5" />
      </button>

      {mobileOpen && (
        <div
          className="lg:hidden fixed inset-0 z-40 bg-black/40"
          onClick={() => setMobileOpen(false)}
        />
      )}
      <aside
        className={cn(
          "lg:hidden fixed top-0 left-0 bottom-0 z-50 w-72 bg-white dark:bg-[#0f1419] shadow-2xl transition-transform",
          mobileOpen ? "translate-x-0" : "-translate-x-full"
        )}
      >
        <div className="flex items-center justify-between px-4 h-16 border-b border-gray-200 dark:border-white/5">
          <div className="flex items-center gap-2">
            <img src="/brand/logo.png" alt="Mega Plant" className="w-8 h-8 rounded-xl object-contain bg-white dark:bg-[#0b1014] shadow-sm" />
            <span className="text-sm font-semibold text-[#003D5B] dark:text-white">Mega Plant</span>
          </div>
          <button
            type="button"
            onClick={() => setMobileOpen(false)}
            aria-label="Close navigation"
            className="w-9 h-9 grid place-items-center rounded-lg hover:bg-gray-100 dark:hover:bg-white/5 text-gray-500 dark:text-gray-400"
          >
            <X className="w-5 h-5" />
          </button>
        </div>
        {renderNav(() => setMobileOpen(false))}
      </aside>
    </>
  );
}

function LeafLink({
  href, label, icon, active, onClick,
}: {
  href: string; label: string; icon: React.ReactNode; active: boolean; onClick?: () => void;
}) {
  return (
    <Link
      href={href}
      onClick={onClick}
      className={cn(
        "flex items-center gap-3 px-3 py-2 rounded-lg font-medium transition",
        active
          ? "bg-gradient-to-r from-[#30638E]/10 to-[#00798C]/5 text-[#003D5B] dark:from-[#30638E]/20 dark:to-[#00798C]/10 dark:text-white"
          : "text-gray-600 dark:text-gray-400 hover:bg-gray-50 dark:hover:bg-white/5 hover:text-gray-900 dark:hover:text-white"
      )}
    >
      <span className={cn(active ? "text-[#30638E] dark:text-[#00798C]" : "text-gray-400")}>{icon}</span>
      <span>{label}</span>
    </Link>
  );
}

function Group({ item, active }: { item: Extract<NavItem, { kind: "group" }>; active: boolean }) {
  const [open, setOpen] = useState(active);
  const pathname = usePathname();
  return (
    <div>
      <button
        onClick={() => setOpen((o) => !o)}
        className={cn(
          "w-full flex items-center gap-3 px-3 py-2 rounded-lg font-medium transition",
          active
            ? "text-[#003D5B] dark:text-white"
            : "text-gray-600 dark:text-gray-400 hover:bg-gray-50 dark:hover:bg-white/5 hover:text-gray-900 dark:hover:text-white"
        )}
      >
        <span className={cn(active ? "text-[#30638E] dark:text-[#00798C]" : "text-gray-400")}>{item.icon}</span>
        <span className="flex-1 text-left">{item.label}</span>
        <ChevronDown className={cn("w-4 h-4 text-gray-400 transition-transform", open && "rotate-180")} />
      </button>
      {open && (
        <div className="ml-7 mt-0.5 space-y-0.5 border-l-2 border-gray-100 dark:border-white/5 pl-2">
          {item.children.map((child) => {
            const childActive = pathname === child.href;
            return (
              <Link
                key={child.href}
                href={child.href}
                className={cn(
                  "block px-3 py-1.5 rounded-lg text-xs font-medium transition",
                  childActive
                    ? "bg-[#30638E]/10 text-[#30638E] dark:bg-[#00798C]/15 dark:text-[#00798C]"
                    : "text-gray-500 dark:text-gray-400 hover:bg-gray-50 dark:hover:bg-white/5 hover:text-gray-900 dark:hover:text-white"
                )}
              >
                {child.label}
              </Link>
            );
          })}
        </div>
      )}
    </div>
  );
}