"use client";

import * as React from "react";
import Link from "next/link";
import { usePathname } from "next/navigation";
import { Disclosure, DisclosureButton, DisclosurePanel } from "@headlessui/react";
import { ChevronRight, PanelLeftClose, PanelLeftOpen } from "lucide-react";

export type AdminNavItem = {
  label: string;
  href: string;
  icon?: React.ReactNode;
};

export type AdminNavGroup = {
  label: string;
  icon?: React.ReactNode;
  items: AdminNavItem[];
};

function cx(...classes: Array<string | false | undefined | null>) {
  return classes.filter(Boolean).join(" ");
}

function isActiveRoute(pathname: string, href: string) {
  // Exact match for /admin, prefix match for nested pages
  if (href === "/admin") return pathname === "/admin";
  return pathname === href || pathname.startsWith(`${href}/`);
}

function groupHasActiveItem(pathname: string, group: AdminNavGroup) {
  return group.items.some((i) => isActiveRoute(pathname, i.href));
}

export default function AdminLeftNavigation({
  collapsed,
  onToggleCollapsed,
  groups,
}: {
  collapsed: boolean;
  onToggleCollapsed: () => void;
  groups: AdminNavGroup[];
}) {
  const pathname = usePathname() || "/admin";

  return (
    <aside
      className={cx(
        "fixed left-0 flex shrink-0 flex-col border-r border-zinc-900 bg-zinc-950/60 backdrop-blur z-40",
        collapsed ? "w-[68px]" : "w-[280px]"
      )}
      style={{ top: '52px', height: 'calc(100vh - 52px)' }}
    >
      {/* Header / Brand */}
      <div className={cx("flex items-center justify-between px-3 py-3", collapsed && "justify-center")}>
        <div className={cx("flex items-center gap-2", collapsed && "hidden")}>
          <div className="h-8 w-8 rounded-lg bg-zinc-900/70 ring-1 ring-zinc-800" />
          <div className="leading-tight">
            <div className="text-xs uppercase tracking-[0.22em] text-zinc-500">
              Battl
            </div>
            <div className="text-sm font-medium text-zinc-100">
              Admin
            </div>
          </div>
        </div>

        <button
          type="button"
          onClick={onToggleCollapsed}
          className={cx(
            "inline-flex h-9 w-9 items-center justify-center rounded-md border border-zinc-800 bg-zinc-900/40 text-zinc-200 hover:bg-zinc-900/70",
            collapsed && "mx-auto"
          )}
          aria-label={collapsed ? "Expand sidebar" : "Collapse sidebar"}
          title={collapsed ? "Expand" : "Collapse"}
        >
          {collapsed ? (
            <PanelLeftOpen className="h-4 w-4" />
          ) : (
            <PanelLeftClose className="h-4 w-4" />
          )}
        </button>
      </div>

      {/* Nav */}
      <nav className="flex-1 overflow-y-auto px-2 pb-3">
        <ul className="space-y-1">
          {groups.map((group) => {
            const defaultOpen = groupHasActiveItem(pathname, group);

            // In collapsed mode, we render items as a flat icon list (no accordion)
            if (collapsed) {
              return (
                <li key={group.label} className="pt-1">
                  <div className="my-2 h-px bg-zinc-900" />
                  <div className="flex flex-col gap-1">
                    {group.items.map((item) => {
                      const active = isActiveRoute(pathname, item.href);
                      return (
                        <Link
                          key={item.href}
                          href={item.href}
                          title={`${group.label} → ${item.label}`}
                          className={cx(
                            "flex h-10 items-center justify-center rounded-md border border-transparent",
                            active
                              ? "bg-white/5 text-white ring-1 ring-zinc-800"
                              : "text-zinc-400 hover:bg-white/5 hover:text-zinc-200"
                          )}
                        >
                          <span className="inline-flex">{item.icon}</span>
                        </Link>
                      );
                    })}
                  </div>
                </li>
              );
            }

            return (
              <li key={group.label}>
                <Disclosure defaultOpen={defaultOpen}>
                  {({ open }) => (
                    <>
                      <DisclosureButton
                        className={cx(
                          "group flex w-full items-center justify-between rounded-md px-2 py-2 text-left text-xs font-semibold uppercase tracking-[0.18em]",
                          open ? "bg-white/5 text-zinc-100" : "text-zinc-400 hover:bg-white/5 hover:text-zinc-200"
                        )}
                      >
                        <span className="flex items-center gap-2">
                          <span className="inline-flex text-zinc-400 group-hover:text-zinc-200">
                            {group.icon}
                          </span>
                          {group.label}
                        </span>

                        <ChevronRight
                          className={cx(
                            "h-4 w-4 text-zinc-500 transition-transform",
                            open && "rotate-90"
                          )}
                        />
                      </DisclosureButton>

                      <DisclosurePanel className="mt-1 space-y-1 pl-1">
                        {group.items.map((item) => {
                          const active = isActiveRoute(pathname, item.href);
                          return (
                            <Link
                              key={item.href}
                              href={item.href}
                              className={cx(
                                "flex items-center gap-2 rounded-md px-2 py-2 text-sm",
                                active
                                  ? "bg-white/5 text-white ring-1 ring-zinc-800"
                                  : "text-zinc-300 hover:bg-white/5 hover:text-white"
                              )}
                            >
                              <span className="inline-flex h-5 w-5 items-center justify-center text-zinc-400">
                                {item.icon}
                              </span>
                              <span className="truncate">{item.label}</span>
                            </Link>
                          );
                        })}
                      </DisclosurePanel>
                    </>
                  )}
                </Disclosure>
              </li>
            );
          })}
        </ul>
      </nav>

      {/* Footer */}
      <div className={cx("border-t border-zinc-900 p-3", collapsed && "px-2")}>
        <div
          className={cx(
            "flex items-center gap-3 rounded-md bg-zinc-900/30 px-3 py-2 ring-1 ring-zinc-800",
            collapsed && "justify-center px-2"
          )}
          title="Admin user"
        >
          <div className="h-8 w-8 rounded-full bg-zinc-900 ring-1 ring-zinc-800" />
          {!collapsed && (
            <div className="min-w-0">
              <div className="text-xs uppercase tracking-[0.18em] text-zinc-500">
                Internal
              </div>
              <div className="truncate text-sm text-zinc-200">ADMIN</div>
            </div>
          )}
        </div>
      </div>
    </aside>
  );
}