'use client';

import { useState, useEffect } from 'react';
import Link from 'next/link';
import { usePathname, useRouter } from 'next/navigation';
import {
  LayoutDashboard,
  Activity,
  BarChart3,
  Cpu,
  Key,
  Code2,
  Settings,
  LogOut,
  Menu,
  X,
  Sun,
  Moon,
  HeartPulse,
  Sparkles,
  Server,
} from 'lucide-react';
import { useAuth } from '@/lib/auth';

const navItems = [
  { href: '/', label: 'Dashboard', icon: LayoutDashboard },
  { href: '/hermes', label: 'Hermes', icon: Sparkles },
  { href: '/health', label: 'Health', icon: HeartPulse },
  { href: '/metrics', label: 'Metrics', icon: BarChart3 },
  { href: '/vm', label: 'VM Health', icon: Server },
  { href: '/system', label: 'System', icon: Cpu },
  { href: '/env', label: 'Environment', icon: Key },
  { href: '/code-quality', label: 'Code Quality', icon: Code2 },
  { href: '/settings/cosmos', label: 'Settings', icon: Settings },
];

export function SidebarNav() {
  const pathname = usePathname();
  const router = useRouter();
  const { user, logout } = useAuth();
  const [mobileOpen, setMobileOpen] = useState(false);
  const [theme, setTheme] = useState<'light' | 'dark'>('light');

  // Sync theme from localStorage on mount
  useEffect(() => {
    const saved = (localStorage.getItem('theme') as 'light' | 'dark') || 'light';
    setTheme(saved);
    document.documentElement.classList.toggle('dark', saved === 'dark');
  }, []);

  const handleLogout = () => {
    logout();
    router.push('/login');
  };

  const initials = user?.email
    ? user.email.slice(0, 2).toUpperCase()
    : '??';

  const sidebarContent = (
    <>
      {/* Logo */}
      <div className="flex h-16 items-center justify-between border-b px-6">
        <div className="flex items-center gap-2">
          <div className="flex h-8 w-8 items-center justify-center rounded-lg bg-blue-600">
            <LayoutDashboard className="h-4 w-4 text-white" />
          </div>
          <div>
            <h1 className="text-sm font-bold">DevOps</h1>
            <p className="text-[10px] text-gray-500">Dashboard</p>
          </div>
        </div>
        {/* Mobile close button */}
        <button
          className="md:hidden text-gray-500 hover:text-gray-700"
          onClick={() => setMobileOpen(false)}
        >
          <X className="h-5 w-5" />
        </button>
      </div>

      {/* Navigation */}
      <nav className="flex-1 space-y-1 px-3 py-4">
        {navItems.map(item => {
          const isActive = pathname === item.href ||
            (item.href !== '/' && pathname.startsWith(item.href));
          return (
            <Link
              key={item.href}
              href={item.href}
              onClick={() => setMobileOpen(false)}
              className={`flex items-center gap-3 rounded-lg px-3 py-2 text-sm font-medium transition-colors ${
                isActive
                  ? 'bg-blue-600 text-white'
                  : 'text-gray-700 hover:bg-gray-100'
              }`}
            >
              <item.icon className="h-4 w-4" />
              <span>{item.label}</span>
            </Link>
          );
        })}
      </nav>

      {/* Footer — theme toggle + user info + logout */}
      <div className="border-t p-4 space-y-3">
        <button
          onClick={() => {
            const next = theme === 'dark' ? 'light' : 'dark';
            setTheme(next);
            localStorage.setItem('theme', next);
            document.documentElement.classList.toggle('dark', next === 'dark');
          }}
          className="flex w-full items-center gap-3 rounded-lg px-3 py-2 text-sm text-gray-700 hover:bg-gray-100 transition-colors"
        >
          {theme === 'dark' ? <Sun className="h-4 w-4" /> : <Moon className="h-4 w-4" />}
          {theme === 'dark' ? 'Light Mode' : 'Dark Mode'}
        </button>
        <div className="flex items-center gap-3">
          <div className="flex h-8 w-8 items-center justify-center rounded-full bg-gray-200 text-xs font-bold text-gray-700">
            {initials}
          </div>
          <div className="flex-1 min-w-0">
            <p className="text-sm font-medium truncate text-gray-900">{user?.email ?? 'Admin'}</p>
            <p className="text-xs text-gray-500 truncate">{user?.role ?? 'admin'}</p>
          </div>
          <button
            onClick={handleLogout}
            title="Sign out"
            aria-label="Sign out"
            className="text-gray-500 hover:text-gray-700"
          >
            <LogOut className="h-4 w-4" />
          </button>
        </div>
      </div>
    </>
  );

  return (
    <>
      {/* Mobile hamburger */}
      <div className="fixed top-0 left-0 right-0 z-30 flex h-14 items-center border-b bg-white px-4 md:hidden">
        <button onClick={() => setMobileOpen(true)}>
          <Menu className="h-6 w-6" />
        </button>
        <span className="ml-3 text-sm font-bold">DevOps Dashboard</span>
      </div>
      {/* Spacer for mobile top bar */}
      <div className="h-14 md:hidden" />

      {/* Mobile overlay */}
      {mobileOpen && (
        <div
          className="fixed inset-0 z-40 bg-black/50 md:hidden"
          onClick={() => setMobileOpen(false)}
        />
      )}

      {/* Sidebar — static on desktop, fixed on mobile */}
      <aside
        className={`hidden md:flex md:w-64 md:shrink-0 md:flex-col md:border-r md:bg-white fixed inset-y-0 left-0 z-50 flex w-64 flex-col border-r bg-white transition-transform duration-200 translate-x-[-100%] md:translate-x-0 ${mobileOpen ? 'translate-x-0' : ''}`}
      >
        {sidebarContent}
      </aside>
    </>
  );
}