'use client';

import { useState } from 'react';
import { usePathname } from 'next/navigation';
import Link from 'next/link';
import { useSession } from 'next-auth/react';
import { useTranslations } from 'next-intl';
import { motion, AnimatePresence } from 'framer-motion';
import {
  LayoutDashboard,
  Target,
  Users,
  Plug,
  Shield,
  Settings,
  ChevronLeft,
  ChevronRight,
  ChevronDown,
  ClipboardList,
  CalendarClock,
  GraduationCap,
  UserCog,
  Clock,
  CalendarDays,
  Network,
  Building2,
  UserPlus,
  type LucideIcon,
} from 'lucide-react';

import { cn } from '@/lib/utils';
import { Button } from '@/components/ui/button';
import { Separator } from '@/components/ui/separator';
import { Tooltip, TooltipContent, TooltipTrigger, TooltipProvider } from '@/components/ui/tooltip';
import { Collapsible, CollapsibleContent, CollapsibleTrigger } from '@/components/ui/collapsible';
import { useSidebarStore } from '@/stores/sidebar-store';
import type { UserRole } from '@/types';

/** Navigation item configuration with role-based access */
interface NavItem {
  key: string;
  href: string;
  icon: LucideIcon;
  requiredRoles?: UserRole[];
  children?: NavItem[];
  exactMatch?: boolean;
}

/** Main navigation structure with role requirements */
const mainNavItems: NavItem[] = [
  {
    key: 'dashboard',
    href: '/dashboard',
    icon: LayoutDashboard,
    // No requiredRoles = available to all authenticated users
  },
  {
    key: 'lean',
    href: '/lean',
    icon: Target,
    requiredRoles: ['employee', 'department_head', 'manager', 'admin'],
    children: [
      {
        key: 's3Planning',
        href: '/lean/s3-planning',
        icon: ClipboardList,
      },
      {
        key: 'morningMeeting',
        href: '/lean/morning-meeting',
        icon: CalendarClock,
      },
      {
        key: 'skillMatrix',
        href: '/lean/skill-matrix',
        icon: GraduationCap,
      },
    ],
  },
  {
    key: 'hr',
    href: '/hr',
    icon: Users,
    requiredRoles: ['department_head', 'manager', 'admin'],
    children: [
      {
        key: 'employees',
        href: '/hr/employees',
        icon: UserCog,
      },
      {
        key: 'timeTracking',
        href: '/hr/time-tracking',
        icon: Clock,
      },
      {
        key: 'absences',
        href: '/hr/absences',
        icon: CalendarDays,
      },
      {
        key: 'orgChart',
        href: '/hr/org-chart',
        icon: Network,
      },
    ],
  },
];

const bottomNavItems: NavItem[] = [
  {
    key: 'admin',
    href: '/admin',
    icon: Shield,
    requiredRoles: ['admin'],
    children: [
      {
        key: 'users',
        href: '/admin/users',
        icon: UserPlus,
      },
      {
        key: 'departments',
        href: '/admin/departments',
        icon: Building2,
      },
      {
        key: 'integrations',
        href: '/admin/integrations',
        icon: Plug,
      },
      {
        key: 'systemSettings',
        href: '/admin/settings',
        icon: Settings,
      },
    ],
  },
  {
    key: 'settings',
    href: '/settings',
    icon: Settings,
    // Available to all users
  },
];

interface SidebarProps {
  locale: string;
}

/**
 * Check if user has access to a navigation item based on roles
 */
function hasAccess(item: NavItem, userRoles: string[]): boolean {
  // If no roles required, everyone has access
  if (!item.requiredRoles || item.requiredRoles.length === 0) {
    return true;
  }
  // Check if user has any of the required roles
  return item.requiredRoles.some((role) => userRoles.includes(role));
}

/**
 * Filter navigation items based on user roles
 */
function filterNavItems(items: NavItem[], userRoles: string[]): NavItem[] {
  return items
    .filter((item) => hasAccess(item, userRoles))
    .map((item) => ({
      ...item,
      children: item.children?.filter((child) => hasAccess(child, userRoles)),
    }));
}

/**
 * Collapsible sidebar component with role-based navigation
 * - 240px when expanded
 * - 64px when collapsed (icons only)
 * - Sub-navigation for nested items
 */
export function Sidebar({ locale }: SidebarProps) {
  const pathname = usePathname();
  const { data: session } = useSession();
  const t = useTranslations('navigation');
  const { isExpanded, toggleSidebar } = useSidebarStore();

  // Get user roles, defaulting to empty array
  const userRoles = session?.user?.roles || [];

  // Filter navigation based on user roles
  const filteredMainNav = filterNavItems(mainNavItems, userRoles);
  const filteredBottomNav = filterNavItems(bottomNavItems, userRoles);

  const isActive = (href: string, exactMatch?: boolean) => {
    const localePath = `/${locale}${href}`;
    if (exactMatch) return pathname === localePath;
    return pathname === localePath || pathname.startsWith(`${localePath}/`);
  };

  const isParentActive = (item: NavItem) => {
    if (isActive(item.href)) return true;
    return item.children?.some((child) => isActive(child.href, child.exactMatch)) || false;
  };

  return (
    <TooltipProvider delayDuration={0}>
      <motion.aside
        initial={false}
        animate={{ width: isExpanded ? 240 : 64 }}
        transition={{ duration: 0.2, ease: 'easeInOut' }}
        className="fixed left-0 top-0 z-40 flex h-screen flex-col border-r border-sidebar-border bg-sidebar"
      >
        {/* Logo */}
        <div className="flex h-16 items-center justify-between px-4">
          <Link href={`/${locale}/dashboard`} className="flex items-center gap-2">
            <div className="flex h-8 w-8 items-center justify-center rounded-lg bg-primary text-primary-foreground font-bold">
              t
            </div>
            <AnimatePresence mode="wait">
              {isExpanded && (
                <motion.span
                  initial={{ opacity: 0, width: 0 }}
                  animate={{ opacity: 1, width: 'auto' }}
                  exit={{ opacity: 0, width: 0 }}
                  transition={{ duration: 0.2 }}
                  className="text-xl font-bold text-sidebar-foreground overflow-hidden"
                >
                  OS
                </motion.span>
              )}
            </AnimatePresence>
          </Link>
        </div>

        <Separator className="bg-sidebar-border" />

        {/* Main Navigation */}
        <nav className="flex-1 space-y-1 overflow-y-auto px-2 py-4">
          {filteredMainNav.map((item) => (
            <NavItemComponent
              key={item.key}
              item={item}
              locale={locale}
              isExpanded={isExpanded}
              isActive={isActive}
              isParentActive={isParentActive}
              t={t}
            />
          ))}
        </nav>

        <Separator className="bg-sidebar-border" />

        {/* Bottom Navigation */}
        <nav className="space-y-1 px-2 py-4">
          {filteredBottomNav.map((item) => (
            <NavItemComponent
              key={item.key}
              item={item}
              locale={locale}
              isExpanded={isExpanded}
              isActive={isActive}
              isParentActive={isParentActive}
              t={t}
            />
          ))}
        </nav>

        {/* Collapse Button */}
        <div className="border-t border-sidebar-border p-2">
          <Button
            variant="ghost"
            size="icon"
            onClick={toggleSidebar}
            className="w-full justify-center text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground"
          >
            {isExpanded ? (
              <ChevronLeft className="h-4 w-4" />
            ) : (
              <ChevronRight className="h-4 w-4" />
            )}
          </Button>
        </div>
      </motion.aside>
    </TooltipProvider>
  );
}

interface NavItemComponentProps {
  item: NavItem;
  locale: string;
  isExpanded: boolean;
  isActive: (href: string, exactMatch?: boolean) => boolean;
  isParentActive: (item: NavItem) => boolean;
  t: (key: string) => string;
}

function NavItemComponent({
  item,
  locale,
  isExpanded,
  isActive,
  isParentActive,
  t,
}: NavItemComponentProps) {
  const Icon = item.icon;
  const active = isActive(item.href, item.exactMatch);
  const parentActive = isParentActive(item);
  const hasChildren = item.children && item.children.length > 0;

  const [isOpen, setIsOpen] = useState(parentActive);

  // Simple link (no children)
  if (!hasChildren) {
    const linkContent = (
      <Link
        href={`/${locale}${item.href}`}
        className={cn(
          'flex items-center gap-3 rounded-lg px-3 py-2 text-sm font-medium transition-colors',
          active
            ? 'bg-sidebar-primary text-sidebar-primary-foreground'
            : 'text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground'
        )}
      >
        <Icon className="h-5 w-5 shrink-0" />
        {isExpanded && <span>{t(item.key)}</span>}
      </Link>
    );

    if (!isExpanded) {
      return (
        <Tooltip>
          <TooltipTrigger asChild>{linkContent}</TooltipTrigger>
          <TooltipContent side="right">{t(item.key)}</TooltipContent>
        </Tooltip>
      );
    }

    return linkContent;
  }

  // Collapsible item with children
  if (!isExpanded) {
    // When collapsed, show tooltip with sub-navigation
    return (
      <Tooltip>
        <TooltipTrigger asChild>
          <Link
            href={`/${locale}${item.href}`}
            className={cn(
              'flex items-center gap-3 rounded-lg px-3 py-2 text-sm font-medium transition-colors',
              parentActive
                ? 'bg-sidebar-primary text-sidebar-primary-foreground'
                : 'text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground'
            )}
          >
            <Icon className="h-5 w-5 shrink-0" />
          </Link>
        </TooltipTrigger>
        <TooltipContent side="right" className="flex flex-col gap-1 p-2">
          <span className="font-medium">{t(item.key)}</span>
          <Separator className="my-1" />
          {item.children?.map((child) => (
            <Link
              key={child.key}
              href={`/${locale}${child.href}`}
              className={cn(
                'rounded px-2 py-1 text-sm transition-colors hover:bg-accent',
                isActive(child.href, child.exactMatch) && 'bg-accent font-medium'
              )}
            >
              {t(child.key)}
            </Link>
          ))}
        </TooltipContent>
      </Tooltip>
    );
  }

  // Expanded collapsible
  return (
    <Collapsible open={isOpen} onOpenChange={setIsOpen}>
      <CollapsibleTrigger asChild>
        <button
          className={cn(
            'flex w-full items-center gap-3 rounded-lg px-3 py-2 text-sm font-medium transition-colors',
            parentActive
              ? 'bg-sidebar-accent text-sidebar-accent-foreground'
              : 'text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground'
          )}
        >
          <Icon className="h-5 w-5 shrink-0" />
          <span className="flex-1 text-left">{t(item.key)}</span>
          <motion.div
            animate={{ rotate: isOpen ? 180 : 0 }}
            transition={{ duration: 0.2 }}
          >
            <ChevronDown className="h-4 w-4" />
          </motion.div>
        </button>
      </CollapsibleTrigger>

      <CollapsibleContent>
        <motion.div
          initial={{ opacity: 0 }}
          animate={{ opacity: 1 }}
          exit={{ opacity: 0 }}
          className="ml-4 mt-1 space-y-1 border-l border-sidebar-border pl-4"
        >
          {item.children?.map((child) => {
            const ChildIcon = child.icon;
            const childActive = isActive(child.href, child.exactMatch);

            return (
              <Link
                key={child.key}
                href={`/${locale}${child.href}`}
                className={cn(
                  'flex items-center gap-3 rounded-lg px-3 py-2 text-sm transition-colors',
                  childActive
                    ? 'bg-sidebar-primary text-sidebar-primary-foreground'
                    : 'text-sidebar-foreground hover:bg-sidebar-accent hover:text-sidebar-accent-foreground'
                )}
              >
                <ChildIcon className="h-4 w-4 shrink-0" />
                <span>{t(child.key)}</span>
              </Link>
            );
          })}
        </motion.div>
      </CollapsibleContent>
    </Collapsible>
  );
}