import { useState, useMemo } from 'react';
import {
  Box,
  Collapse,
  Drawer,
  IconButton,
  List,
  ListItem,
  ListItemButton,
  ListItemIcon,
  ListItemText,
  Toolbar,
  Tooltip,
} from '@mui/material';
import {
  Dashboard as DashboardIcon,
  DirectionsCar,
  Build,
  People,
  Air,
  CalendarMonth,
  MenuBook,
  AdminPanelSettings,
  Settings,
  Menu as MenuIcon,
  ExpandMore,
  ExpandLess,
} from '@mui/icons-material';
import { useNavigate, useLocation } from 'react-router-dom';
import { useQuery } from '@tanstack/react-query';
import { useLayout, DRAWER_WIDTH, DRAWER_WIDTH_COLLAPSED } from '../../contexts/LayoutContext';
import { useAuth } from '../../contexts/AuthContext';
import { vehiclesApi } from '../../services/vehicles';

export { DRAWER_WIDTH, DRAWER_WIDTH_COLLAPSED };

interface SubItem {
  text: string;
  path: string;
}

interface NavigationItem {
  text: string;
  icon: JSX.Element;
  path: string;
  subItems?: SubItem[];
}

const kalenderSubItems: SubItem[] = [
  { text: 'Veranstaltungen', path: '/kalender?tab=0' },
  { text: 'Fahrzeugbuchungen', path: '/kalender?tab=1' },
];

const adminSubItems: SubItem[] = [
  { text: 'Services', path: '/admin?tab=0' },
  { text: 'System', path: '/admin?tab=1' },
  { text: 'Benutzer', path: '/admin?tab=2' },
  { text: 'Broadcast', path: '/admin?tab=3' },
  { text: 'Banner', path: '/admin?tab=4' },
  { text: 'Wartung', path: '/admin?tab=5' },
];

const baseNavigationItems: NavigationItem[] = [
  {
    text: 'Dashboard',
    icon: <DashboardIcon />,
    path: '/dashboard',
  },
  {
    text: 'Kalender',
    icon: <CalendarMonth />,
    path: '/kalender',
    subItems: kalenderSubItems,
  },
  {
    text: 'Fahrzeuge',
    icon: <DirectionsCar />,
    path: '/fahrzeuge',
  },
  {
    text: 'Ausrüstung',
    icon: <Build />,
    path: '/ausruestung',
  },
  {
    text: 'Mitglieder',
    icon: <People />,
    path: '/mitglieder',
  },
  {
    text: 'Atemschutz',
    icon: <Air />,
    path: '/atemschutz',
  },
  {
    text: 'Wissen',
    icon: <MenuBook />,
    path: '/wissen',
  },
];

const adminItem: NavigationItem = {
  text: 'Admin',
  icon: <AdminPanelSettings />,
  path: '/admin',
  subItems: adminSubItems,
};

const adminSettingsItem: NavigationItem = {
  text: 'Einstellungen',
  icon: <Settings />,
  path: '/admin/settings',
};

interface SidebarProps {
  mobileOpen: boolean;
  onMobileClose: () => void;
}

function Sidebar({ mobileOpen, onMobileClose }: SidebarProps) {
  const navigate = useNavigate();
  const location = useLocation();
  const { sidebarCollapsed, toggleSidebar } = useLayout();
  const { user } = useAuth();

  const isAdmin = user?.groups?.includes('dashboard_admin') ?? false;

  // Fetch vehicle list for dynamic dropdown sub-items
  const { data: vehicleList } = useQuery({
    queryKey: ['vehicles', 'sidebar'],
    queryFn: () => vehiclesApi.getAll(),
    staleTime: 2 * 60 * 1000,
  });

  const vehicleSubItems: SubItem[] = useMemo(
    () =>
      (vehicleList ?? []).map((v) => ({
        text: v.bezeichnung ?? v.kurzname,
        path: `/fahrzeuge/${v.id}`,
      })),
    [vehicleList],
  );

  const navigationItems = useMemo((): NavigationItem[] => {
    const fahrzeugeItem: NavigationItem = {
      text: 'Fahrzeuge',
      icon: <DirectionsCar />,
      path: '/fahrzeuge',
      subItems: vehicleSubItems.length > 0 ? vehicleSubItems : undefined,
    };
    const items = baseNavigationItems.map((item) =>
      item.path === '/fahrzeuge' ? fahrzeugeItem : item,
    );
    return isAdmin ? [...items, adminItem, adminSettingsItem] : items;
  }, [isAdmin, vehicleSubItems]);

  // Expand state for items with sub-items — auto-expand when route matches
  const [expandedItems, setExpandedItems] = useState<Record<string, boolean>>({});

  const isExpanded = (item: NavigationItem) => {
    if (expandedItems[item.path] !== undefined) return expandedItems[item.path];
    // Auto-expand when the current route matches
    return location.pathname === item.path || location.pathname.startsWith(item.path + '/');
  };

  const toggleExpand = (path: string) => {
    setExpandedItems((prev) => ({ ...prev, [path]: !isExpanded({ path } as NavigationItem) }));
  };

  const handleNavigation = (path: string) => {
    navigate(path);
    onMobileClose();
  };

  const drawerContent = (
    <Box sx={{ display: 'flex', flexDirection: 'column', height: '100%' }}>
      <Toolbar />
      <Box sx={{ display: 'flex', justifyContent: sidebarCollapsed ? 'center' : 'flex-end', px: 1, py: 0.5 }}>
        <IconButton onClick={toggleSidebar} aria-label="Sidebar umschalten">
          <MenuIcon />
        </IconButton>
      </Box>
      <List sx={{ flex: 1 }}>
        {navigationItems.map((item) => {
          const isActive = location.pathname === item.path;
          const hasSubItems = item.subItems && item.subItems.length > 0;
          const expanded = hasSubItems && isExpanded(item);
          return (
            <Box key={item.text}>
              <ListItem disablePadding>
                <Tooltip
                  title={item.text}
                  placement="right"
                  arrow
                  disableHoverListener={!sidebarCollapsed}
                >
                  <ListItemButton
                    selected={isActive}
                    onClick={() => handleNavigation(item.path)}
                    aria-label={`Zu ${item.text} navigieren`}
                    sx={{
                      justifyContent: sidebarCollapsed ? 'center' : 'initial',
                      '&.Mui-selected': {
                        backgroundColor: 'primary.light',
                        color: 'primary.contrastText',
                        '&:hover': {
                          backgroundColor: 'primary.main',
                        },
                        '& .MuiListItemIcon-root': {
                          color: 'primary.contrastText',
                        },
                      },
                    }}
                  >
                    <ListItemIcon
                      sx={{
                        color: isActive ? 'inherit' : 'text.secondary',
                        minWidth: sidebarCollapsed ? 0 : undefined,
                        justifyContent: 'center',
                      }}
                    >
                      {item.icon}
                    </ListItemIcon>
                    <ListItemText
                      primary={item.text}
                      sx={{
                        display: sidebarCollapsed ? 'none' : 'block',
                      }}
                    />
                    {hasSubItems && !sidebarCollapsed && (
                      <IconButton
                        size="small"
                        onClick={(e) => {
                          e.stopPropagation();
                          toggleExpand(item.path);
                        }}
                        sx={{ color: isActive ? 'inherit' : 'text.secondary' }}
                      >
                        {expanded ? <ExpandLess fontSize="small" /> : <ExpandMore fontSize="small" />}
                      </IconButton>
                    )}
                  </ListItemButton>
                </Tooltip>
              </ListItem>
              {hasSubItems && !sidebarCollapsed && (
                <Collapse in={expanded} timeout="auto" unmountOnExit>
                  <List disablePadding>
                    {item.subItems!.map((sub) => {
                      const isSubActive = location.pathname + location.search === sub.path;
                      return (
                        <ListItemButton
                          key={sub.path}
                          onClick={() => handleNavigation(sub.path)}
                          selected={isSubActive}
                          sx={{
                            pl: 4,
                            py: 0.5,
                            '&.Mui-selected': {
                              backgroundColor: 'primary.light',
                              color: 'primary.contrastText',
                              '&:hover': {
                                backgroundColor: 'primary.main',
                              },
                            },
                          }}
                        >
                          <ListItemText
                            primary={sub.text}
                            primaryTypographyProps={{ variant: 'body2' }}
                          />
                        </ListItemButton>
                      );
                    })}
                  </List>
                </Collapse>
              )}
            </Box>
          );
        })}
      </List>
    </Box>
  );

  return (
    <>
      {/* Mobile drawer */}
      <Drawer
        variant="temporary"
        open={mobileOpen}
        onClose={onMobileClose}
        ModalProps={{
          keepMounted: true, // Better mobile performance
        }}
        sx={{
          display: { xs: 'block', sm: 'none' },
          '& .MuiDrawer-paper': {
            boxSizing: 'border-box',
            width: DRAWER_WIDTH,
          },
        }}
        aria-label="Mobile Navigation"
      >
        {drawerContent}
      </Drawer>

      {/* Desktop drawer */}
      <Drawer
        variant="permanent"
        sx={{
          display: { xs: 'none', sm: 'block' },
          width: sidebarCollapsed ? DRAWER_WIDTH_COLLAPSED : DRAWER_WIDTH,
          flexShrink: 0,
          '& .MuiDrawer-paper': {
            width: sidebarCollapsed ? DRAWER_WIDTH_COLLAPSED : DRAWER_WIDTH,
            boxSizing: 'border-box',
            transition: 'width 225ms cubic-bezier(0.4, 0, 0.6, 1)',
            overflowX: 'hidden',
          },
        }}
        open
        aria-label="Desktop Navigation"
      >
        {drawerContent}
      </Drawer>
    </>
  );
}

export default Sidebar;