import {
	AppBar,
	Box,
	Button,
	Divider,
	Drawer,
	IconButton,
	List,
	ListItemButton,
	ListItemIcon,
	ListItemText,
	Toolbar,
	Tooltip,
	Typography,
	useMediaQuery,
	useTheme,
} from '@mui/material';
import AdminPanelSettingsOutlinedIcon from '@mui/icons-material/AdminPanelSettingsOutlined';
import CircleOutlinedIcon from '@mui/icons-material/CircleOutlined';
import Inventory2OutlinedIcon from '@mui/icons-material/Inventory2Outlined';
import DashboardOutlinedIcon from '@mui/icons-material/DashboardOutlined';
import MenuIcon from '@mui/icons-material/Menu';
import LogoutIcon from '@mui/icons-material/Logout';
import PeopleOutlinedIcon from '@mui/icons-material/PeopleOutlined';
import SecurityOutlinedIcon from '@mui/icons-material/SecurityOutlined';
import TuneOutlinedIcon from '@mui/icons-material/TuneOutlined';
import { useEffect, useState } from 'react';
import { useLocation } from 'react-router-dom';
import { getNavigation } from '../../api/client';
import NotificationMenu from '../notifications/NotificationMenu';

const DRAWER_WIDTH = 224;
const DEFAULT_HEADER_LABEL = 'Workspace';
const NAVIGATION_ICONS = {
	Demo: DashboardOutlinedIcon,
	Admin: AdminPanelSettingsOutlinedIcon,
	Roles: SecurityOutlinedIcon,
	'PHPEngine Settings': TuneOutlinedIcon,
	Users: PeopleOutlinedIcon,
	'Inventory Monitor': Inventory2OutlinedIcon,
};

/**
 * Converts a menu URL into an internal React route.
 *
 * @param {string} url Legacy menu URL.
 * @returns {string} Route path.
 * @sideEffects None.
 */
function toRoute(url) {
	return url.startsWith('/') ? url : `/${url}`;
}

/**
 * Splits the flat, legacy menu payload into root links and populated groups.
 *
 * @param {Array<Record<string, unknown>>} navigation Authorized navigation entries.
 * @returns {{topLevelItems: Array<Record<string, unknown>>, groups: Array<Record<string, unknown>>}} Display-ready navigation structure.
 * @sideEffects None.
 */
function getNavigationStructure(navigation) {
	const groups = navigation
		.filter(item => item.mainMenu && !item.url)
		.map(group => ({
			...group,
			items: navigation.filter(item => item.mainMenu === group.name && item.url),
		}))
		.filter(group => group.items.length > 0);

	return {
		topLevelItems: navigation.filter(item => !item.mainMenu && item.url),
		groups,
	};
}

/**
 * Renders one compact navigation entry with its selected and disabled states.
 *
 * @param {{item: Record<string, unknown>, selected: boolean, onClick: () => void}} props Navigation entry properties.
 * @returns {JSX.Element} Navigation button.
 * @sideEffects None.
 */
function NavigationItem({ item, selected, onClick }) {
	const Icon = NAVIGATION_ICONS[item.name] ?? CircleOutlinedIcon;

	return (
		<ListItemButton
			selected={selected}
			disabled={item.isDisabled}
			onClick={onClick}
			sx={{
				minHeight: 42,
				mb: 0.5,
				borderLeft: '3px solid',
				borderColor: selected ? 'primary.main' : 'transparent',
				borderRadius: 1,
				color: selected ? 'navigation.contrastText' : 'navigation.muted',
				pl: 1.5,
				'&:hover': {
					backgroundColor: 'navigation.hover',
					color: 'navigation.contrastText',
				},
				'&.Mui-selected': {
					backgroundColor: 'navigation.active',
				},
				'&.Mui-selected:hover': {
					backgroundColor: 'navigation.active',
				},
				'&.Mui-focusVisible': {
					outline: '2px solid',
					outlineColor: 'primary.light',
					outlineOffset: -2,
				},
			}}
		>
			<ListItemIcon sx={{ minWidth: 34, color: 'inherit' }}>
				<Icon fontSize="small" />
			</ListItemIcon>
			<ListItemText
				primary={item.name}
				primaryTypographyProps={{ fontSize: '0.875rem', fontWeight: selected ? 700 : 500 }}
			/>
		</ListItemButton>
	);
}

/**
 * Renders the authenticated responsive application shell.
 *
 * @param {{session: Record<string, unknown>, onNavigate: (path: string) => void, onLogout: () => void, children: import('react').ReactNode}} props Shell properties.
 * @returns {JSX.Element} Application shell.
 * @sideEffects Loads permission-filtered navigation and renders authenticated controls.
 */
function AppShell({ session, onNavigate, onLogout, children }) {
	const theme = useTheme();
	const location = useLocation();
	const isMobile = useMediaQuery(theme.breakpoints.down('md'));
	const [mobileOpen, setMobileOpen] = useState(false);
	const [navigation, setNavigation] = useState([]);
	const [navigationError, setNavigationError] = useState('');
	const { topLevelItems, groups } = getNavigationStructure(navigation);
	const activeItem = navigation.find(item => item.url && toRoute(item.url) === location.pathname);
	const activeGroup = groups.find(group =>
		group.items.some(item => toRoute(item.url) === location.pathname),
	);
	const headerLabel = activeGroup?.name ?? DEFAULT_HEADER_LABEL;

	useEffect(() => {
		let isMounted = true;

		getNavigation()
			.then(items => {
				if (isMounted) {
					setNavigation(items);
				}
			})
			.catch(() => {
				if (isMounted) {
					setNavigationError('Navigation is temporarily unavailable.');
				}
			});

		return () => {
			isMounted = false;
		};
	}, [session]);

	/**
	 * Navigates through the route controller and closes a mobile drawer.
	 *
	 * @param {string} url Authorized menu URL.
	 * @returns {void}
	 * @sideEffects Changes the application route through the parent controller.
	 */
	function handleNavigation(url) {
		setMobileOpen(false);
		onNavigate(toRoute(url));
	}

	const drawer = (
		<Box
			role="presentation"
			sx={{
				display: 'flex',
				minHeight: '100%',
				flexDirection: 'column',
				backgroundColor: 'navigation.main',
			}}
		>
			<Box sx={{ display: 'flex', alignItems: 'center', gap: 1.25, px: 2, py: 2.25 }}>
				<Box
					aria-hidden="true"
					sx={{
						display: 'grid',
						height: 32,
						width: 32,
						placeItems: 'center',
						borderRadius: 1,
						backgroundColor: 'primary.main',
						color: 'primary.contrastText',
						fontSize: '0.75rem',
						fontWeight: 800,
						letterSpacing: '-0.06em',
					}}
				>
					PHP
				</Box>
				<Box>
					<Typography sx={{ color: 'navigation.contrastText', fontSize: '0.9375rem', fontWeight: 700 }}>
						PHPEngine
					</Typography>
					<Typography variant="overline" sx={{ color: 'navigation.muted', display: 'block', lineHeight: 1.3 }}>
						Console
					</Typography>
				</Box>
			</Box>
			<Divider sx={{ borderColor: 'navigation.divider' }} />
			<List component="nav" aria-label="Application navigation" disablePadding sx={{ px: 1.25, py: 1.5 }}>
				{topLevelItems.map(item => (
					<NavigationItem
						key={item.name}
						item={item}
						selected={toRoute(item.url) === location.pathname}
						onClick={() => handleNavigation(item.url)}
					/>
				))}
				{groups.map(group => (
					<Box key={group.name} sx={{ mt: 2.25 }}>
						<Typography
							variant="overline"
							sx={{ color: 'navigation.muted', display: 'block', px: 1.5, pb: 0.75 }}
						>
							{group.name}
						</Typography>
						{group.items.map(item => (
							<NavigationItem
								key={item.name}
								item={item}
								selected={toRoute(item.url) === location.pathname}
								onClick={() => handleNavigation(item.url)}
							/>
						))}
					</Box>
				))}
				{navigationError && (
					<Typography sx={{ color: '#fca5a5', px: 1.5, py: 2, fontSize: '0.75rem' }}>
						{navigationError}
					</Typography>
				)}
			</List>
		</Box>
	);

	return (
		<Box className="flex min-h-screen bg-slate-100">
			<AppBar
				position="fixed"
				color="inherit"
				elevation={0}
				className="border-b border-slate-200"
				sx={{
					ml: { md: `${DRAWER_WIDTH}px` },
					width: { md: `calc(100% - ${DRAWER_WIDTH}px)` },
				}}
			>
				<Toolbar className="gap-2" sx={{ pt: 'env(safe-area-inset-top, 0px)' }}>
					{isMobile && (
						<IconButton color="inherit" aria-label="Open navigation" onClick={() => setMobileOpen(true)}>
							<MenuIcon />
						</IconButton>
					)}
					<Box sx={{ flex: 1, minWidth: 0 }}>
						<Typography
							variant="overline"
							sx={{ color: 'text.secondary', display: { xs: 'none', md: 'block' }, lineHeight: 1.3 }}
						>
							{headerLabel}
						</Typography>
						<Typography variant="h6" component="div" noWrap>
							{isMobile ? 'PHPEngine' : activeItem?.name ?? 'PHPEngine'}
						</Typography>
					</Box>
					<NotificationMenu onNavigate={onNavigate} />
					<Tooltip title="Sign out">
						<Button color="inherit" startIcon={<LogoutIcon />} onClick={onLogout}>
							<span className="hidden sm:inline">Sign out</span>
						</Button>
					</Tooltip>
				</Toolbar>
			</AppBar>
			{isMobile ? (
				<Drawer open={mobileOpen} onClose={() => setMobileOpen(false)} PaperProps={{ sx: { width: DRAWER_WIDTH } }}>
					{drawer}
				</Drawer>
			) : (
				<Box component="aside" sx={{ display: { xs: 'none', md: 'block' }, flexShrink: 0, width: DRAWER_WIDTH }}>
					<Drawer variant="permanent" PaperProps={{ sx: { width: DRAWER_WIDTH } }}>
						{drawer}
					</Drawer>
				</Box>
			)}
			<Box component="main" className="min-w-0 flex-1 px-4 pb-8 pt-24 sm:px-8">
				{children}
			</Box>
		</Box>
	);
}

export default AppShell;