import {useEffect, useState} from 'react';
import {Link, NavLink, useLocation, useNavigate} from 'react-router-dom';
import {useTranslation} from 'react-i18next';
import {Bell, ChartColumn, CircleQuestionMark, Coins, Dices, Eye, Languages, LayoutDashboard, Library, Link2, LogOut, Mail, Megaphone, Moon, Newspaper, ScrollText, Search, Settings, Shield, Sun, Users} from 'lucide-react';
import {toast} from 'sonner';

import {Badge} from '@/components/ui/badge';
import {Button} from '@/components/ui/button';
import {
    DropdownMenu,
    DropdownMenuContent,
    DropdownMenuItem,
    DropdownMenuSeparator,
    DropdownMenuSub,
    DropdownMenuSubContent,
    DropdownMenuSubTrigger,
    DropdownMenuTrigger,
} from '@/components/ui/dropdown-menu';
import {usePreferences} from '@/context/PreferencesContext.jsx';
import {cn} from '@/lib/utils';
import Logo from './Logo.jsx';
import PageContainer from './PageContainer.jsx';
import SteamAvatar from './SteamAvatar.jsx';
import useCurrentUser from '../hooks/useCurrentUser.js';
import useSteamProfile from '../hooks/useSteamProfile.js';
import {fetchPendingCount, ROLES, viewAs} from '../utils/admin.js';
import {canCorrect} from '../utils/corrections.js';
import {fetchInbox} from '../utils/inbox.js';
import {fetchQuestionCount} from '../utils/questions.js';
import {expireSession, markSession} from '../utils/auth.js';

const NAV_ITEMS = [
    {to: '/dashboard', labelKey: 'NAV.DASHBOARD', Icon: LayoutDashboard},
    // The wishlist and the backlog order are tabs of the library.
    {to: '/library', labelKey: 'NAV.LIBRARY', Icon: Library, alsoActiveOn: ['/wishlist', '/backlog']},
    {to: '/play-next', labelKey: 'NAV.PLAY_NEXT', Icon: Dices},
    {to: '/questions', labelKey: 'NAV.QUESTIONS', Icon: CircleQuestionMark},
    {to: '/stats', labelKey: 'NAV.STATS', Icon: ChartColumn},
    {to: '/', labelKey: 'NAV.COMMUNITY', Icon: Users, iconOnly: true},
];

const CountBadge = ({count}) => (
    <span aria-hidden="true"
          className="absolute -top-1 -right-1 flex size-4 items-center justify-center rounded-full bg-primary text-[10px] font-bold text-primary-foreground">
        {count > 9 ? '9+' : count}
    </span>
);

const navLinkClass = (isActive) => cn(
    'flex items-center gap-2 rounded-lg px-1 py-2 text-sm font-medium transition-colors sm:px-3',
    isActive
        ? 'bg-accent text-accent-foreground'
        : 'text-muted-foreground hover:bg-muted hover:text-foreground',
);

export default function AppHeader({isAuthenticated, onLogout}) {
    const {t, i18n} = useTranslation();
    const {isDarkMode, setDarkMode, setLanguage, wallet} = usePreferences();
    const {pathname} = useLocation();
    const steamProfile = useSteamProfile(isAuthenticated);
    const currentUser = useCurrentUser(isAuthenticated);
    const navigate = useNavigate();
    const isAdmin = currentUser?.role === 'PLATFORM_ADMIN';
    const viewingAs = currentUser && currentUser.activeRole !== currentUser.role ? currentUser.activeRole : null;
    const seesAdminPage = isAdmin && !viewingAs;
    const [pendingCount, setPendingCount] = useState(0);
    const [menuOpenings, setMenuOpenings] = useState(0);

    // Loaded again on every page change and menu opening, so a decision on the admin page shows soon.
    useEffect(() => {
        if (!seesAdminPage) return undefined;
        let current = true;
        fetchPendingCount()
            .then(async (response) => {
                if (current && response.ok) setPendingCount((await response.json()).count);
            })
            .catch((err) => console.error('Pending count error:', err));
        return () => {
            current = false;
        };
    }, [seesAdminPage, pathname, menuOpenings]);
    const shownCount = seesAdminPage ? pendingCount : 0;

    // Loaded again on every page change. The inbox page marks the notes read, so it shows no count.
    const [unread, setUnread] = useState(0);
    useEffect(() => {
        if (!isAuthenticated) return undefined;
        let current = true;
        fetchInbox().then(({ok, data}) => {
            if (current && ok) setUnread(data.unread);
        });
        return () => {
            current = false;
        };
    }, [isAuthenticated, pathname]);
    const shownUnread = pathname === '/inbox' ? 0 : unread;

    // Loaded again on every page change. The questions page shows the live count in its title, so it has no badge.
    const [openQuestions, setOpenQuestions] = useState(0);
    useEffect(() => {
        if (!isAuthenticated) return undefined;
        let current = true;
        fetchQuestionCount().then(({ok, data}) => {
            if (current && ok) setOpenQuestions(data.count);
        });
        return () => {
            current = false;
        };
    }, [isAuthenticated, pathname]);
    const shownQuestions = pathname === '/questions' ? 0 : openQuestions;
    // Below sm the Questions icon shows only with open questions or on its own page; the points chip then gives up its number.
    const questionsIconHidden = openQuestions === 0 && pathname !== '/questions';

    const switchRole = async (role) => {
        try {
            const response = await viewAs(role === currentUser.role ? null : role);
            if (response.ok) {
                // New cookies with the other role; the new stamp loads the user and the Steam data again.
                markSession();
                navigate('/dashboard');
                return;
            }
            if (response.status === 401) {
                expireSession();
                return;
            }
        } catch (err) {
            console.error('View as error:', err);
        }
        toast.error(t('NAV.VIEW_AS.ERROR'));
    };

    // Unsaved, the next login would switch back to Auth's language.
    const toggleLanguage = async () => {
        try {
            const response = await setLanguage(i18n.language === 'de' ? 'en' : 'de');
            if (response && !response.ok) toast.error(t('SETTINGS.ERROR_SAVE'));
        } catch (err) {
            console.error('Language save error:', err);
            toast.error(t('INFO.ERROR.NETWORK_FAILURE'));
        }
    };
    const toggleTheme = () => setDarkMode(!isDarkMode);
    const ThemeIcon = isDarkMode ? Sun : Moon;

    return (
        <header className="sticky top-0 z-50 border-b bg-background/80 backdrop-blur supports-[backdrop-filter]:bg-background/60">
            <PageContainer className="flex h-16 items-center gap-1 px-4 sm:gap-2 md:px-8">
                <Link to={isAuthenticated ? '/dashboard' : '/'} aria-label="ToBePlayed" className="flex items-center gap-2 font-bold tracking-tight sm:mr-2 whitespace-nowrap">
                    <Logo className="h-8 w-auto shrink-0"/>
                    {/* On a narrow phone the menu and buttons need the room; the logo alone stays. */}
                    <span className="hidden text-lg min-[520px]:inline">ToBePlayed</span>
                </Link>

                {isAuthenticated && (
                    <nav className="flex items-center sm:gap-1">
                        {NAV_ITEMS.map(({to, labelKey, Icon, alsoActiveOn = [], iconOnly}) => {
                            const count = to === '/questions' ? shownQuestions : 0;
                            return (
                                <NavLink key={to} to={to} title={t(labelKey)}
                                         aria-label={count > 0 ? t(`${labelKey}_OPEN`, {count}) : undefined}
                                         className={({isActive}) => cn(navLinkClass(isActive || alsoActiveOn.includes(pathname)), 'relative',
                                         to === '/questions' && questionsIconHidden && 'max-sm:hidden')}>
                                    <Icon className="size-4"/>
                                    {!iconOnly && <span className="hidden lg:inline">{t(labelKey)}</span>}
                                    {count > 0 && <CountBadge count={count}/>}
                                </NavLink>
                            );
                        })}
                    </nav>
                )}

                <div className="ml-auto flex min-w-0 items-center gap-1">
                    {/* The badge hangs on the header's bottom edge at every width: in the row it would push the page sideways. */}
                    {isAuthenticated && viewingAs && (
                        <Badge variant="secondary" className="absolute top-full left-1/2 -translate-x-1/2 -translate-y-1/2 pointer-events-none border-border">{t('NAV.VIEW_AS.BADGE', {role: t(`ROLES.${viewingAs}`)})}</Badge>
                    )}
                    {isAuthenticated && wallet && (
                        <Button asChild variant="ghost" size="sm" title={`${t('POINTS.TITLE')}: ${wallet.balance}`} className="min-w-0 shrink lg:shrink-0">
                            <Link to="/points" aria-label={`${t('POINTS.TITLE')}: ${wallet.balance}`}>
                                <Coins className="text-primary"/>
                                <span className={cn('min-w-0 truncate tabular-nums', !questionsIconHidden && 'max-sm:hidden')}>{wallet.balance}</span>
                            </Link>
                        </Button>
                    )}
                    {isAuthenticated && (
                        <Button asChild variant="ghost" size="icon" title={t('NAV.INBOX')} className="relative shrink-0">
                            <Link to="/inbox" aria-label={shownUnread > 0 ? t('NAV.INBOX_UNREAD', {count: shownUnread}) : t('NAV.INBOX')}>
                                <Bell/>
                                {shownUnread > 0 && <CountBadge count={shownUnread}/>}
                            </Link>
                        </Button>
                    )}
                    {isAuthenticated ? (
                        <DropdownMenu onOpenChange={(open) => open && setMenuOpenings((count) => count + 1)}>
                            <DropdownMenuTrigger asChild>
                                <Button variant="ghost" size="icon" aria-label={t('NAV.MENU')} title={steamProfile?.personaName ?? undefined}
                                        className="relative">
                                    <SteamAvatar url={steamProfile?.avatarUrl}/>
                                    {shownCount > 0 && (
                                        <span aria-label={t('NAV.PENDING_REQUESTS', {count: shownCount})}
                                              className="absolute -top-1 -right-1 flex size-4 items-center justify-center rounded-full bg-primary text-[10px] font-bold text-primary-foreground">
                                            {shownCount > 9 ? '9+' : shownCount}
                                        </span>
                                    )}
                                </Button>
                            </DropdownMenuTrigger>
                            <DropdownMenuContent align="end" className="w-52">
                                <DropdownMenuItem asChild>
                                    <Link to="/settings"><Settings/>{t('NAV.SETTINGS')}</Link>
                                </DropdownMenuItem>
                                <DropdownMenuItem asChild>
                                    <Link to="/points"><Coins/>{t('NAV.POINTS')}</Link>
                                </DropdownMenuItem>
                                <DropdownMenuItem asChild>
                                    <Link to="/inbox"><Bell/>{t('NAV.INBOX')}</Link>
                                </DropdownMenuItem>
                                <DropdownMenuItem asChild>
                                    <Link to="/whats-new"><Newspaper/>{t('NAV.WHATS_NEW')}</Link>
                                </DropdownMenuItem>
                                {canCorrect(currentUser) && (
                                    <>
                                        <DropdownMenuItem asChild>
                                            <Link to="/audit/games"><Search/>{t('NAV.GAME_CATALOG')}</Link>
                                        </DropdownMenuItem>
                                        <DropdownMenuItem asChild>
                                            <Link to="/audit/links"><Link2/>{t('NAV.LINK_QUEUE')}</Link>
                                        </DropdownMenuItem>
                                        <DropdownMenuItem asChild>
                                            <Link to="/audit/log"><ScrollText/>{t('NAV.AUDIT_LOG')}</Link>
                                        </DropdownMenuItem>
                                    </>
                                )}
                                {seesAdminPage && (
                                    <>
                                        <DropdownMenuItem asChild>
                                            <Link to="/admin/users">
                                                <Shield/>{t('NAV.ADMIN')}
                                                {shownCount > 0 && <Badge className="ml-auto">{shownCount}</Badge>}
                                            </Link>
                                        </DropdownMenuItem>
                                        <DropdownMenuItem asChild>
                                            <Link to="/admin/hints"><Megaphone/>{t('NAV.ADMIN_HINTS')}</Link>
                                        </DropdownMenuItem>
                                        <DropdownMenuItem asChild>
                                            <Link to="/admin/news"><Newspaper/>{t('NAV.ADMIN_NEWS')}</Link>
                                        </DropdownMenuItem>
                                        <DropdownMenuItem asChild>
                                            <Link to="/admin/broadcasts"><Mail/>{t('NAV.ADMIN_BROADCASTS')}</Link>
                                        </DropdownMenuItem>
                                    </>
                                )}
                                {isAdmin && (
                                    <DropdownMenuSub>
                                        <DropdownMenuSubTrigger><Eye/>{t('NAV.VIEW_AS.MENU')}</DropdownMenuSubTrigger>
                                        <DropdownMenuSubContent>
                                            {ROLES.map((role) => (
                                                <DropdownMenuItem key={role} disabled={role === currentUser.activeRole}
                                                                  onSelect={() => switchRole(role)}>
                                                    {t(`ROLES.${role}`)}
                                                </DropdownMenuItem>
                                            ))}
                                        </DropdownMenuSubContent>
                                    </DropdownMenuSub>
                                )}
                                <DropdownMenuItem onSelect={toggleLanguage}>
                                    <Languages/>{t('NAV.LANGUAGE')}: {i18n.language.toUpperCase()}
                                </DropdownMenuItem>
                                <DropdownMenuItem onSelect={toggleTheme}>
                                    <ThemeIcon/>{t(isDarkMode ? 'NAV.LIGHT_MODE' : 'NAV.DARK_MODE')}
                                </DropdownMenuItem>
                                <DropdownMenuSeparator/>
                                <DropdownMenuItem variant="destructive" onSelect={onLogout}>
                                    <LogOut/>{t('MAIN.LOGOUT')}
                                </DropdownMenuItem>
                            </DropdownMenuContent>
                        </DropdownMenu>
                    ) : (
                        <>
                            <Button variant="ghost" size="sm" onClick={toggleLanguage}>
                                {i18n.language.toUpperCase()}
                            </Button>
                            <Button variant="ghost" size="icon" onClick={toggleTheme} aria-label={t(isDarkMode ? 'NAV.LIGHT_MODE' : 'NAV.DARK_MODE')}>
                                <ThemeIcon className="size-5"/>
                            </Button>
                            <Button asChild className="ml-1">
                                <Link to="/login">{t('MAIN.LOGIN')}</Link>
                            </Button>
                        </>
                    )}
                </div>
            </PageContainer>
        </header>
    );
}