import {useCallback, useEffect, useState} from 'react';
import {Link} from 'react-router-dom';
import {useTranslation} from 'react-i18next';
import {ChevronLeft, ChevronRight, Link2, Loader2, X} from 'lucide-react';
import {toast} from 'sonner';

import {Badge} from '@/components/ui/badge';
import {Button} from '@/components/ui/button';
import {Card, CardContent, CardHeader, CardTitle} from '@/components/ui/card';
import GameCover from '../components/GameCover.jsx';
import FitText from '../components/FitText.jsx';
import PageContainer from '../components/PageContainer.jsx';
import {dismissPair, fetchLinkQueue, linkGames} from '../utils/links.js';

const PAGE_SIZE = 20;

function PairGame({game}) {
    return (
        <Link to={`/library/${game.appid}`} className="flex min-w-0 flex-1 items-center gap-2 hover:text-primary">
            <GameCover appid={game.appid} imageUrl={game.imageUrl} className="w-16 shrink-0"/>
            <span className="@container min-w-0 flex-1 text-sm font-medium"><FitText text={game.name ?? `App ${game.appid}`}/></span>
        </Link>
    );
}

/**
 * AUDITOR or higher: the pairs IGDB suggests and users asked for. Core checks the role.
 */
export default function LinkQueuePage() {
    const {t} = useTranslation();
    const [page, setPage] = useState(0);
    const [result, setResult] = useState({content: [], totalPages: 0});
    const [status, setStatus] = useState('loading');
    const [busy, setBusy] = useState(false);

    const load = useCallback(async () => {
        try {
            const response = await fetchLinkQueue({page, size: PAGE_SIZE});
            if (response.status === 401) return;
            if (response.status === 403) {
                setStatus('forbidden');
                return;
            }
            if (!response.ok) {
                setStatus('error');
                return;
            }
            const data = await response.json();
            // The last pair of the last page was decided: show the page before.
            if (data.content.length === 0 && page > 0) {
                setPage(page - 1);
                return;
            }
            setResult(data);
            setStatus('ready');
        } catch (err) {
            console.error('Link queue error:', err);
            setStatus('error');
        }
    }, [page]);

    useEffect(() => {
        load();
    }, [load]);

    const run = async (request, doneKey) => {
        setBusy(true);
        try {
            const response = await request();
            if (response.status === 401) return;
            if (response.ok) {
                toast.success(t(doneKey));
            } else {
                const data = await response.json().catch(() => ({}));
                toast.error(t(data.code === 'ALREADY_LINKED' ? 'LINKS.ERROR_CODES.ALREADY_LINKED' : 'LINKS.ERROR'));
            }
            await load();
        } catch (err) {
            console.error('Link queue action error:', err);
            toast.error(t('INFO.ERROR.NETWORK_FAILURE'));
        } finally {
            setBusy(false);
        }
    };

    if (status === 'forbidden') {
        return (
            <PageContainer className="px-4 py-6 md:px-8">
                <p className="text-sm text-muted-foreground">{t('LINKS.NO_ACCESS')}</p>
            </PageContainer>
        );
    }

    return (
        <PageContainer className="space-y-4 px-4 py-6 md:px-8">
            <Card>
                <CardHeader>
                    <CardTitle>{t('LINKS.QUEUE_TITLE')}</CardTitle>
                </CardHeader>
                <CardContent>
                    {status === 'loading' && <Loader2 className="size-5 animate-spin text-muted-foreground"/>}
                    {status === 'error' && <p className="text-sm text-destructive">{t('LINKS.ERROR')}</p>}
                    {status === 'ready' && result.content.length === 0 && (
                        <p className="text-sm text-muted-foreground">{t('LINKS.QUEUE_EMPTY')}</p>
                    )}
                    {status === 'ready' && result.content.length > 0 && (
                        <ul className="divide-y">
                            {result.content.map(({a, b, igdb, requests}) => (
                                <li key={`${a.appid}-${b.appid}`} className="flex flex-wrap items-center gap-3 py-3">
                                    <div className="flex min-w-0 flex-1 flex-wrap items-center gap-3">
                                        <PairGame game={a}/>
                                        <PairGame game={b}/>
                                    </div>
                                    {igdb && <Badge variant="secondary">{t('LINKS.FROM_IGDB')}</Badge>}
                                    {requests > 0 && <Badge variant="outline">{t('LINKS.REQUESTED_BY', {count: requests})}</Badge>}
                                    <Button type="button" size="sm" disabled={busy}
                                            onClick={() => run(() => linkGames(a.appid, b.appid), 'LINKS.LINKED')}>
                                        <Link2/>{t('LINKS.LINK')}
                                    </Button>
                                    <Button type="button" variant="outline" size="sm" disabled={busy}
                                            onClick={() => run(() => dismissPair(a.appid, b.appid), 'LINKS.DISMISSED')}>
                                        <X/>{t('LINKS.DISMISS')}
                                    </Button>
                                </li>
                            ))}
                        </ul>
                    )}
                    {status === 'ready' && result.totalPages > 1 && (
                        <div className="flex items-center justify-between gap-2 pt-3 text-sm">
                            <Button type="button" variant="outline" size="sm" disabled={page === 0}
                                    onClick={() => setPage(page - 1)}>
                                <ChevronLeft/>{t('ADMIN.PREVIOUS')}
                            </Button>
                            <span>{t('LINKS.PAGE_OF', {current: page + 1, total: result.totalPages})}</span>
                            <Button type="button" variant="outline" size="sm" disabled={page + 1 >= result.totalPages}
                                    onClick={() => setPage(page + 1)}>
                                {t('ADMIN.NEXT')}<ChevronRight/>
                            </Button>
                        </div>
                    )}
                </CardContent>
            </Card>
        </PageContainer>
    );
}