import {useEffect, useMemo, useState} from 'react';
import {Link, useNavigate, useParams} from 'react-router-dom';
import {useTranslation} from 'react-i18next';
import {ArrowLeft, Clock, ExternalLink, ShieldOff, Trophy} from 'lucide-react';

import {Badge} from '@/components/ui/badge';
import {Button} from '@/components/ui/button';
import {Card} from '@/components/ui/card';
import {Skeleton} from '@/components/ui/skeleton';
import {cn} from '@/lib/utils';
import BacklogCard from '../components/BacklogCard.jsx';
import GameCover from '../components/GameCover.jsx';
import GameStatusBadge from '../components/GameStatusBadge.jsx';
import {formatPlaytime} from '../utils/games.js';

const formatUnlockedAt = (instant, locale) => {
    if (!instant) return '';
    try {
        return new Date(instant).toLocaleDateString(locale, {year: 'numeric', month: 'short', day: 'numeric'});
    } catch {
        return '';
    }
};

export default function GameDetail() {
    const {t, i18n} = useTranslation();
    const {appid} = useParams();
    const navigate = useNavigate();

    const [data, setData] = useState(null);
    const [isLoading, setIsLoading] = useState(true);
    const [error, setError] = useState(null);

    useEffect(() => {
        let cancelled = false;
        const token = localStorage.getItem('tbp_jwt');
        if (!token) {
            navigate('/login');
            return;
        }
        setIsLoading(true);
        setError(null);
        (async () => {
            try {
                const url = `${import.meta.env.VITE_CORE_API_URL}/api/library/games/${appid}`;
                const response = await fetch(url, {
                    headers: {
                        'Authorization': `Bearer ${token}`,
                        'Content-Type': 'application/json',
                    },
                });
                if (cancelled) return;
                if (response.status === 401) {
                    localStorage.removeItem('tbp_jwt');
                    navigate('/login');
                    return;
                }
                if (response.status === 404) {
                    setError(t('GAME_DETAIL.NOT_FOUND'));
                    return;
                }
                if (!response.ok) {
                    setError(t('GAME_DETAIL.ERROR_LOAD'));
                    return;
                }
                const json = await response.json();
                setData(json);
            } catch (err) {
                if (!cancelled) {
                    console.error('GameDetail load error:', err);
                    setError(t('INFO.ERROR.NETWORK_FAILURE'));
                }
            } finally {
                if (!cancelled) setIsLoading(false);
            }
        })();
        return () => {
            cancelled = true;
        };
    }, [appid, navigate, t]);

    const sortedAchievements = useMemo(() => {
        if (!data?.achievements) return [];
        return [...data.achievements].sort((a, b) => {
            if (a.unlocked !== b.unlocked) return a.unlocked ? -1 : 1;
            if (a.unlocked && b.unlocked) {
                return (b.unlockedAt ?? '').localeCompare(a.unlockedAt ?? '');
            }
            return (a.displayName ?? a.apiName).localeCompare(b.displayName ?? b.apiName);
        });
    }, [data]);

    const stats = data ? [
        [t('GAME_DETAIL.UNLOCKED'), data.achievementsUnlocked],
        [t('GAME_DETAIL.REMAINING'), data.achievementsRemaining],
        [t('GAME_DETAIL.COMPLETION'), `${data.completionPercent}%`],
    ] : [];

    return (
        <div className="w-full max-w-5xl mx-auto p-4 md:p-8 space-y-6">
            <Button variant="ghost" size="sm" className="-ml-2" onClick={() => navigate(-1)}>
                <ArrowLeft/>{t('GAME_DETAIL.BACK')}
            </Button>

            {isLoading && (
                <div className="space-y-6">
                    <Skeleton className="h-52 rounded-xl"/>
                    <Skeleton className="h-40 rounded-xl"/>
                </div>
            )}

            {error && !isLoading && (
                <div className="py-12 text-center text-destructive space-y-4">
                    <p>{error}</p>
                    <Button asChild variant="outline"><Link to="/library">{t('GAME_DETAIL.BACK_TO_LIBRARY')}</Link></Button>
                </div>
            )}

            {!isLoading && !error && data && (
                <>
                    <Card className="relative overflow-hidden p-0 gap-0 md:flex-row">
                        <GameCover appid={data.appid} className="w-full rounded-none md:w-96 md:shrink-0"/>
                        <div className="flex flex-1 flex-col justify-between gap-4 p-6">
                            <div>
                                <h1 className="text-2xl md:text-3xl font-bold tracking-tight">
                                    {data.name ?? `App ${data.appid}`}
                                </h1>
                                <div className="mt-3 flex flex-wrap gap-2">
                                    <Badge variant="secondary" className="tabular-nums">
                                        <Clock className="size-3"/>
                                        {t('GAME_DETAIL.PLAYTIME', {time: formatPlaytime(data.playtimeMinutes)})}
                                    </Badge>
                                    <GameStatusBadge status={data.status}/>
                                </div>
                            </div>
                            <Button asChild variant="outline" size="sm" className="self-start">
                                <a href={`https://store.steampowered.com/app/${data.appid}`} target="_blank" rel="noopener noreferrer">
                                    {t('GAME_DETAIL.OPEN_IN_STEAM')}<ExternalLink/>
                                </a>
                            </Button>
                        </div>
                    </Card>

                    <BacklogCard key={data.appid} game={data} onSaved={(entry) => setData((d) => ({...d, ...entry}))}/>

                    {!data.hasAchievements && (
                        <Card className="items-center py-10 text-center text-sm text-muted-foreground">
                            <Trophy className="size-8"/>
                            {t('GAME_DETAIL.NO_ACHIEVEMENTS')}
                        </Card>
                    )}

                    {data.hasAchievements && !data.statsVisible && (
                        <Card className="items-center py-10 text-center text-sm text-muted-foreground">
                            <ShieldOff className="size-8"/>
                            {t('GAME_DETAIL.STATS_HIDDEN')}
                        </Card>
                    )}

                    {data.hasAchievements && data.statsVisible && (
                        <>
                            <Card className="p-6 gap-5">
                                <div className="flex items-baseline justify-between">
                                    <h2 className="flex items-center gap-2 text-lg font-semibold">
                                        <Trophy className="size-4 text-amber-500"/>
                                        {t('GAME_DETAIL.ACHIEVEMENTS')}
                                    </h2>
                                    <span className="text-sm text-muted-foreground tabular-nums">
                                        {data.achievementsUnlocked} / {data.achievementsTotal}
                                    </span>
                                </div>
                                <div className="h-2.5 w-full overflow-hidden rounded-full bg-muted">
                                    <div
                                        className="h-full rounded-full bg-primary transition-all"
                                        style={{width: `${Math.min(100, data.completionPercent)}%`}}
                                    />
                                </div>
                                <div className="grid grid-cols-3 gap-3 text-center">
                                    {stats.map(([label, value]) => (
                                        <div key={label} className="rounded-lg bg-muted/50 p-3">
                                            <div className="text-2xl font-bold tabular-nums">{value}</div>
                                            <div className="text-xs text-muted-foreground">{label}</div>
                                        </div>
                                    ))}
                                </div>
                            </Card>

                            <ul className="grid grid-cols-1 sm:grid-cols-2 gap-3">
                                {sortedAchievements.map((a) => {
                                    const icon = a.unlocked ? a.iconUrl : a.iconGrayUrl;
                                    return (
                                        <li
                                            key={a.apiName}
                                            className={cn(
                                                'flex items-start gap-3 rounded-xl border bg-card p-3',
                                                a.unlocked ? 'border-primary/40' : 'opacity-60',
                                            )}
                                        >
                                            {icon
                                                ? <img src={icon} alt="" className={cn('size-12 rounded-md', !a.unlocked && 'grayscale')}/>
                                                : <div className="size-12 rounded-md bg-muted"/>}
                                            <div className="min-w-0 flex-1">
                                                <div className="truncate font-medium">{a.displayName ?? a.apiName}</div>
                                                {a.description && (
                                                    <div className="mt-1 line-clamp-2 text-xs text-muted-foreground">{a.description}</div>
                                                )}
                                                {a.unlocked && a.unlockedAt && (
                                                    <div className="mt-1 text-xs text-primary tabular-nums">
                                                        {formatUnlockedAt(a.unlockedAt, i18n.language)}
                                                    </div>
                                                )}
                                            </div>
                                        </li>
                                    );
                                })}
                            </ul>
                        </>
                    )}
                </>
            )}
        </div>
    );
}