import { useEffect, useState } from 'react';
import { apiGet } from '../api.js';
import { SkeletonRows } from '../components/Skeleton.jsx';
import { IconTrophy, IconLevel } from '../icons.jsx';
import EmptyState from '../components/EmptyState.jsx';
import { useT, useFmt } from '../i18n.jsx';

/** Muss der Formel in src/bot/levels.js entsprechen */
function xpForLevel(level) {
    let total = 0;
    for (let n = 0; n < level; n++) total += 5 * n * n + 50 * n + 100;
    return total;
}

// Platz 1–3 bekommen einen Pokal in Gold/Silber/Bronze, danach schlicht die Nummer
const MEDAL_COLORS = ['#f5c518', '#c0c4cc', '#c07a3e'];

/** Nachrichten/Tag der letzten 30 Tage als Balken */
function ActivityChart({ stats }) {
    const { t } = useT();
    const { zahl } = useFmt();
    const byDay = new Map(stats.days.map((d) => [d.day, d]));
    const days = [];
    for (let i = 29; i >= 0; i--) {
        const key = new Date(Date.now() - i * 86400000).toISOString().slice(0, 10);
        days.push({ key, ...(byDay.get(key) ?? { messages: 0, joins: 0, leaves: 0 }) });
    }
    const max = Math.max(1, ...days.map((d) => d.messages));
    const total = days.reduce((s, d) => s + d.messages, 0);
    return (
        <div className="roadmap-group" style={{ marginTop: '2.5rem' }}>
            <h2 className="settings-title">{t('level.activity', zahl(total), stats.members)}</h2>
            <div className="act-chart">
                {days.map((d) => (
                    <span
                        key={d.key}
                        className="act-bar"
                        style={{ height: `${Math.max(4, (d.messages / max) * 100)}%` }}
                        title={t('level.barTitle', d.key, d.messages, d.joins, d.leaves)}
                    />
                ))}
            </div>
        </div>
    );
}

export default function Level() {
    const { t } = useT();
    const { zahl } = useFmt();
    const [rows, setRows] = useState(null);
    const [stats, setStats] = useState(null);
    const [error, setError] = useState(false);

    useEffect(() => {
        apiGet('/api/levels').then((d) => setRows(d.levels)).catch(() => setError(true));
        apiGet('/api/serverstats').then(setStats).catch(() => {});
        window.scrollTo(0, 0);
    }, []);

    return (
        <>
            <section className="page-header">
                <div className="page-bg-text">LEVEL</div>
                <div className="page-header-grid" aria-hidden="true" />
                <div className="page-header-content">
                    <div className="page-tag">{t('level.tag')}</div>
                    <h1 className="page-title">{t('nav.level')}</h1>
                    <p className="page-subtitle">
                        {t('level.subtitle').split('%s')[0]}<code>/rank</code>{t('level.subtitle').split('%s')[1]}
                    </p>
                </div>
            </section>

            <section className="content">
                {error && <p className="notice">{t('level.error')}</p>}
                {!error && !rows && <SkeletonRows n={10} />}
                {rows?.length === 0 && (
                    <EmptyState
                        Icon={IconLevel}
                        title={t('level.emptyTitle')}
                        text={t('level.emptyText')}
                        actions={[{ to: '/devlogs', label: t('common.readDevlogs') }]}
                    />
                )}

                {rows?.length > 0 && (
                    <div className="lvl-list">
                        {rows.map((r, i) => {
                            const base = xpForLevel(r.level);
                            const next = xpForLevel(r.level + 1);
                            const pct = Math.floor(((r.xp - base) / (next - base)) * 100);
                            const name = r.display_name || r.username || r.user_id;
                            return (
                                <div className={`lvl-row${i < 3 ? ` top top-${i + 1}` : ''}`} key={r.user_id}>
                                    <span className="lvl-rank">
                                        {i < 3 && <IconTrophy size={15} style={{ color: MEDAL_COLORS[i] }} />}
                                        <span className="lvl-rank-n">{i + 1}</span>
                                    </span>
                                    {/* Ohne Bild bleibt der Anfangsbuchstabe — kein leeres Loch */}
                                    {r.avatar
                                        ? <img className="lvl-avatar" src={r.avatar} alt="" loading="lazy" />
                                        : <span className="lvl-avatar lvl-avatar-empty">{name.slice(0, 1).toUpperCase()}</span>}
                                    <span className="lvl-name">{name}</span>
                                    <div className="lvl-progress">
                                        <div className="progress"><div className="progress-bar" style={{ width: `${pct}%` }} /></div>
                                    </div>
                                    <span className="lvl-level">{t('level.lv', r.level)}</span>
                                    <span className="lvl-xp">{zahl(r.xp)} XP</span>
                                </div>
                            );
                        })}
                    </div>
                )}

                {stats && <ActivityChart stats={stats} />}
            </section>
        </>
    );
}