import { useEffect, useState } from 'react';
import { apiGet } from '../api.js';
import { Markdown } from '../markdown.jsx';

const dueFmt = new Intl.DateTimeFormat('de-DE', { month: 'long', year: 'numeric' });

/** Milestone-Gruppe bestimmen: Fertig / In Arbeit / Geplant */
function groupOf(m) {
    if (m.state === 'closed') return 'done';
    return m.closed > 0 ? 'active' : 'planned';
}

const GROUPS = [
    { id: 'active', tag: '// In Arbeit', empty: 'Gerade nichts in Arbeit.' },
    { id: 'planned', tag: '// Geplant', empty: null },
    { id: 'done', tag: '// Fertig', empty: null },
];

function Milestone({ m }) {
    const total = m.open + m.closed;
    const pct = total > 0 ? Math.round((m.closed / total) * 100) : m.state === 'closed' ? 100 : 0;
    return (
        <article className="card milestone">
            <div className="card-meta">
                <span className="milestone-title">{m.title}</span>
                {m.due_on && m.state !== 'closed' && (
                    <span className="card-rel">Ziel: {dueFmt.format(new Date(m.due_on))}</span>
                )}
            </div>
            {m.description && (
                <div className="card-body">
                    <Markdown text={m.description} />
                </div>
            )}
            <div className="progress">
                <div className="progress-bar" style={{ width: `${pct}%` }} />
            </div>
            <div className="progress-info">
                <span>{pct}%</span>
                {total > 0 && <span>{m.closed} / {total} Aufgaben</span>}
            </div>
        </article>
    );
}

/** GitHub-Style-Heatmap: 52 Wochen × 7 Tage */
function Heatmap({ days }) {
    const byDay = new Map(days.map((d) => [d.day, d.n]));
    const max = Math.max(1, ...days.map((d) => d.n));
    const today = new Date();
    // Start: Montag vor ~52 Wochen
    const start = new Date(today.getTime() - 364 * 86400000);
    start.setDate(start.getDate() - ((start.getDay() + 6) % 7));

    const weeks = [];
    for (let w = 0; w < 53; w++) {
        const col = [];
        for (let d = 0; d < 7; d++) {
            const date = new Date(start.getTime() + (w * 7 + d) * 86400000);
            if (date > today) break;
            const key = date.toISOString().slice(0, 10);
            const n = byDay.get(key) ?? 0;
            const level = n === 0 ? 0 : Math.min(4, Math.ceil((n / max) * 4));
            col.push(
                <span
                    key={d}
                    className={`hm-cell hm-${level}`}
                    title={`${key}: ${n} Commit${n === 1 ? '' : 's'}`}
                />
            );
        }
        weeks.push(<span className="hm-week" key={w}>{col}</span>);
    }
    const total = days.reduce((sum, d) => sum + d.n, 0);
    return (
        <div className="roadmap-group">
            <h2 className="settings-title">// Aktivität — {total} Commits in 12 Monaten</h2>
            <div className="hm-wrap">{weeks}</div>
        </div>
    );
}

export default function Roadmap() {
    const [data, setData] = useState(null);
    const [wishes, setWishes] = useState([]);
    const [heatmap, setHeatmap] = useState(null);
    const [error, setError] = useState(false);

    useEffect(() => {
        apiGet('/api/roadmap').then(setData).catch(() => setError(true));
        apiGet('/api/wishes').then((d) => setWishes(d.wishes)).catch(() => {});
        apiGet('/api/heatmap').then((d) => setHeatmap(d.days)).catch(() => {});
        window.scrollTo(0, 0);
    }, []);

    return (
        <>
            <section className="page-header">
                <div className="page-bg-text">ROADMAP</div>
                <div className="page-header-grid" aria-hidden="true" />
                <div className="page-header-content">
                    <div className="page-tag">// Wohin die Reise geht</div>
                    <h1 className="page-title">Roadmap</h1>
                    <p className="page-subtitle">
                        Meilensteine direkt aus der Entwicklung — live aus dem Issue-Tracker.
                    </p>
                </div>
            </section>

            <section className="content">
                {error && <p className="notice">Roadmap konnte nicht geladen werden.</p>}
                {!error && !data && <p className="notice">Lade …</p>}
                {data?.milestones.length === 0 && (
                    <p className="notice">Noch keine Meilensteine angelegt.</p>
                )}

                {heatmap && heatmap.length > 0 && <Heatmap days={heatmap} />}

                {wishes.length > 0 && (
                    <div className="roadmap-group">
                        <h2 className="settings-title">// Community-Wünsche</h2>
                        {wishes.map((w, i) => (
                            <div className="wish-row" key={`${w.created_at}-${i}`}>
                                <span className="wish-score">👍 {w.score}</span>
                                <span className="wish-idea">{w.idea}</span>
                                <span className="wish-author">{w.author}</span>
                            </div>
                        ))}
                        <p className="notice" style={{ padding: '.6rem 0 0' }}>
                            Eigene Idee? Im Discord einfach <code>/wunsch</code> benutzen.
                        </p>
                    </div>
                )}

                {GROUPS.map(({ id, tag, empty }) => {
                    const items = (data?.milestones ?? []).filter((m) => groupOf(m) === id);
                    if (items.length === 0 && !empty) return null;
                    return (
                        <div className="roadmap-group" key={id}>
                            <h2 className="settings-title">{tag}</h2>
                            {items.length === 0 && <p className="notice">{empty}</p>}
                            {items.map((m) => (
                                <Milestone m={m} key={m.title} />
                            ))}
                        </div>
                    );
                })}
            </section>
        </>
    );
}