import LAENDER from '../../data/laender.json';
import { BY_CODE, CONTINENTS, continentOf, countryName, distanceKm, num } from './laender.js';

const pct = (part, total) => (total ? (part / total) * 100 : 0);
const fmtPct = (p) => `${p.toLocaleString('de-DE', { maximumFractionDigits: p < 10 ? 1 : 0 })} %`;
const TOTAL_AREA = LAENDER.reduce((s, c) => s + (c.area || 0), 0);

/**
 * Statistik: Länder (Welt und je Kontinent), Fläche, äußerste Punkte, Kilometer entlang der Zeitleiste.
 * Grundlage für "Welt": alle Länder und Gebiete der Länderdaten (world-countries).
 */
export default function TravelStats({ visited, cities, visits, wishes, onSelectCity }) {
  const codes = [...visited].filter((c) => BY_CODE.has(c));
  const area = codes.reduce((s, c) => s + (BY_CODE.get(c).area || 0), 0);
  const continents = CONTINENTS.map((name) => {
    const total = LAENDER.filter((c) => c.continent === name).length;
    const seen = codes.filter((c) => continentOf(c) === name).length;
    return { name, total, seen };
  }).filter((c) => c.total);

  // Äußerste Punkte (nur besuchte Städte)
  const extreme = (pick) => (cities.length ? cities.reduce((a, b) => (pick(b) > pick(a) ? b : a)) : null);
  const points = [
    ['Nördlichster Ort', extreme((c) => c.lat), (c) => `${c.lat.toFixed(1).replace('.', ',')}° N`],
    ['Südlichster Ort', extreme((c) => -c.lat), (c) => `${Math.abs(c.lat).toFixed(1).replace('.', ',')}° ${c.lat < 0 ? 'S' : 'N'}`],
    ['Östlichster Ort', extreme((c) => c.lon), (c) => `${Math.abs(c.lon).toFixed(1).replace('.', ',')}° ${c.lon < 0 ? 'W' : 'O'}`],
    ['Westlichster Ort', extreme((c) => -c.lon), (c) => `${Math.abs(c.lon).toFixed(1).replace('.', ',')}° ${c.lon < 0 ? 'W' : 'O'}`],
  ];

  // Kilometer: Besuche in zeitlicher Reihenfolge, Luftlinie von Ort zu Ort
  const byId = new Map(cities.map((c) => [c.id, c]));
  const route = [...visits].sort((a, b) => a.dateFrom.localeCompare(b.dateFrom)).map((v) => byId.get(v.cityId)).filter(Boolean);
  let km = 0;
  for (let i = 1; i < route.length; i += 1) if (route[i].id !== route[i - 1].id) km += distanceKm(route[i - 1], route[i]);
  const days = visits.reduce((s, v) => s + 1 + (v.dateTo ? Math.round((new Date(v.dateTo) - new Date(v.dateFrom)) / 864e5) : 0), 0);

  return (
    <div className="travel-stats">
      <div className="stat-tiles">
        <div className="stat-tile"><strong>{fmtPct(pct(codes.length, LAENDER.length))}</strong><span>der Welt ({codes.length} von {LAENDER.length} Ländern und Gebieten)</span></div>
        <div className="stat-tile"><strong>{fmtPct(pct(area, TOTAL_AREA))}</strong><span>der Landfläche ({num(Math.round(area))} km²)</span></div>
        <div className="stat-tile"><strong>{cities.length}</strong><span>{cities.length === 1 ? 'Stadt' : 'Städte'} besucht · {wishes} auf der Wunschliste</span></div>
        <div className="stat-tile">
          <strong>{route.length > 1 ? `${num(Math.round(km))} km` : '–'}</strong>
          <span>{route.length > 1 ? `Luftlinie entlang ${visits.length} Besuchen (${days} Reisetage)` : 'Besuche mit Datum eintragen, um Kilometer zu sehen'}</span>
        </div>
      </div>

      <section className="stat-continents" aria-labelledby="stat-kontinente">
        <h2 className="section-title" id="stat-kontinente">Kontinente</h2>
        {continents.map((c) => (
          <div key={c.name} className="meter">
            <div className="meter-label"><span>{c.name}</span><strong>{c.seen} / {c.total} · {fmtPct(pct(c.seen, c.total))}</strong></div>
            <span className="meter-bar"><i style={{ width: `${pct(c.seen, c.total)}%` }} /></span>
          </div>
        ))}
      </section>

      {cities.length > 0 && (
        <section aria-labelledby="stat-punkte">
          <h2 className="section-title" id="stat-punkte">Äußerste Punkte</h2>
          <dl className="info-facts stat-points">
            {points.map(([label, city, fmt]) => (
              <div key={label}>
                <dt>{label}</dt>
                <dd>
                  <button type="button" className="link-btn" onClick={() => onSelectCity(city)}>
                    {BY_CODE.get(city.country)?.flag} {city.name}
                  </button>
                  <small> {countryName(city.country)} · {fmt(city)}</small>
                </dd>
              </div>
            ))}
          </dl>
        </section>
      )}
    </div>
  );
}