import { useState } from 'react';
import LAENDER from '../../data/laender.json';
import CitySearch from './CitySearch.jsx';
import { BY_CODE, CONTINENTS, continentOf, countryName, fmtDay, num } from './laender.js';
import { travelDays, travelRoute } from './route.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, homes, onAddHome, onRemoveHome, busy, onSelectCity }) {
  const [since, setSince] = useState('');
  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: Reisen ab Wohnort, Rundreisen und Ausflüge (siehe route.js)
  const route = travelRoute(visits, cities, homes);
  const days = travelDays(visits, cities, homes);
  const summary = [
    `${route.trips} ${route.trips === 1 ? 'Reise' : 'Reisen'}${homes.length ? ' ab Wohnort' : ''}`,
    route.excursions && `${route.excursions} ${route.excursions === 1 ? 'Ausflug' : 'Ausflüge'}`,
    `${days} Reisetage`,
  ].filter(Boolean).join(' · ');

  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.legs.length ? `${num(Math.round(route.km))} km` : '–'}</strong>
          <span>{route.legs.length ? `Luftlinie · ${summary}` : 'Besuche mit Datum eintragen, um Kilometer zu sehen'}</span>
        </div>
      </div>

      <section className="stat-home" aria-labelledby="stat-wohnort">
        <h2 className="section-title" id="stat-wohnort">Wohnorte</h2>
        {homes.length ? (
          <ul className="stat-homes">
            {homes.map((h) => (
              <li key={h.id}>
                ⌂ <strong>{h.name}</strong> <small>{countryName(h.country)} · {h.since ? `seit ${fmtDay(h.since)}` : 'von Anfang an'}</small>
                <button className="link-btn danger" type="button" disabled={busy} onClick={() => onRemoveHome(h)} aria-label={`Wohnort ${h.name} entfernen`}>✕</button>
              </li>
            ))}
          </ul>
        ) : (
          <p className="hint">Mit Wohnort zählt jede Reise als Hin- und Rückweg ab zuhause.</p>
        )}
        <div className="stat-home-add">
          <label className="stat-home-since">
            <span>Seit</span>
            <input type="date" value={since} onChange={(e) => setSince(e.target.value)} aria-describedby="since-hint" />
          </label>
          <CitySearch mode="home" cities={[]} onAdd={async (r) => { if (await onAddHome({ ...r, since: since || null })) setSince(''); }} busy={busy} />
        </div>
        <p className="hint" id="since-hint">
          „Seit“ leer = von Anfang an. Zog man um oder wohnte länger im Ausland, einen weiteren Wohnort mit Datum eintragen –
          oder beim Besuch „In dieser Zeit hier gewohnt“ wählen.
        </p>
        {route.legs.length > 0 && (
          <details className="stat-route">
            <summary>Wie gerechnet? ({route.legs.length} Teilstrecken)</summary>
            <ol>
              {route.legs.map((l, i) => (
                <li key={i}>
                  <span>{l.from} → {l.to}</span>
                  <small>{l.kind}</small>
                  <strong>{num(Math.round(l.km))} km</strong>
                </li>
              ))}
            </ol>
            {!homes.length && <p className="hint">Ohne Wohnort fehlen Hin- und Heimwege; die Reisen werden direkt nacheinander verbunden.</p>}
          </details>
        )}
      </section>

      <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>
  );
}