/* ============================================================
   BAN YARO — Gassi-Treffen
   Treffen entdecken, erstellen, beitreten
   ============================================================ */

window.Page_walks = (() => {

  let _container     = null;
  let _appState      = null;
  let _data          = [];
  let _view          = 'liste';     // 'liste' | 'karte'
  let _map           = null;
  let _markers       = [];
  let _leafletLoaded = false;
  let _userPos       = null;

  function _esc(s) {
    return String(s || '').replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;');
  }

  // Datum deutsch formatieren: "2026-04-20" → "Sonntag, 20. April 2026"
  function _fmtDate(iso) {
    if (!iso) return '—';
    const d = new Date(iso + 'T12:00:00');
    return d.toLocaleDateString('de-DE', { weekday: 'long', day: 'numeric', month: 'long', year: 'numeric' });
  }

  // Datum kurz: "So, 20.04."
  function _fmtDateShort(iso) {
    if (!iso) return '—';
    const d = new Date(iso + 'T12:00:00');
    return d.toLocaleDateString('de-DE', { weekday: 'short', day: '2-digit', month: '2-digit' });
  }

  function _isToday(iso) {
    return iso === new Date().toISOString().slice(0, 10);
  }

  function _isPast(iso) {
    return iso < new Date().toISOString().slice(0, 10);
  }

  // ----------------------------------------------------------
  // INIT
  // ----------------------------------------------------------
  async function init(container, appState) {
    _container = container;
    _appState  = appState;
    _render();
    try { _userPos = await API.getLocation(); } catch {}
    _loadData();
  }

  function refresh() { _loadData(); }
  function onDogChange() {}
  function openNew() { _showCreateForm(); }

  // ----------------------------------------------------------
  // RENDER — Grundstruktur
  // ----------------------------------------------------------
  function _render() {
    _container.innerHTML = `
      <div class="walks-layout">

        <!-- Toolbar -->
        <div class="by-toolbar">
          <div class="walks-view-toggle" id="walks-view-toggle">
            <button class="walks-view-btn active" data-view="liste">${UI.icon('list')} Liste</button>
            <button class="walks-view-btn" data-view="karte">${UI.icon('map-trifold')} Karte</button>
          </div>
          <button class="btn btn-primary btn-sm" id="walks-create-btn">${UI.icon('plus')} Treffen planen</button>
        </div>

        <!-- Liste -->
        <div id="walks-list-view" class="walks-content">
          <div id="walks-list">
            <p style="color:var(--c-text-secondary);text-align:center;padding:var(--space-8)">Lädt…</p>
          </div>
        </div>

        <!-- Karte -->
        <div id="walks-map-view" class="walks-content" style="display:none">
          <div id="walks-map" class="walks-map"></div>
        </div>

      </div>
    `;

    document.getElementById('walks-view-toggle').addEventListener('click', e => {
      const btn = e.target.closest('.walks-view-btn');
      if (!btn) return;
      _switchView(btn.dataset.view);
    });

    document.getElementById('walks-create-btn').addEventListener('click', () => {
      if (!_appState.user) {
        UI.toast.warning('Bitte zuerst anmelden.');
        App.navigate('settings');
        return;
      }
      _showCreateForm();
    });
  }

  function _switchView(view) {
    _view = view;
    document.querySelectorAll('.walks-view-btn').forEach(b =>
      b.classList.toggle('active', b.dataset.view === view));
    document.getElementById('walks-list-view').style.display = view === 'liste' ? '' : 'none';
    document.getElementById('walks-map-view').style.display  = view === 'karte' ? '' : 'none';

    if (view === 'karte') {
      _loadLeaflet().then(() => {
        _initMap();
        setTimeout(() => _map?.invalidateSize(), 50);
        setTimeout(() => _map?.invalidateSize(), 300);
      });
    }
  }

  // ----------------------------------------------------------
  // Daten laden
  // ----------------------------------------------------------
  async function _loadData() {
    try {
      _data = await API.walks.list(
        _userPos?.lat ?? null,
        _userPos?.lon ?? null
      );
      _renderList();
      _renderMarkers();
    } catch (err) {
      UI.toast.error(err.message || 'Fehler beim Laden.');
    }
  }

  // ----------------------------------------------------------
  // Liste rendern
  // ----------------------------------------------------------
  function _renderList() {
    const el = document.getElementById('walks-list');
    if (!el) return;

    if (!_data.length) {
      el.innerHTML = `
        <div style="text-align:center;padding:var(--space-10) var(--space-4)">
          <div style="font-size:3rem;margin-bottom:var(--space-3)">${UI.icon('dog')}</div>
          <p style="color:var(--c-text-secondary)">Noch keine Treffen in deiner Nähe.</p>
          <button class="btn btn-primary" style="margin-top:var(--space-4)" id="walks-first-btn">
            Erstes Treffen planen
          </button>
        </div>`;
      document.getElementById('walks-first-btn')?.addEventListener('click', _showCreateForm);
      return;
    }

    // Heute + zukünftige Treffen
    const heute    = _data.filter(w => _isToday(w.datum));
    const upcoming = _data.filter(w => !_isToday(w.datum) && !_isPast(w.datum));

    let html = '';

    if (heute.length) {
      html += `<div class="by-section-label">${UI.icon('star')} Heute</div>`;
      html += heute.map(w => _walkCardHTML(w)).join('');
    }

    if (upcoming.length) {
      html += `<div class="by-section-label">${UI.icon('calendar-dots')} Demnächst</div>`;
      html += upcoming.map(w => _walkCardHTML(w)).join('');
    }

    el.innerHTML = `<div class="walks-list-inner">${html}</div>`;

    el.querySelectorAll('.walks-card').forEach(card => {
      card.addEventListener('click', () => _openDetail(parseInt(card.dataset.id)));
    });
  }

  function _walkCardHTML(w) {
    const isOwn    = _appState.user?.id === w.user_id;
    const isFull   = w.status === 'voll' || w.teilnehmer_count >= w.max_teilnehmer;
    const today    = _isToday(w.datum);
    const spots    = w.max_teilnehmer - w.teilnehmer_count;

    return `
      <div class="walks-card ${today ? 'walks-card--today' : ''}" data-id="${w.id}">
        <div class="walks-card-date">
          <div class="walks-card-day">${_fmtDateShort(w.datum)}</div>
          <div class="walks-card-time">${w.uhrzeit}</div>
        </div>
        <div class="walks-card-body">
          <div class="walks-card-title">${_esc(w.titel)}</div>
          ${w.ort_name ? `<div class="walks-card-ort">${UI.icon('map-pin')} ${_esc(w.ort_name)}</div>` : ''}
          <div class="walks-card-meta">
            <span class="walks-badge ${isFull ? 'walks-badge--full' : 'walks-badge--open'}">
              ${isFull ? '🔴 Voll' : `🟢 ${spots} Platz${spots !== 1 ? 'e' : ''} frei`}
            </span>
            <span class="walks-badge">${UI.icon('paw-print')} ${w.teilnehmer_count}/${w.max_teilnehmer}</span>
            ${isOwn ? '<span class="walks-badge walks-badge--own">Mein Treffen</span>' : ''}
          </div>
        </div>
        <div class="walks-card-arrow">›</div>
      </div>`;
  }

  // ----------------------------------------------------------
  // Leaflet + Karte
  // ----------------------------------------------------------
  async function _loadLeaflet() {
    if (_leafletLoaded || window.L) { _leafletLoaded = true; return; }
    const link = document.createElement('link');
    link.rel = 'stylesheet'; link.href = '/css/leaflet.css';
    document.head.appendChild(link);
    await new Promise(resolve => {
      const s = document.createElement('script');
      s.src = '/js/leaflet.js'; s.onload = resolve;
      document.head.appendChild(s);
    });
    _leafletLoaded = true;
  }

  function _initMap() {
    const el = document.getElementById('walks-map');
    if (!el || !window.L || _map) return;
    const center = _userPos ? [_userPos.lat, _userPos.lon] : [51.1657, 10.4515];
    _map = L.map('walks-map', { zoomControl: true, attributionControl: false })
             .setView(center, _userPos ? 12 : 6);
    L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { maxZoom: 19 }).addTo(_map);
    _renderMarkers();
  }

  function _renderMarkers() {
    if (!_map || !window.L) return;
    _markers.forEach(m => m.remove());
    _markers = [];
    _data.forEach(w => {
      const isFull = w.status === 'voll' || w.teilnehmer_count >= w.max_teilnehmer;
      const color  = _isToday(w.datum) ? 'var(--c-primary)' : (isFull ? '#6B7280' : '#22C55E');
      const icon   = L.divIcon({
        className: '',
        html: `<div style="background:${color};color:#fff;font-size:14px;font-weight:700;
          width:32px;height:32px;border-radius:50%;display:flex;align-items:center;
          justify-content:center;box-shadow:0 2px 5px rgba(0,0,0,0.3);
          border:2px solid rgba(255,255,255,0.8)">${UI.icon('dog')}</div>`,
        iconSize: [32, 32], iconAnchor: [16, 16],
      });
      const m = L.marker([w.lat, w.lon], { icon })
        .addTo(_map)
        .bindTooltip(`${w.titel} · ${_fmtDateShort(w.datum)} ${w.uhrzeit}`, { direction: 'top', offset: [0,-16] })
        .on('click', () => _openDetail(w.id));
      _markers.push(m);
    });
  }

  // ----------------------------------------------------------
  // Detail-Modal
  // ----------------------------------------------------------
  async function _openDetail(walkId) {
    let walk;
    try {
      walk = await API.walks.get(walkId);
    } catch (err) {
      UI.toast.error(err.message);
      return;
    }

    const isOwn      = _appState.user?.id === walk.user_id;
    const isJoined   = walk.teilnehmer?.some(t => t.user_id === _appState.user?.id);
    const isFull     = walk.status === 'voll' || walk.teilnehmer_count >= walk.max_teilnehmer;
    const isPast     = _isPast(walk.datum);
    const spots      = walk.max_teilnehmer - walk.teilnehmer_count;

    const teilnehmerHTML = walk.teilnehmer?.length
      ? walk.teilnehmer.map(t => `
          <div class="walks-participant">
            <span class="walks-participant-name">${UI.icon('user')} ${_esc(t.user_name)}</span>
            ${t.hunde ? `<span class="walks-participant-hunde">${UI.icon('dog')} ${_esc(t.hunde)}</span>` : ''}
          </div>`).join('')
      : `<p style="color:var(--c-text-muted)">Noch keine Teilnehmer.</p>`;

    const body = `
      <div class="walks-detail-header">
        <div class="walks-detail-date">
          ${_fmtDate(walk.datum)}<br>
          <strong>um ${walk.uhrzeit} Uhr</strong>
        </div>
        ${walk.ort_name ? `<div style="margin-top:var(--space-2);color:var(--c-text-secondary)">${UI.icon('map-pin')} ${_esc(walk.ort_name)}</div>` : ''}
        <div style="margin-top:var(--space-2);display:flex;gap:var(--space-2);flex-wrap:wrap">
          <span class="walks-badge ${isFull ? 'walks-badge--full' : 'walks-badge--open'}">
            ${isFull ? '🔴 Voll' : `🟢 ${spots} Platz${spots !== 1 ? 'e' : ''} frei`}
          </span>
          <span class="walks-badge">${UI.icon('paw-print')} ${walk.teilnehmer_count}/${walk.max_teilnehmer} Teilnehmer</span>
          ${isOwn ? '<span class="walks-badge walks-badge--own">Dein Treffen</span>' : ''}
        </div>
      </div>

      ${walk.beschreibung ? `
        <p style="margin:var(--space-4) 0;color:var(--c-text-secondary)">${_esc(walk.beschreibung)}</p>
      ` : ''}

      <div class="walks-detail-section">
        <div class="walks-detail-section-label">Teilnehmer</div>
        ${teilnehmerHTML}
      </div>

      <p style="color:var(--c-text-muted);font-size:0.8rem;margin-top:var(--space-4)">
        Veranstaltet von ${_esc(walk.veranstalter_name || 'Unbekannt')}
      </p>
    `;

    let footer;
    if (isOwn) {
      footer = `
        <button type="button" class="btn btn-ghost btn-sm" id="wd-cancel-walk" style="color:var(--c-danger)">Stornieren</button>
        <button type="button" class="btn btn-secondary flex-1" id="wd-edit">Bearbeiten</button>
        <button type="button" class="btn btn-primary flex-1" id="wd-close">Schließen</button>
      `;
    } else if (!_appState.user) {
      footer = `
        <button type="button" class="btn btn-secondary flex-1" id="wd-close">Schließen</button>
        <button type="button" class="btn btn-primary flex-1" id="wd-login">Anmelden zum Beitreten</button>
      `;
    } else if (isJoined) {
      footer = `
        <button type="button" class="btn btn-ghost btn-sm" id="wd-leave" style="color:var(--c-danger)">Nicht mehr teilnehmen</button>
        <button type="button" class="btn btn-primary flex-1" id="wd-close">Schließen</button>
      `;
    } else if (isPast || isFull) {
      footer = `<button type="button" class="btn btn-primary flex-1" id="wd-close">Schließen</button>`;
    } else {
      footer = `
        <button type="button" class="btn btn-secondary flex-1" id="wd-close">Schließen</button>
        <button type="button" class="btn btn-primary flex-1" id="wd-join">${UI.icon('dog')} Mitmachen</button>
      `;
    }

    UI.modal.open({ title: `${UI.icon('dog')} ${walk.titel}`, body, footer });

    document.getElementById('wd-close')?.addEventListener('click', UI.modal.close);

    document.getElementById('wd-login')?.addEventListener('click', () => {
      UI.modal.close();
      App.navigate('settings');
    });

    document.getElementById('wd-edit')?.addEventListener('click', () => {
      UI.modal.close();
      _showEditForm(walk);
    });

    document.getElementById('wd-cancel-walk')?.addEventListener('click', async () => {
      const ok = await UI.modal.confirm({
        title: 'Treffen stornieren?',
        message: 'Alle Teilnehmer werden benachrichtigt. Nicht rückgängig.',
        confirmText: 'Stornieren', danger: true,
      });
      if (!ok) return;
      try {
        await API.walks.cancel(walk.id);
        _data = _data.filter(w => w.id !== walk.id);
        UI.modal.close();
        _renderList();
        _renderMarkers();
        UI.toast.success('Treffen storniert.');
      } catch (err) { UI.toast.error(err.message); }
    });

    document.getElementById('wd-join')?.addEventListener('click', () => {
      UI.modal.close();
      _showJoinForm(walk);
    });

    document.getElementById('wd-leave')?.addEventListener('click', async () => {
      const ok = await UI.modal.confirm({
        title: 'Nicht mehr teilnehmen?',
        message: `Du verlässt „${walk.titel}".`,
        confirmText: 'Austreten',
      });
      if (!ok) return;
      try {
        const res = await API.walks.leave(walk.id);
        const idx = _data.findIndex(w => w.id === walk.id);
        if (idx !== -1) _data[idx].teilnehmer_count = res.teilnehmer_count;
        UI.modal.close();
        _renderList();
        UI.toast.success('Du nimmst nicht mehr teil.');
      } catch (err) { UI.toast.error(err.message); }
    });
  }

  // ----------------------------------------------------------
  // Beitreten-Formular (Hunde wählen)
  // ----------------------------------------------------------
  function _showJoinForm(walk) {
    const dogs = _appState.dogs || [];
    const dogsHtml = dogs.length
      ? dogs.map(d => `
          <label style="display:flex;align-items:center;gap:var(--space-2);cursor:pointer;
                         padding:var(--space-2) 0">
            <input type="checkbox" name="dog" value="${d.id}" checked>
            ${UI.icon('dog')} ${_esc(d.name)}
          </label>`).join('')
      : `<p style="color:var(--c-text-muted)">Keine Hunde im Profil — du kannst trotzdem mitmachen.</p>`;

    const body = `
      <p style="color:var(--c-text-secondary);margin-bottom:var(--space-4)">
        ${_fmtDate(walk.datum)} um ${walk.uhrzeit} Uhr<br>
        ${walk.ort_name ? `${UI.icon('map-pin')} ${_esc(walk.ort_name)}` : ''}
      </p>
      <div class="form-group">
        <label class="form-label">Mit welchen Hunden?</label>
        ${dogsHtml}
      </div>
    `;

    const footer = `
      <button type="button" class="btn btn-secondary flex-1" id="join-cancel">Abbrechen</button>
      <button type="button" class="btn btn-primary flex-1" id="join-confirm">${UI.icon('dog')} Mitmachen</button>
    `;

    UI.modal.open({ title: `Treffen beitreten`, body, footer });

    document.getElementById('join-cancel')?.addEventListener('click', UI.modal.close);

    document.getElementById('join-confirm')?.addEventListener('click', async () => {
      const btn = document.getElementById('join-confirm');
      const checked = [...document.querySelectorAll('[name="dog"]:checked')];
      const dogIds  = checked.map(cb => parseInt(cb.value));

      await UI.asyncButton(btn, async () => {
        const res = await API.walks.join(walk.id, dogIds);
        const idx = _data.findIndex(w => w.id === walk.id);
        if (idx !== -1) _data[idx].teilnehmer_count = res.teilnehmer_count;
        UI.modal.close();
        _renderList();
        _renderMarkers();
        UI.toast.success(`Du nimmst teil! 🎉`);
      });
    });
  }

  // ----------------------------------------------------------
  // Treffen erstellen
  // ----------------------------------------------------------
  function _showCreateForm(prefill = {}) {
    const today = new Date().toISOString().slice(0, 10);
    _showWalkForm(null, { datum: today, uhrzeit: '10:00', ...prefill });
  }

  function _showEditForm(walk) {
    _showWalkForm(walk);
  }

  function _showWalkForm(walk, defaults = {}) {
    const isEdit = !!walk;
    const v = walk || defaults;

    const body = `
      <form id="walk-form" autocomplete="off">

        <div class="form-group">
          <label class="form-label">Titel *</label>
          <input class="form-control" type="text" name="titel"
                 value="${_esc(v.titel || '')}"
                 placeholder="z. B. Sonntagsspaziergang im Stadtpark" required>
        </div>

        <div style="display:grid;grid-template-columns:1fr 1fr;gap:var(--space-3)">
          <div class="form-group">
            <label class="form-label">Datum *</label>
            <input class="form-control" type="date" name="datum"
                   value="${_esc(v.datum || '')}" required>
          </div>
          <div class="form-group">
            <label class="form-label">Uhrzeit *</label>
            <input class="form-control" type="time" name="uhrzeit"
                   value="${_esc(v.uhrzeit || '10:00')}" required>
          </div>
        </div>

        <div class="form-group">
          <label class="form-label">Treffpunkt</label>
          <div style="display:flex;gap:var(--space-2)">
            <input class="form-control" type="text" name="ort_name"
                   value="${_esc(v.ort_name || '')}"
                   placeholder="z. B. Parkeingang Nordseite, U-Bahn Volkspark"
                   style="flex:1">
            <button type="button" class="btn btn-secondary" id="walk-gps-btn" title="GPS">${UI.icon('map-pin')}</button>
          </div>
          <input type="hidden" name="lat" id="walk-lat" value="${v.lat || ''}">
          <input type="hidden" name="lon" id="walk-lon" value="${v.lon || ''}">
          <small id="walk-gps-hint" style="color:var(--c-text-secondary)">
            ${v.lat ? `${UI.icon('check')} Position gespeichert` : 'GPS-Button für aktuellen Standort'}
          </small>
        </div>

        <div class="form-group">
          <label class="form-label">Max. Teilnehmer</label>
          <input class="form-control" type="number" name="max_teilnehmer"
                 value="${v.max_teilnehmer || 10}" min="2" max="50">
        </div>

        <div class="form-group">
          <label class="form-label">Beschreibung <span style="color:var(--c-text-secondary)">(optional)</span></label>
          <textarea class="form-control" name="beschreibung" rows="3"
                    placeholder="Treffpunkt-Details, Streckenlänge, Hundefreundlichkeit…">${_esc(v.beschreibung || '')}</textarea>
        </div>

      </form>
    `;

    const footer = `
      <div style="display:flex;flex-direction:column;gap:var(--space-2);width:100%">
        <button type="submit" form="walk-form" class="btn btn-primary" style="width:100%">
          ${isEdit ? 'Speichern' : `${UI.icon('calendar-dots')} Treffen planen`}
        </button>
        <button type="button" class="btn btn-secondary" id="wf-cancel">Abbrechen</button>
      </div>
    `;

    UI.modal.open({ title: isEdit ? 'Treffen bearbeiten' : `${UI.icon('dog')} Treffen planen`, body, footer });

    document.getElementById('wf-cancel')?.addEventListener('click', UI.modal.close);

    document.getElementById('walk-gps-btn')?.addEventListener('click', async () => {
      const btn = document.getElementById('walk-gps-btn');
      UI.setLoading(btn, true);
      try {
        const pos = await API.getLocation({ enableHighAccuracy: true });
        _userPos  = pos;
        document.getElementById('walk-lat').value  = pos.lat;
        document.getElementById('walk-lon').value  = pos.lon;
        document.getElementById('walk-gps-hint').innerHTML = `${UI.icon('check')} Standort ermittelt`;
      } catch { UI.toast.error('GPS nicht verfügbar.'); }
      UI.setLoading(btn, false);
    });

    document.getElementById('walk-form')?.addEventListener('submit', async e => {
      e.preventDefault();
      const btn = document.querySelector('[form="walk-form"][type="submit"]') || e.target.querySelector('[type="submit"]');
      const fd  = UI.formData(e.target);

      if (!fd.lat || !fd.lon) {
        UI.toast.warning('Bitte GPS-Position ermitteln.');
        return;
      }

      await UI.asyncButton(btn, async () => {
        const payload = {
          titel:          fd.titel?.trim(),
          datum:          fd.datum,
          uhrzeit:        fd.uhrzeit,
          lat:            parseFloat(fd.lat),
          lon:            parseFloat(fd.lon),
          ort_name:       fd.ort_name  || null,
          max_teilnehmer: parseInt(fd.max_teilnehmer) || 10,
          beschreibung:   fd.beschreibung || null,
        };

        if (isEdit) {
          const updated = await API.walks.update(walk.id, payload);
          const idx = _data.findIndex(w => w.id === walk.id);
          if (idx !== -1) _data[idx] = { ..._data[idx], ...updated };
          UI.toast.success('Treffen aktualisiert.');
        } else {
          const created = await API.walks.create(payload);
          _data.unshift({ ...created, teilnehmer_count: 0 });
          // Beim eigenen neuen Treffen gleich beitreten?
          // Nein — Veranstalter ist automatisch dabei (für Teilnehmer-Sicht)
          UI.toast.success('Treffen geplant! 🎉');
        }

        UI.modal.close();
        _renderList();
        _renderMarkers();
      });
    });
  }

  return { init, refresh, onDogChange, openNew };

})();