const MapView = (() => {
  let map = null;
  let trackLayers = {};  // trackId → { layer, color, markers }
  let currentTrackId = null;

  const COLORS = ['#e74c3c', '#3498db', '#2ecc71', '#f39c12', '#9b59b6', '#1abc9c', '#e67e22', '#34495e'];
  let colorIndex = 0;

  function init() {
    map = L.map('map');

    const osmLayer = L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors',
      maxZoom: 19
    });

    const topoLayer = L.tileLayer('https://{s}.tile.opentopomap.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="https://opentopomap.org">OpenTopoMap</a> contributors',
      maxZoom: 17
    });

    const satelliteLayer = L.tileLayer('https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}', {
      attribution: 'Tiles &copy; Esri &mdash; Source: Esri, USGS, AeroGRID, IGN, and the GIS User Community',
      maxZoom: 19
    });

    const baseMaps = {
      'OpenStreetMap': osmLayer,
      'Topographic': topoLayer,
      'Satellite': satelliteLayer
    };

    osmLayer.addTo(map);
    L.control.layers(baseMaps).addTo(map);
    L.control.scale({ metric: true, imperial: false }).addTo(map);

    // Restore state from URL hash
    restoreFromHash();

    // Save state on map move/zoom
    map.on('moveend zoomend', saveToHash);

    return map;
  }

  function getNextColor() {
    const c = COLORS[colorIndex % COLORS.length];
    colorIndex++;
    return c;
  }

  function addTrack(trackData, trackId) {
    if (trackLayers[trackId]) return trackLayers[trackId].layer;

    const color = getNextColor();
    const lines = [];
    const addedMarkers = [];

    if (!trackData.segments || trackData.segments.length === 0) return null;

    for (const seg of trackData.segments) {
      if (!seg || seg.length === 0) continue;
      const latlngs = seg.map(p => [p[0], p[1]]);
      lines.push(latlngs);
    }

    if (lines.length === 0) return null;

    const layer = L.polyline(lines, { color, weight: 3, opacity: 0.8 });

    // Add start marker (green)
    const firstSeg = trackData.segments.find(s => s && s.length > 0);
    if (firstSeg) {
      const first = firstSeg[0];
      const startMarker = L.circleMarker([first[0], first[1]], {
        radius: 7,
        color: '#27ae60',
        fillColor: '#27ae60',
        fillOpacity: 1,
        weight: 2
      }).bindTooltip('Start: ' + (trackData.meta?.name || 'Track'));
      startMarker.addTo(map);
      addedMarkers.push(startMarker);
    }

    // Add end marker (red)
    const lastSeg = [...trackData.segments].reverse().find(s => s && s.length > 0);
    if (lastSeg) {
      const last = lastSeg[lastSeg.length - 1];
      const endMarker = L.circleMarker([last[0], last[1]], {
        radius: 7,
        color: '#e74c3c',
        fillColor: '#e74c3c',
        fillOpacity: 1,
        weight: 2
      }).bindTooltip('End: ' + (trackData.meta?.name || 'Track'));
      endMarker.addTo(map);
      addedMarkers.push(endMarker);
    }

    layer.addTo(map);
    trackLayers[trackId] = { layer, color, markers: addedMarkers };

    return layer;
  }

  function removeTrack(trackId) {
    if (trackLayers[trackId]) {
      map.removeLayer(trackLayers[trackId].layer);
      // Remove markers
      if (trackLayers[trackId].markers) {
        trackLayers[trackId].markers.forEach(m => map.removeLayer(m));
      }
      delete trackLayers[trackId];
    }
  }

  function clearTracks() {
    Object.keys(trackLayers).forEach(id => removeTrack(id));
    colorIndex = 0;
  }

  function fitTrack(trackId) {
    if (!trackLayers[trackId]) return;
    try {
      const bounds = trackLayers[trackId].layer.getBounds();
      if (bounds.isValid()) {
        map.fitBounds(bounds, { padding: [20, 20] });
      }
    } catch (e) {
      console.warn('fitTrack error:', e);
    }
  }

  function fitAll() {
    const layers = Object.values(trackLayers).map(t => t.layer);
    if (layers.length === 0) return;
    try {
      const group = L.featureGroup(layers);
      const bounds = group.getBounds();
      if (bounds.isValid()) {
        map.fitBounds(bounds, { padding: [20, 20] });
      }
    } catch (e) {
      console.warn('fitAll error:', e);
    }
  }

  function hasTrack(trackId) { return !!trackLayers[trackId]; }

  function saveToHash() {
    if (!map) return;
    const c = map.getCenter();
    const z = map.getZoom();
    const tracks = Object.keys(trackLayers).join(',');
    let hash = `#map=${c.lat.toFixed(5)},${c.lng.toFixed(5)},${z}`;
    if (tracks) hash += `&tracks=${tracks}`;
    if (currentTrackId !== null && currentTrackId !== undefined) hash += `&open=${currentTrackId}`;
    history.replaceState(null, '', hash);
  }

  function restoreFromHash() {
    const params = getHashParams();

    if (params.map) {
      const parts = params.map.split(',');
      if (parts.length === 3) {
        const lat = parseFloat(parts[0]);
        const lng = parseFloat(parts[1]);
        const zoom = parseInt(parts[2]);
        if (!isNaN(lat) && !isNaN(lng) && !isNaN(zoom)) {
          map.setView([lat, lng], zoom);
          return params;
        }
      }
    }

    // Default view
    map.setView([51.505, -0.09], 5);
    return params;
  }

  function getHashParams() {
    const hash = window.location.hash.slice(1);
    const params = {};
    if (!hash) return params;
    hash.split('&').forEach(part => {
      const eqIdx = part.indexOf('=');
      if (eqIdx > 0) {
        const k = part.slice(0, eqIdx);
        const v = part.slice(eqIdx + 1);
        if (k && v) params[k] = v;
      }
    });
    return params;
  }

  function setCurrentTrack(id) {
    currentTrackId = id;
    saveToHash();
  }

  function getMap() { return map; }

  return {
    init,
    addTrack,
    removeTrack,
    clearTracks,
    fitTrack,
    fitAll,
    hasTrack,
    saveToHash,
    restoreFromHash,
    getHashParams,
    setCurrentTrack,
    getMap
  };
})();