/***********************************************************************
 * Copyright © 2024 Guilhem Moulin <info@guilhem.se>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 **********************************************************************/

import Map from 'ol/Map.js';
import View from 'ol/View.js';
import TileLayer from 'ol/layer/Tile.js';

import WMTS from 'ol/source/WMTS.js';
import WMTSTileGrid from 'ol/tilegrid/WMTS.js';

import FullScreen from 'ol/control/FullScreen.js';
import ScaleLine from 'ol/control/ScaleLine.js';
import Zoom from 'ol/control/Zoom.js';
import ZoomSlider from 'ol/control/ZoomSlider.js';

import Overlay from 'ol/Overlay.js';

import MVT from 'ol/format/MVT.js';
import VectorTileLayer from 'ol/layer/VectorTile.js';
import VectorTile from 'ol/source/VectorTile.js';
import { createXYZ } from 'ol/tilegrid.js';

import VectorLayer from 'ol/layer/Vector.js';
import VectorSource from 'ol/source/Vector.js';

import CircleStyle from 'ol/style/Circle.js';
import Fill from 'ol/style/Fill.js';
import Icon from 'ol/style/Icon.js';
import RegularShape from 'ol/style/RegularShape.js';
import Stroke from 'ol/style/Stroke.js';
import Style from 'ol/style/Style.js';

import proj4 from 'proj4';
import { get as getProjection } from 'ol/proj.js';
import { register as registerProjection } from 'ol/proj/proj4.js';

import { Modal, Popover } from 'bootstrap';

import './style.css';


proj4.defs('EPSG:3006', '+proj=utm +zone=33 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs +type=crs');
registerProjection(proj4);
const projection = getProjection('EPSG:3006');


/* Lantmäteriet uses a tile-scheme where the origin (top-left corner) is
 * at N8500000 E-1200000 (SWEREF99 TM), where each tile is 256x256
 * pixels, and where the resolution at level 0 is 4096m per pixel
 * (each side is 1048.576km long).
 *
 *     https://www.lantmateriet.se/globalassets/geodata/geodatatjanster/tb_twk_visning_cache_v1.1.0.pdf
 *     https://www.lantmateriet.se/globalassets/geodata/geodatatjanster/tb_twk_visning-oversiktlig_v1.0.3.pdf
 *
 * We set the extent to a 4x4 tiles square at level 2 (1024px =
 * 1048.576km per side) somehow centered on Norrbotten and Västerbotten,
 * and zoom in from there.  This represent a TILEROW (x) offset of 5,
 * and a TILECOL (y) offset of 2.
 */
const extent = [110720, 6927136, 1159296, 7975712];

/* XXX using the topowebbcache WMTS is fine for testing (as it
 * doesn't require authentication) but not in production in a public
 * instance as doing so would violate its current terms of use (as
 * of January 2024 it's not CC0 open data).  See
 *
 *   https://www.lantmateriet.se/sv/om-lantmateriet/Rattsinformation/upphovsratt-och-publicering-av-lantmateriets-geografiska-information/
 *   https://www.lantmateriet.se/sv/kartor/vara-karttjanster/min-karta/#anchor-2
 *   https://help.locusmap.eu/topic/support-for-swedish-lantmateriets-min-karta-wms
 *
 *  More precise background maps might be available in the future
 *  as open data, though:
 *
 *    https://www.lantmateriet.se/sv/om-lantmateriet/press/nyheter/lantmateriets-arbete-mot-oppna-data-i-full-gang/
 */
const baseMapSource = new WMTS({
  url: undefined,
  version: '1.0.0',
  style: 'default',
  matrixSet: '3006',
  format: 'image/png',
  tileGrid: new WMTSTileGrid({
    extent: extent,
    // https://www.lantmateriet.se/globalassets/geodata/geodatatjanster/tb_twk_visning-oversiktlig_v1.0.3.pdf
    tileSize: 256,
    origin: [-1200000, 8500000],
    resolutions: [4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8],
    matrixIds: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
  }),
  projection: projection,
  wrapX: false,
  crossOrigin: 'anonymous',
});


const view = new View({
  projection: projection,
  extent: extent,
  showFullExtent: true,
  /* center of the bbox of the Norrbotten and Västerbotten geometries */
  center: [694767.48, 7338176.57],
  zoom: 1,
  enableRotation: false,
  resolutions: [1024, 512, 256, 128, 64, 32, 16, 8],
  constrainResolution: false,
});

let baseMapLayer = 'topowebb';
(function() {
  const params = new URLSearchParams(window.location.hash.substring(1));
  const x = parseFloat(params.get('x'));
  const y = parseFloat(params.get('y'));
  if (!isNaN(x) && !isNaN(y)) {
    view.setCenter([x, y]);
  }
  const z = parseFloat(params.get('z'));
  if (!isNaN(z)) {
    view.setZoom(z);
  }

  if (params.has('basemap')) {
    baseMapLayer = params.get('basemap');
  }
  baseMapSource.setUrl(`https://minkarta.lantmateriet.se/map/topowebbcache?LAYER=${encodeURIComponent(baseMapLayer)}`);
})();


const map = new Map({
  controls: [],
  view: view,
  layers: [
    new TileLayer({
      source: baseMapSource
    }),
  ],
  target: document.getElementById('map'),
});

const popup = document.getElementById('popup');
const featureOverlaySource = new VectorSource();

/* move the control container to the viewport */
const container = document.getElementById('map-control-container');
(function() {
  const container0 = map.getViewport().getElementsByClassName('ol-overlaycontainer-stopevent')[0];
  container0.appendChild(document.getElementById('zoom-control'));
  container0.appendChild(container);
  container0.appendChild(document.getElementById('modal-info'));

  const backdrop = document.createElement('div');
  container0.appendChild(backdrop);
  backdrop.id = 'modal-info-backdrop';
})();

/* zoom in/out */
(function() {
  const zoomInLabel = document.createElement('i');
  zoomInLabel.classList.add('bi', 'bi-plus');

  const zoomOutLabel = document.createElement('i');
  zoomOutLabel.classList.add('bi', 'bi-dash');

  const control = new Zoom({
    zoomInTipLabel: 'Zooma in',
    zoomInLabel: zoomInLabel,
    zoomOutTipLabel: 'Zooma ut',
    zoomOutLabel: zoomOutLabel,
    target: document.getElementById('zoom-control'),
  });

  control.element.classList.add('btn-group-vertical');
  for (const btn of control.element.getElementsByTagName('button')) {
    btn.classList.add('btn', 'btn-light');
  }
  map.addControl(control);
})();

/* zoom slider */
(function() {
  const control = new ZoomSlider({
    target: document.getElementById('zoom-control'),
  });
  control.element.classList.add('modal');
  for (const btn of control.element.getElementsByTagName('button')) {
    btn.classList.add('btn', 'btn-light');
  }
  map.addControl(control);
})();

/* scale line */
(function() {
  const size = map.getSize();
  const control = new ScaleLine({
    units: 'metric',
    minWidth: 150,
    maxWidth: size[1] < 350 ? size[1] - 50 : 350,
    target: container,
  });
  control.element.classList.add('modal', 'modal-content');
  map.addControl(control);
})();

const menu = document.getElementById('map-menu');
const TRAILING_ZEROES = /\.?0*$/;

/* "open in new tab" button */
if (window.location !== window.parent.location) {
  const div = document.createElement('div');
  menu.appendChild(div);
  div.classList.add('ol-unselectable', 'ol-control');

  const btn = document.createElement('button');
  div.appendChild(btn);
  btn.type = 'button';
  btn.title = 'Öppna karta i ny flik';
  btn.setAttribute('aria-label', btn.title);
  btn.setAttribute('aria-expanded', 'false');
  btn.classList.add('btn', 'btn-light');

  const i = document.createElement('i');
  btn.appendChild(i);
  i.classList.add('bi', 'bi-box-arrow-up-right');

  btn.onclick = function(event) {
    const coordinates = view.getCenter();
    const url = new URL(window.location.href);
    const searchParams = new URLSearchParams(url.hash.substring(1));
    searchParams.set('x', coordinates[0].toFixed(2).replace(TRAILING_ZEROES, ''));
    searchParams.set('y', coordinates[1].toFixed(2).replace(TRAILING_ZEROES, ''));
    searchParams.set('z', view.getZoom().toFixed(3).replace(TRAILING_ZEROES, ''));
    url.hash = '#' + searchParams.toString();
    return window.open(url.href, '_blank');
  };
}

/* layer selection button and legend */
if (window.location === window.parent.location) {
  const btn = (function() {
    const div = document.createElement('div');
    menu.appendChild(div);
    div.id = 'layer-selection-button';
    div.classList.add('ol-unselectable', 'ol-control');

    const btn = document.createElement('button');
    div.appendChild(btn);
    btn.type = 'button';
    btn.title = 'Lagerval';
    btn.setAttribute('aria-label', btn.title);
    btn.setAttribute('aria-expanded', 'false');
    btn.classList.add('btn', 'btn-light');

    const i = document.createElement('i');
    btn.appendChild(i);
    i.classList.add('bi', 'bi-stack');

    return btn;
  })();

  const btn2 = (function() {
    const div = document.createElement('div');
    menu.appendChild(div);
    div.id = 'map-legend-button';
    div.classList.add('ol-unselectable', 'ol-control');

    const btn = document.createElement('button');
    div.appendChild(btn);
    btn.type = 'button';
    btn.title = 'Teckenförklaring';
    btn.setAttribute('aria-label', btn.title);
    btn.setAttribute('aria-expanded', 'false');
    btn.classList.add('btn', 'btn-light');

    const i = document.createElement('i');
    btn.appendChild(i);
    i.classList.add('bi', 'bi-list-task');

    return btn;
  })();

  const panel = document.getElementById('layer-selection-panel');
  btn.onclick = function(event) {
    if (btn.getAttribute('aria-expanded') === 'true') {
      panel.setAttribute('aria-hidden', 'true');
      btn.setAttribute('aria-expanded', 'false');
      btn.classList.replace('btn-dark', 'btn-light');
    } else {
      if (btn2.getAttribute('aria-expanded') === 'true') {
        btn2.click();
      }
      panel.setAttribute('aria-hidden', 'false');
      btn.setAttribute('aria-expanded', 'true');
      btn.classList.replace('btn-light', 'btn-dark');
    }
  };

  const panel2 = document.getElementById('map-legend-panel');
  btn2.onclick = function(event) {
    if (btn2.getAttribute('aria-expanded') === 'true') {
      panel2.setAttribute('aria-hidden', 'true');
      btn2.setAttribute('aria-expanded', 'false');
      btn2.classList.replace('btn-dark', 'btn-light');
    } else {
      if (btn.getAttribute('aria-expanded') === 'true') {
        btn.click();
      }
      panel2.setAttribute('aria-hidden', 'false');
      btn2.setAttribute('aria-expanded', 'true');
      btn2.classList.replace('btn-light', 'btn-dark');
    }
  };
}

/* fullscreen control */
if (window.location === window.parent.location) {
  const label = document.createElement('i');
  label.classList.add('bi', 'bi-fullscreen');

  const labelActive = document.createElement('i');
  labelActive.classList.add('bi', 'bi-fullscreen-exit');

  const titleInactive = 'Helskärmsläge';
  const titleActive = 'Lämna helskärmsläge';
  const classInactive = 'btn-light';
  const classActive = 'btn-dark';

  const control = new FullScreen({
    label: label,
    labelActive: labelActive,
    tipLabel: titleInactive,
    keys: true,
    target: menu,
  })
  const btn = control.element.getElementsByTagName('button')[0];
  btn.classList.add('btn', classInactive);
  btn.setAttribute('aria-label', btn.title);
  map.addControl(control);

  control.addEventListener('enterfullscreen', function() {
    featureOverlaySource.clear(true);
    const popover = Popover.getInstance(popup);
    if (popover !== null) {
      /* dispose popover as entering fullscreen messes up its position */
      popover.dispose();
    }

    const btn = control.element.getElementsByTagName('button')[0];
    btn.classList.replace(classInactive, classActive);
    btn.title = titleActive;
    btn.setAttribute('aria-label', btn.title);

    const exp = document.getElementById('export-to-image');
    if (exp !== undefined) {
      /* hide export button in fullscreen mode as it exits it */
      exp.classList.add('d-none');
    }
  })
  control.addEventListener('leavefullscreen', function() {
    featureOverlaySource.clear(true);
    const popover = Popover.getInstance(popup);
    if (popover !== null) {
      /* dispose popover as is might overflow the viewport */
      popover.dispose();
    }

    const btn = control.element.getElementsByTagName('button')[0];
    btn.classList.replace(classActive, classInactive);
    btn.title = titleInactive;
    btn.setAttribute('aria-label', btn.title);

    const exp = document.getElementById('export-to-image');
    if (exp !== undefined) {
      exp.classList.remove('d-none');
    }
  })
}

/* export/download button */
if (window.location === window.parent.location) {
  const div = document.createElement('div');
  div.classList.add('ol-unselectable', 'ol-control');
  div.id = 'export-to-image';

  const btn = document.createElement('button');
  div.appendChild(btn);
  btn.classList.add('btn', 'btn-light');
  btn.type = 'button';
  btn.title = 'Ladda ner som en PNG-fil';
  btn.setAttribute('aria-label', btn.title);

  const i = document.createElement('i');
  btn.appendChild(i);
  i.classList.add('bi', 'bi-download');
  menu.appendChild(div);

  btn.onclick = function(event) {
    map.once('rendercomplete', function() {
      const canvas0 = document.createElement('canvas');
      const size = map.getSize();
      canvas0.width = size[0];
      canvas0.height = size[1];

      const context = canvas0.getContext('2d');
      map.getViewport().querySelectorAll('.ol-layer canvas, canvas.ol-layer').forEach(function(canvas) {
        if (canvas.width > 0) {
          const opacity = canvas.parentNode.style.opacity || canvas.style.opacity;
          context.globalAlpha = opacity === '' ? 1 : Number(opacity);
          context.drawImage(canvas, 0, 0);
        }
      });

      context.globalAlpha = 1;
      context.setTransform(1, 0, 0, 1, 0, 0);

      canvas0.toBlob(function(blob) {
        const a = document.createElement('a');
        a.download = 'karta.png';
        a.rel = 'noopener';
        a.href = URL.createObjectURL(blob);
        setTimeout(function() { URL.revokeObjectURL(a.href) }, 4E4); // 40s
        setTimeout(function() { a.click() }, 0);
      });
    });

    map.renderSync();
  };
}

/* info button */
(function() {
  const div = document.createElement('div');
  menu.appendChild(div);
  div.id = 'info-button';
  div.classList.add('ol-unselectable', 'ol-control');

  const btn = document.createElement('button');
  div.appendChild(btn);
  btn.type = 'button';
  btn.setAttribute('aria-expanded', 'false');
  btn.title = 'Visa information';
  btn.setAttribute('aria-label', btn.title);
  btn.classList.add('btn', 'btn-light');

  const i = document.createElement('i');
  btn.appendChild(i);
  i.classList.add('bi', 'bi-info-lg');

  const panel = document.getElementById('modal-info');
  const modal = new Modal(panel, {
    backdrop: false,
  });

  const backdrop = document.getElementById('modal-info-backdrop');
  backdrop.onclick = function(event) {
    modal.hide();
  };

  panel.addEventListener('show.bs.modal', function() {
    backdrop.classList.add('modal-backdrop', 'show');
    btn.setAttribute('aria-expanded', 'true');
    btn.classList.replace('btn-light', 'btn-dark');
  });
  panel.addEventListener('hidden.bs.modal', function() {
    btn.classList.replace('btn-dark', 'btn-light');
    btn.setAttribute('aria-expanded', 'false');
    backdrop.classList.remove('modal-backdrop', 'show');
  });

  btn.onclick = function(event) {
    modal.toggle();
  };
})();

/* we're all set, show the control container now */
container.setAttribute('aria-hidden', 'false');

view.on('change', function(event) {
  featureOverlaySource.clear(true);
  const popover = Popover.getInstance(popup);
  if (popover !== null) {
    popover.dispose();
  }

  const coordinates = view.getCenter();
  const searchParams = new URLSearchParams(location.hash.substring(1));
  searchParams.set('x', coordinates[0].toFixed(2).replace(TRAILING_ZEROES, ''));
  searchParams.set('y', coordinates[1].toFixed(2).replace(TRAILING_ZEROES, ''));
  searchParams.set('z', view.getZoom().toFixed(3).replace(TRAILING_ZEROES, ''));
  location.hash = '#' + searchParams.toString();
});


const layers = {
  mrr_appr_ec: {
    popoverTitle: 'Bearbetningskoncession \u2013 beviljad',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Ägare',              'Owner'],
      ['Area',               'Area'],
      ['Giltig från',        'Valid from'],
      ['Giltig till',        'Valid to'],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 22,
          fill: new Fill({
            color: [247, 170, 67, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [151, 173, 23, 1],
          }),
        });
      }),
  },
  mrr_appl_ec: {
    popoverTitle: 'Bearbetningskoncession \u2013 ansökt',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Sökande',            'Applicant'],
      ['Area',               'Area'],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 25,
          fill: new Fill({
            color: [247, 170, 67, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [197, 14, 31, 1],
            lineDash: width >= 1.5 ? [2 * width] : undefined,
          }),
        });
      }),
  },
  mrr_appr_met: {
    popoverTitle: 'Undersökningstillstånd, metaller och industrimineral \u2013 beviljad',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Ägare',              'Owner'],
      ['Licence id',         'Licence id', { classes: ['feature-attr-mrr-license-id'] }],
      ['Area',               'Area'],
      ['Giltig från',        'Valid from'],
      ['Giltig till',        'Valid to'],
      ['Diary nr',           'Diary nr', { classes: ['feature-attr-dnr'] }],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 24,
          fill: new Fill({
            color: [0, 0, 0, Math.max((.2-.4)/4 * z + .4, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [151, 173, 23, 1],
          }),
        });
      }),
  },
  mrr_appl_met: {
    popoverTitle: 'Undersökningstillstånd, metaller och industrimineral \u2013 ansökt',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Sökande',            'Applicant'],
      ['Area',               'Area'],
      ['Ansökningsdatum',    'Application date'],
      ['Diary nr',           'Diary nr', { classes: ['feature-attr-dnr'] }],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 26,
          fill: new Fill({
            color: [0, 0, 0, Math.max((.2-.4)/4 * z + .4, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [197, 14, 31, 1],
            lineDash: width >= 1.5 ? [2 * width] : undefined,
          }),
        });
      }),
  },
  mrr_appr_ogd: {
    popoverTitle: 'Undersökningstillstånd, olja, gas och diamant \u2013 beviljad',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Ägare',              'Owner'],
      ['Licence id',         'Licence id', { classes: ['feature-attr-mrr-license-id'] }],
      ['Area',               'Area'],
      ['Giltig från',        'Valid from'],
      ['Giltig till',        'Valid to'],
      ['Diary nr',           'Diary nr', { classes: ['feature-attr-dnr'] }],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 24,
          fill: new Fill({
            color: [30, 55, 87, Math.max((.2-.4)/4 * z + .4, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [151, 173, 23, 1],
          }),
        });
      }),
  },
  mrr_appl_ogd: {
    popoverTitle: 'Undersökningstillstånd, olja, gas och diamant \u2013 ansökt',
    popover: [
      ['Namn',               'Name'],
      ['Koncessionsmineral', 'Mineral'],
      ['Sökande',            'Applicant'],
      ['Area',               'Area'],
      ['Ansökningsdatum',    'Application date'],
      ['Diary nr',           'Diary nr', { classes: ['feature-attr-dnr'] }],
      ['Kommun',             'Municipality'],
      ['Län',                'County'],
      ['Senast uppdaterad',  'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 26,
          fill: new Fill({
            color: [30, 55, 87, Math.max((.2-.4)/4 * z + .4, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [197, 14, 31, 1],
            lineDash: width >= 1.5 ? [2 * width] : undefined,
          }),
        });
      }),
  },
  mrr_appr_dl: {
    popoverTitle: 'Markanvisning till koncession',
    popover: [
      ['Namn',              'Name'],
      ['Area',              'Area'],
      ['Kommun',            'Municipality'],
      ['Län',               'County'],
      ['Senast uppdaterad', 'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 20,
          fill: new Fill({
            color: [228, 53, 45, Math.max((.2-1)/6 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [151, 173, 23, 1],
          }),
        });
      }),
  },
  mrr_appr_pc: {
    popoverTitle: 'Gällande torvkoncession',
    popover: [
      ['Namn',              'Name'],
      ['Ägare',             'Owner'],
      ['Area',              'Area'],
      ['Giltig från',       'Valid from'],
      ['Giltig till',       'Valid to'],
      ['Kommun',            'Municipality'],
      ['Län',               'County'],
      ['Senast uppdaterad', 'Last updated'],
    ],
    style: [0, .1, .5, .5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 21,
          fill: new Fill({
            color: [65, 40, 27, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [151, 173, 23, 1],
          }),
        });
      }),
  },

  svk_lines: {
    popoverTitle: 'Kraftledning (befintlig)',
    popover: [
      ['Förläggn', 'FÖRLÄGGN'],
      ['Spänning', 'SPÄNNING', { unit: 'kV' }],
    ],
    style: [1, 1.5, 2, 2, 2, 2, 3, 4, 5, 6, 8, 10].map(function(width) {
        return new Style({
          zIndex: 52,
          stroke: new Stroke({
            color: 'black',
            width: width,
          }),
        });
      }),
  },
  svk_pylons: {
    style: [undefined, undefined, undefined, undefined, undefined]
      .concat([3, 4, 5, 6, 8, 10, 15].map(function(radius) {
          return new Style({
            zIndex: 51,
            image: new CircleStyle({
              radius: radius,
              fill: new Fill({
                color: 'black',
              }),
            }),
          });
      })),
  },
  svk_planned: {
    popoverTitle: 'Transmissionsnätsprojekt',
    popover: [
      ['Projektnamn', 'name'],
      ['Spänning', 'voltage', { unit: 'kV' }],
      ['Länk', 'url', { fn: function(v) {
        const a = document.createElement('a');
        a.href = v;
        a.target = '_blank';
        const i = document.createElement('i');
        i.classList.add('bi', 'bi-box-arrow-up-right');
        a.appendChild(i);
        return a;
      }}],
    ],
    style: [1, 1.5, 2, 2, 2, 2, 3, 4, 5, 6, 8, 10].map(function(width) {
        return new Style({
          zIndex: 53,
          stroke: new Stroke({
            color: 'black',
            width: width,
            lineDash: [4 * width],
          }),
        });
      }),
  },
  svk_stations: {
    style: [3, 4, 5, 6, 7, 8.5, 10].map(function(radius) {
        return new Style({
          zIndex: 50,
          image: new RegularShape({
            radius: radius,
            points: 4,
            angle: Math.PI/4,
            fill: new Fill({
              color: 'black',
            }),
          }),
        });
      })
      .concat([.5, 1, 1.5, 2, 2].map(function(width) {
        return new Style({
          zIndex: 50,
          fill: new Fill({
            color: 'rgba(128, 128, 128, .7)',
          }),
          stroke: new Stroke({
            width: width,
            color: 'rgb(0, 0, 0)',
          }),
        });
      })),
  },

  vbk_area_current: {
    popoverTitle: 'Projekteringsområde för vindbruk',
    popover: [
      ['Projektnamn', 'PROJNAMN'],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Aktuella verk', 'ANTALVERK'],
      ['Antal ej koordinatsatta verk', 'AntalejXY', { fn: (v) => v || 0 }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Planerad byggstart', 'PBYGGSTART'],
      ['Planerat drifttagande', 'PDRIFT'],
      ['Andringsansokan', 'Andringsansokan'],
      ['Under Byggnation', 'UnderByggnation'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNR', { classes: ['feature-orgnr'] }],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Senast uppdaterat', 'ArendeStatusUppdaterat'],
    ],
    style: [.5, 1, 1.5, 1.5, 2, 2, 2.5, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 10,
          fill: new Fill({
            color: [168, 198, 223, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [56, 96, 130, 1],
          }),
        });
      }),
  },
  vbk_area_notcurrent: {
    popoverTitle: 'Projekteringsområde för vindbruk \u2013 ej aktuell',
    popover: [
      ['Projektnamn', 'PROJNAMN'],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Aktuella verk', 'ANTALVERK'],
      ['Antal ej koordinatsatta verk', 'AntalejXY', { fn: (v) => v || 0 }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Planerad byggstart', 'PBYGGSTART'],
      ['Planerat drifttagande', 'PDRIFT'],
      ['Andringsansokan', 'Andringsansokan'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNR', { classes: ['feature-orgnr'] }],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Senast uppdaterat', 'ArendeStatusUppdaterat'],
    ],
    style: [.5, 1, 1.5, 1.5, 2, 2, 2.5, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        return new Style({
          zIndex: 10,
          fill: new Fill({
            color: [222, 163, 199, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [148, 55, 112, 1],
            lineDash: width >= 1.5 ? [2 * width] : undefined,
          }),
        });
      }),
  },
  vbk_station_completed: {
    popoverTitle: 'Vindkraftverk \u2013 uppfört',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Uppförandedatum', 'UPPFORT'],
      ['Miljöbalken tillstånd tidsbegränsning', 'MB_Tillstand_TIDSBEGRANS_DAT'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-completed.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_processed: {
    popoverTitle: 'Vindkraftverk \u2013 handlagt',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-processed.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_approved: {
    popoverTitle: 'Vindkraftverk \u2013 beviljat',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Miljöbalken tillstånd tidsbegränsning', 'MB_Tillstand_TIDSBEGRANS_DAT'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-approved.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_revoked: {
    popoverTitle: 'Vindkraftverk \u2013 inte längre aktuell/återkallat',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Miljöbalken tillstånd tidsbegränsning', 'MB_Tillstand_TIDSBEGRANS_DAT'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-revoked.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_rejected: {
    popoverTitle: 'Vindkraftverk \u2013 avslagit/nekat',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Miljöbalken tillstånd tidsbegränsning', 'MB_Tillstand_TIDSBEGRANS_DAT'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-rejected.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_dismounted: {
    popoverTitle: 'Vindkraftverk \u2013 nedmonterat',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Uppförandedatum', 'UPPFORT'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-dismounted.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },
  vbk_station_appealed: {
    popoverTitle: 'Vindkraftverk \u2013 överklagat',
    popover: [
      ['Verk-ID', 'VERKID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMRID', { classes: ['feature-objid'] }],
      ['Projektnamn', 'PROJNAMN'],
      ['Status', 'STATUS'],
      ['Handlingstyp', 'HANDLINGSTYP'],
      ['Totalhöjd', 'TOTALHOJD', { unit: 'm' }],
      ['Navhöjd', 'NAVHOJD', { unit: 'm' }],
      ['Rotordiameter', 'ROTDIAMETER', { unit: 'm' }],
      ['Maxeffekt', 'MAXEFFEKT', { unit: 'MW' }],
      ['Beräknad årsproduktion', 'CALPROD', { unit: 'GWh' }],
      ['Fabrikat', 'FABRIKAT'],
      ['Modell', 'MODELL'],
      ['Organisationsnamn', 'ORGNAMN'],
      ['Organisationsnummer', 'ORGNMR', { classes: ['feature-orgnr'] }],
      ['Placering', 'PLACERING'],
      ['Kommun', 'KOMNAMN'],
      ['Län', 'LANSNAMN'],
      ['Elområde', 'EL_NAMN'],
      ['Datum för senaste uppdatering av verk', 'SenasteUppdatering'],
    ],
    style: [undefined, undefined, undefined, undefined, .125, .125, .25, .5, 1, 2, 4, 8].map(function(scale) {
        return scale === undefined ? undefined : new Style({
          zIndex: 99,
          image: new Icon({
            src: '/assets/icons/wind-turbine-appealed.svg',
            declutter: 'none',
            scale: scale,
          }),
        });
      }),
  },

  /* Documentation at
   * https://www.skogsstyrelsen.se/globalassets/sjalvservice/karttjanster/geodatatjanster/produktbeskrivningar/utforda-avverkningar---produktbeskrivning.pdf
   * */
  sks_clearcut_comp: {
    popoverTitle: 'Utförd avverkning',
    popover: [
      ['Ärendebeteckning', 'Beteckn', { classes: ['feature-objid'] }],
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Registeringsår', 'ArendeAr'],
      ['Skogstyp', 'Skogstyp'],
      ['Areal anmält', 'AnmaldHa', { unit: 'ha' }],
      ['Areal naturlig föryngring', 'NatforHa', { unit: 'ha', fn: (v) => v === 0 ? '' : v }],
      ['Areal plantering', 'SkogsodlHa', { unit: 'ha', fn: (v) => v === 0 ? '' : v }],
      ['Avverkningstyp', 'Avverktyp'],
      ['Datum för avverkning', 'Avvdatum'],
      ['Ursprung för datum för avverkning', 'KallaDatum'],
      ['Ursprung för areal avverkning', 'KallaAreal'],
      ['Kommun', 'Kommun'],
      ['Län', 'Lan'],
      ['Areal för ytan', 'Arealha', { unit: 'ha' }],
    ],
    style: [0, 0, 0, 0, 0, .5, .75, 1, 1, 1, 1, 1].map(function(width, z) {
        return new Style({
          zIndex: 10,
          fill: new Fill({
            color: [255, 102, 102, Math.max((.2-1)/8 * z + 1, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [204, 0, 0, 1],
          }),
        });
      }),
  },
  /* Documentation at
   * https://www.skogsstyrelsen.se/globalassets/sjalvservice/karttjanster/geodatatjanster/produktbeskrivningar/yttre-granser-for-avverkningsanmalda-omraden---produktbeskrivning.pdf
   * */
  sks_clearcut_appl: {
    popoverTitle: 'Avverkningsanmälansområde',
    popover: [
      ['Ärendebeteckning', 'Beteckn', { classes: ['feature-objid'] }],
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Inkom datum', 'Inkomdatum'],
      ['Registeringsår', 'ArendeAr'],
      ['Skogstyp', 'Skogstyp'],
      ['Areal anmält', 'AnmaldHa', { unit: 'ha' }],
      ['Areal naturlig föryngring', 'NatforHa', { unit: 'ha', fn: (v) => v === 0 ? '' : v }],
      ['Areal plantering', 'SkogsodlHa', { unit: 'ha', fn: (v) => v === 0 ? '' : v }],
      ['Avverkningssäsong', 'AvvSasong'],
      ['Avverkningstyp', 'Avverktyp'],
      ['Kommun', 'Kommun'],
      ['Län', 'Lan'],
      ['Ärendestatus', 'ArendeStat'],
      ['Avverkad areal', 'AvvHa', { unit: 'ha' }],
    ],
    style: [0, 0, 0, 0, 0, .5, .75, 1, 1, 1, 1, 1].map(function(width, z) {
        return new Style({
          zIndex: 10,
          fill: (width === undefined || width === 0) ?
            new Fill({ color: [255, 102, 102, Math.max((.2-1)/8 * z + 1, 0)*.75] }) :
            (function() {
              const patternCanvas = document.createElement('canvas');
              const patternContext = patternCanvas.getContext('2d');
              const slope = 45 * Math.PI/180;
              const spacing = z < 10 ? z*2 : 40;
              const len = Math.hypot(1, slope);
              const w = patternCanvas.width = Math.round(1/len + spacing)
              const h = patternCanvas.height = Math.round(slope/len + spacing * slope);

              patternContext.fillStyle = 'rgba(255, 102, 102, .1)';
              patternContext.fillRect(0, 0, patternCanvas.width, patternCanvas.height);
              patternContext.strokeStyle = 'rgba(204, 0, 0, 1)';
              patternContext.lineWidth = Math.max(1, width/2);
              patternContext.beginPath();
              patternContext.moveTo(0, h);
              patternContext.lineTo(w, 0);
              patternContext.moveTo(-w, h);
              patternContext.lineTo(w, -h);
              patternContext.moveTo(0, 2*h);
              patternContext.lineTo(2*w, 0);
              patternContext.stroke();

              const canvas = document.createElement('canvas');
              const context = canvas.getContext('2d');
              return new Fill({ color: context.createPattern(patternCanvas, 'repeat') });
            })(),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [204, 0, 0, 1],
            lineDash: width >= 1.5 ? [2 * width] : undefined,
          }),
        });
      }),
  },

  st_renbete: {
    popoverTitle: 'Samebyarnas betesområde',
    popover: [
      ['Sameby', 'NAMN'],
      ['Samebys typ', 'SAMEBY_TYP'],
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Sameby-ID', 'SAMEBY_ID', { classes: ['feature-objid'] }],
      ['By-ID', 'BY_ID', { classes: ['feature-objid'] }],
      ['Signatur', 'SIGNATUR'],
      ['Aktualitet', 'AKTUALITET'],
    ],
    style: [1, 1.5, 2, 3, 3.5, 4, 5, 5, 6, 7, 8, 10].map(function(width, z) {
        return new Style({
          zIndex: 4,
          fill: new Fill({
            /* transparent fill so clicking the inside of the polygon triggers a popover */
            /* XXX could also use a custom renderer but that doesn't seem to work */
            color: [0, 0, 0, 0],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [179, 153, 102, 1],
          }),
        });
      }),
  },
  st_flyttled: {
    popoverTitle: 'Samebyarnas markanvändningsredovisning \u2013 flyttled',
    popover: [
      ['Sameby #1', 'SAMEBY1'],
      ['Sameby #2', 'SAMEBY2'],
      ['Sameby #3', 'SAMEBY3'],
      ['Beskrivning', 'BESKRIVNIN'],
      ['Årstid', 'ARSTID'],
      ['Sameby #1 Nr', 'BYNR1', { classes: ['feature-objid'], fn: (v) => v === 0 ? '' : v }],
      ['Sameby #2 Nr', 'BYNR2', { classes: ['feature-objid'], fn: (v) => v === 0 ? '' : v }],
      ['Sameby #3 Nr', 'BYNR3', { classes: ['feature-objid'], fn: (v) => v === 0 ? '' : v }],
      ['Led-ID', 'LED_ID', { classes: ['feature-objid'], fn: (v) => v === 0 ? '' : v }],
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Riksintresse', 'RIKSINTR'],
      ['Fast led', 'FAST_LED'],
      ['Aktualitet', 'AKTUALITET'],
      ['Signatur', 'SIGNATUR'],
      ['Globalt ID', 'GlobalID', { classes: ['feature-objid'] }],
    ],
    style: [.75, 1, 1.5, 2, 3, 4, 5, 5, 6, 7, 8, 10].map(function(width, z) {
        return new Style({
          zIndex: 7,
          stroke: new Stroke({
            width: 2*width,
            color: [119, 99, 59, 1],
            lineDash: [4 * width],
          }),
        });
      }),
  },
  st_riks_ren: {
    popoverTitle: 'Riksintresse rennäring',
    popover: [
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Lagrum', 'LAGRUM'],
      ['Aktualitet', 'AKTUALITET'],
      ['Signatur', 'SIGNATUR'],
      ['Globalt ID', 'GlobalID', { classes: ['feature-objid'] }],
    ],
    style: [.5, 1, 1.5, 1.5, 2, 2, 2.5, 2.5, 3, 3.5, 4, 5].map(function(width, z) {
        const patternCanvas = document.createElement('canvas');
        const patternContext = patternCanvas.getContext('2d');
        patternCanvas.width = z < 4 ? 4 : z <= 5 ? 8 : Math.pow(2, Math.round(Math.log2(width) + 3));
        patternCanvas.height = patternCanvas.width;
        patternContext.fillStyle = 'transparent';
        patternContext.strokeStyle = 'rgba(179, 153, 102, 1)';
        patternContext.lineWidth = Math.max(1, width/2);
        patternContext.beginPath();
        patternContext.moveTo(0, 0);
        patternContext.lineTo(patternCanvas.width, 0);
        patternContext.stroke();

        const canvas = document.createElement('canvas');
        const context = canvas.getContext('2d');
        return new Style({
          zIndex: 6,
          fill: new Fill({
            color: context.createPattern(patternCanvas, 'repeat'),
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [179, 153, 102, 1],
          }),
        });
      }),
  },
  st_riks_ren_core: {
    popoverTitle: '(Kärn)områden av riksintresse rennäring',
    popover: [
      ['Objekt-ID', 'OBJECTID', { classes: ['feature-objid'] }],
      ['Områdes-ID', 'OMR_NR', { classes: ['feature-objid'] }],
      ['Länk', 'LANK'],
      ['Årets runt', 'ARET_RUNT'],
      ['Sameby', 'SAMEBY'],
      ['Ansvarig', 'ANSVARIG'],
      ['Aktualitet', 'AKTUALITET'],
      ['Signatur', 'SIGNATUR'],
      ['Globalt ID', 'GlobalID', { classes: ['feature-objid'] }],
      ['Area', 'AREA_HA', { unit: 'ha' }],
      ['Länskod', 'LANSKOD'],
    ],
    style: [.5, .5, 1, 1, 1, 1.5, 1.5, 1.5, 2, 2, 2, 2].map(function(width, z) {
        return new Style({
          zIndex: 5,
          fill: new Fill({
            color: [203, 190, 163, Math.max((.3-.5)/8 * z + .5, 0)],
          }),
          stroke: width === 0 ? undefined : new Stroke({
            width: width,
            color: [179, 153, 102, 1],
          }),
        });
      }),
  },

  /* Documentation at
   * https://www.smhi.se/polopoly_fs/1.34541!/dammprod%202013_3%2C%20beskrivning%2C%20SVAR2012_2.pdf
   * */
  smhi_dam: {
    popoverTitle: 'Damm',
    popover: [
      ['Dammenhetens namn', 'dnamn'],
      ['Dammanläggningens namn', 'namn'],
      ['Länsnr', 'lst_objid', { classes: ['feature-objid'] }],
      ['Status', 'status', { fn: (v) => v === 0 ? '' : v === 1 ? 'Befintlig damm' : v === 2 ? 'Fd. damm' : v }],
      ['Regleringstyp', 'regl_typ', { fn: (v) => v === 0 ? '' : v }],
      ['Byggår', 'byggar', { fn: (v) => v === 0 ? '' : v }],
      ['Dammhöjd', 'dammhojd', { unit: 'm', fn: (v) => v === 0 ? '' : v }],
      ['Krönlängd', 'kron', { unit: 'm', fn: (v) => v === 0 ? '' : v }],
      ['Fiskväg', 'fiskvag', { fn: (v) =>
        v === 0 ? '' :
        v === 1 ? 'Bassängtrappa' :
        v === 2 ? 'Denilränna' :
        v === 3 ? 'Slitsränna' :
        v === 4 ? 'Omlöp' :
        v === 5 ? 'Inlöp' :
        v === 6 ? 'Ålledare' :
        v === 7 ? 'Smoltränna' :
        v === 8 ? 'Okänd typ' :
        v === 9 ? 'Ingen' :
        v === 10 ? 'Annan' :
        v }],
      ['Huvudavrinningsområdesnummer', 'haro', { classes: ['feature-objid'] } ],
      ['Vattendistrikt', 'RBD', { classes: ['feature-objid'] } ],
      ['Verksamhet', 'verksmht', { fn: (v) =>
        v === 0 ? '' :
        v === 1 ? 'Kraftproduktion' :
        v === 2 ? 'Industri' :
        v === 3 ? 'Sjöfart' :
        v === 4 ? 'Invallning' :
        v === 5 ? 'Vattenförsörjning' :
        v === 6 ? 'Spegeldamm' :
        v === 7 ? 'Historisk' :
        v === 8 ? 'Övrigt' :
        v }],
      ['Högsta dämningsgräns', 'dg', { unit: 'm', fn: (v) => v === 0 ? '' : v }],
      ['Lägsta sänkningsgräns', 'sg', { unit: 'm', fn: (v) => v === 0 ? '' : v }],
      ['Magasinsyta', 'my', { unit: 'km²', fn: (v) => v === 0 ? '' : v }],
      ['Reglerbar volym', 'my', { unit: 'Mm³', fn: (v) => v === 0 ? '' : v }],
      ['Kommentar', 'kommentar'],
      ['Damm-ID', 'dammid', { classes: ['feature-objid'] }],
    ],
    style: [2, 3, 4, 4, 4, 6, 8, 8, 8, 10, 16, 32].map(function(width) {
        return new Style({
          zIndex: 59,
          image: new CircleStyle({
            radius: width,
            fill: new Fill({
              color: 'rgb(219, 30, 42)',
            }),
            stroke: new Stroke({
              width: Math.log2(width) * 2/5,
              color: 'rgb(128, 17, 25)',
            }),
          }),
        });
      }),
  },

  gigafactories: {
    popoverTitle: 'Stor industrisatsning',
    popover: [
      ['Namn', 'name'],
      ['Länk', 'url', { fn: function(v) {
        const a = document.createElement('a');
        a.href = v;
        a.target = '_blank';
        const i = document.createElement('i');
        i.classList.add('bi', 'bi-box-arrow-up-right');
        a.appendChild(i);
        return a;
      }}],
    ],
    style: [4, 6, 7, 8, 10, 12].map(function(width) {
        return new Style({
          zIndex: 60,
          image: new CircleStyle({
            radius: width,
            fill: new Fill({
              color: 'rgb(152, 78, 163)',
            }),
            stroke: new Stroke({
              width: Math.log2(width) * 2/5,
              color: 'rgb(119, 61, 128)',
            }),
          }),
        });
      })
      .concat([1.5, 2, 2, 2, 2, 2].map(function(width) {
        return new Style({
          zIndex: 58,
          fill: new Fill({
            color: 'rgba(152, 78, 163, .4)',
          }),
          stroke: new Stroke({
            width: width,
            color: 'rgb(119, 61, 128)',
          }),
        });
      })),
  }
};

const layerHierarchy = [
  {
    text: 'Transmissionsnät för el',
    children: [
      {
        text: 'Kraftledningar (befintliga)',
        layer: ['svk_lines', 'svk_pylons'],
      },
      {
        text: 'Stationer',
        layer: 'svk_stations',
      },
      {
        text: 'Transmissionsnätsprojekt ',
        layer: 'svk_planned',
      },
    ],
  },
  {
    text: 'Stora industrisatsningar',
    layer: 'gigafactories',
  },
  {
    text: 'Dammar',
    layer: 'smhi_dam',
  },
  {
    text: 'Mineralrättigheter',
    children: [
      {
        text: 'Bearbetningskoncessioner',
        children: [
          {
            text: 'Beviljad',
            layer: 'mrr_appr_ec',
          },
          {
            text: 'Ansökt',
            layer: 'mrr_appl_ec',
          },
        ],
      },
      {
        text: 'Undersökningstillstånd, olja, gas och diamant',
        children: [
          {
            text: 'Beviljad',
            layer: 'mrr_appr_ogd',
          },
          {
            text: 'Ansökt',
            layer: 'mrr_appl_ogd',
          },
        ],
      },
      {
        text: 'Undersökningstillstånd, metaller och industrimineral',
        children: [
          {
            text: 'Beviljad',
            layer: 'mrr_appr_met',
          },
          {
            text: 'Ansökt',
            layer: 'mrr_appl_met',
          },
        ],
      },
      {
        text: 'Markanvisningar till koncession',
        layer: 'mrr_appr_dl',
      },
      {
        text: 'Gällande torvkoncessioner',
        layer: 'mrr_appr_pc',
      },
    ],
  },
  {
    text: 'Vindbruk',
    children: [
      {
        text: 'Projekteringsområden',
        children: [
          {
            text: 'Aktuella',
            layer: 'vbk_area_current',
          },
          {
            text: 'Ej aktuella',
            layer: 'vbk_area_notcurrent',
          },
        ],
      },
      {
        text: 'Vindkraftverk',
        children: [
          {
            text: 'Uppförda',
            layer: 'vbk_station_completed',
          },
          {
            text: 'Handläggs',
            layer: 'vbk_station_processed',
          },
          {
            text: 'Beviljade',
            layer: 'vbk_station_approved',
          },
          {
            text: 'Inte längre aktuella/återkallade',
            layer: 'vbk_station_revoked',
          },
          {
            text: 'Avslagna/nekad',
            layer: 'vbk_station_rejected',
          },
          {
            text: 'Nedmonterade',
            layer: 'vbk_station_dismounted',
          },
          {
            text: 'Överklagade',
            layer: 'vbk_station_appealed',
          },
        ],
      },
    ]
  },
  {
    text: 'Skogsbruk',
    children: [
      {
        text: 'Uppförda (sedan 2000)',
        layer: 'sks_clearcut_comp',
      },
      {
        text: 'Anmälda',
        layer: 'sks_clearcut_appl',
      },
    ]
  },
  {
    /* Definitions at
     * https://ext-dokument.lansstyrelsen.se/Gemensamt/Geodata/Datadistribution/Information,%20Skiktf%C3%B6rteckning%20och%20f%C3%B6rklaringar.pdf */
    text: 'Rennäringen',
    children: [
      {
        text: 'Betesområden',
        layer: 'st_renbete',
      },
      {
        text: 'Flyttled',
        layer: 'st_flyttled',
      },
      {
        text: 'Riksintressen',
        layer: 'st_riks_ren',
      },
      {
        text: '(Kärn)områden av riksintresse',
        layer: 'st_riks_ren_core',
      },
    ]
  }
];

const vectorSource = new VectorTile({
  url: '/tiles/a/{z}/{x}/{y}.pbf',
  format: new MVT(),
  projection: projection,
  wrapX: false,
  transition: 0,
  tileGrid: createXYZ({
    extent: extent,
    tileSize: 1024,
    maxResolution: 1024, /* = 1048576/1024 */
    minZoom: 0,
    maxZoom: 9,
  }),
});
const vectorSource2 = new VectorTile({
  url: '/tiles/b/{z}/{x}/{y}.pbf',
  format: new MVT(),
  projection: projection,
  wrapX: false,
  transition: 0,
  tileGrid: createXYZ({
    extent: extent,
    tileSize: 1024,
    maxResolution: 1024, /* = 1048576/1024 */
    minZoom: 0,
    maxZoom: 9,
  }),
});

const styles = (function() {
  const searchParams = new URLSearchParams(location.hash.substring(1));
  const layersParams = searchParams.has('layers') ? searchParams.get('layers').split(' ') : [];
  return Object.keys(layers).reduce(function(result, key) {
    if (layersParams.includes(key)) {
      result[key] = layers[key].style;
    }
    return result;
  }, {});
})();

const vectorLayer = new VectorTileLayer({
  source: vectorSource,
  /* XXX switch to 'hybrid' if there are perf issues; but that seems to
   * put lines above points regardless of their respective z-index */
  renderMode: 'hybrid',
  declutter: false,
  visible: false,
  style: function(feature, resolution) {
    const style = styles[feature.getProperties().layer];
    if (!Array.isArray(style)) {
      return style;
    } else {
      const maxi = style.length - 1;
      const z = 10 /* Math.log2(maxResolution) */ - Math.log2(resolution);
      /* use Math.floor() as VectorTile.js calls getZForResolution(resolution, 1) */
      const i = z <= 0 ? 0 : z >= maxi ? maxi : Math.floor(z);
      // console.log(`resolution=${resolution}, z=${z}, i=${i}`);
      return style[i];
    }
  },
});
map.addLayer(vectorLayer);

const vectorLayer2 = new VectorTileLayer({
  source: vectorSource2,
  renderMode: 'hybrid',
  declutter: false,
  visible: false,
  style: function(feature, resolution) {
    const style = styles[feature.getProperties().layer];
    if (!Array.isArray(style)) {
      return style;
    } else {
      const maxi = style.length - 1;
      const z = 10 /* Math.log2(maxResolution) */ - Math.log2(resolution);
      /* use Math.floor() as VectorTile.js calls getZForResolution(resolution, 1) */
      const i = z <= 0 ? 0 : z >= maxi ? maxi : Math.floor(z);
      // console.log(`resolution=${resolution}, z=${z}, i=${i}`);
      return style[i];
    }
  },
});
map.addLayer(vectorLayer2);

/* layer selection panel */
(function() {
  const modal = document.getElementById('layer-selection-panel');
  modal.classList.add('modal');
  modal.setAttribute('role', 'dialog');
  modal.setAttribute('aria-hidden', 'true');

  const content = document.createElement('div');
  modal.appendChild(content);
  content.classList.add('modal-content');

  const body = document.createElement('div');
  content.appendChild(body);
  body.classList.add('modal-body');

  const accordion = document.createElement('div');
  body.appendChild(accordion);
  accordion.id = 'layer-selection-accordion';
  accordion.classList.add('accordion', 'accordion-flush');

  (function collectLayers(list) {
    list.forEach(function(elem) {
      elem._layers = elem.layer === undefined ? []
                   : Array.isArray(elem.layer) ? elem.layer
                   : [elem.layer];
      if (elem.children !== undefined && elem.children.length > 0) {
        collectLayers(elem.children);
        elem.children.forEach(function(child) {
          child._layers.forEach((l) => elem._layers.push(l));
        });
      }
    });
  })(layerHierarchy);

  const setIndeterminateAndChecked = function(list) {
    return list.forEach(function(elem) {
      const layerStyles = elem._layers.map((lyr) => styles[lyr] !== undefined);
      elem._input.indeterminate = elem._layers.length <= 1 ? false
                                : layerStyles.slice(1).some((v) => v !== layerStyles[0]);
      if (!elem._input.indeterminate) {
        /* keep checked value if indeterminate */
        elem._input.checked = layerStyles.every((v) => v);
      }
      if (elem.children !== undefined && elem.children.length > 0) {
        setIndeterminateAndChecked(elem.children);
      }
    });
  };
  /* TODO refactor */
  const layerList1 = Object.keys(layers).filter((l) => !l.startsWith('sks_') && !l.startsWith('st_'));
  const layerList2 = Object.keys(layers).filter((l) =>  l.startsWith('sks_') ||  l.startsWith('st_'));
  const fixLayerVisibility = function() {
    vectorLayer .setVisible(layerList1.some((lyr) => styles[lyr] !== undefined));
    vectorLayer2.setVisible(layerList2.some((lyr) => styles[lyr] !== undefined));
  };
  const onClickFunction = function(layerList, event) {
    const searchParams = new URLSearchParams(location.hash.substring(1));
    let layersParams = searchParams.get('layers') || '';
    layersParams = layersParams.match(/^\s*$/) ? [] : layersParams.split(' ');
    if (event.target.checked) {
      layerList.forEach(function(lyr) {
        styles[lyr] = layers[lyr].style;
        if (!layersParams.includes(lyr)) {
          layersParams.push(lyr);
        }
      });
    } else {
      layerList.forEach(function(lyr) {
        delete styles[lyr];
      });
      layersParams = layersParams.filter((lyr) => !layerList.includes(lyr));
    }
    setIndeterminateAndChecked(layerHierarchy);
    fixLayerVisibility();
    vectorSource.changed();
    vectorSource2.changed();
    searchParams.set('layers', layersParams.join(' '));
    location.hash = '#' + searchParams.toString();
  };

  let layerId = 0;
  const addAccordionGroup = function(parentNode, children) {
    const ul = document.createElement('ul');
    parentNode.appendChild(ul);
    ul.classList.add('list-group', 'list-group-flush');

    children.forEach(function(child) {
      const li = document.createElement('li');
      ul.appendChild(li);
      li.classList.add('list-group-item');

      const div = document.createElement('div');
      li.appendChild(div);
      div.classList.add('d-inline-flex');

      const input = child._input = document.createElement('input');
      div.appendChild(input);
      input.classList.add('form-check-input');
      input.type = 'checkbox';
      input.id = 'layer' + layerId++;

      const label = document.createElement('label');
      div.appendChild(label);
      label.classList.add('form-check-label');
      label.setAttribute('for', input.id);

      const textNode = document.createTextNode(child.text);
      label.appendChild(textNode);

      if (child.children !== undefined && child.children.length > 0) {
        addAccordionGroup(li, child.children);
      }

      input.onclick = function(event) {
        return onClickFunction(child._layers, event);
      };
    });
  };
  layerHierarchy.forEach(function(x, idx) {
    const item = document.createElement('div');
    accordion.appendChild(item);
    item.classList.add('accordion-item');

    const header = document.createElement('div');
    item.appendChild(header);
    header.classList.add('accordion-header');

    const btn = document.createElement('button');
    header.appendChild(btn);

    const collapse = document.createElement('div');
    item.appendChild(collapse);
    collapse.id = 'accordion-collapse-' + idx;
    collapse.classList.add('accordion-collapse', 'collapse');
    /* never expand more than accordion at a time */
    collapse.setAttribute('data-bs-parent', '#' + accordion.id);

    btn.type = 'button';
    btn.setAttribute('data-bs-toggle', 'collapse');
    btn.setAttribute('data-bs-target', '#' + collapse.id);
    btn.setAttribute('aria-expanded', 'false');
    btn.setAttribute('aria-controls', collapse.id);
    btn.classList.add('accordion-button', 'collapsed');

    const span0 = document.createElement('span');
    btn.appendChild(span0);
    span0.classList.add('form-check');
    span0.setAttribute('data-bs-toggle', 'collapse');
    span0.setAttribute('data-bs-target', '');

    const input0 = x._input = document.createElement('input');
    span0.appendChild(input0);
    input0.classList.add('form-check-input');
    input0.type = 'checkbox';
    input0.id = 'layer' + layerId++;

    const label0 = document.createElement('label');
    span0.appendChild(label0);
    label0.classList.add('form-check-label');
    label0.setAttribute('for', input0.id);

    const text0 = document.createTextNode(x.text);
    label0.appendChild(text0);

    if (x.children === undefined || x.children.length === 0) {
      item.replaceChild(span0, header);
    } else {
      const body = document.createElement('div');
      collapse.appendChild(body);
      body.classList.add('accordion-body');

      addAccordionGroup(body, x.children);
    }

    input0.onclick = function(event) {
      return onClickFunction(x._layers, event);
    };
  });
  setIndeterminateAndChecked(layerHierarchy);
  fixLayerVisibility();

  (function() {
    const item = document.createElement('div');
    accordion.appendChild(item);
    item.classList.add('accordion-item');

    const div = document.createElement('div');
    item.appendChild(div);
    div.classList.add('form-check', 'form-switch');

    const input = document.createElement('input');
    div.appendChild(input);
    input.classList.add('form-check-input');
    input.type = 'checkbox';
    input.setAttribute('role', 'switch');
    input.id = 'layer' + layerId++;

    const label = document.createElement('label');
    div.appendChild(label);
    label.classList.add('form-check-label');
    label.setAttribute('for', input.id);
    label.innerHTML = 'Nedtonad bakgrund karta';

    input.checked = baseMapLayer === 'topowebb_nedtonad';
    input.onchange = function(event) {
      baseMapLayer = event.target.checked ? 'topowebb_nedtonad' : 'topowebb';
      baseMapSource.setUrl(`https://minkarta.lantmateriet.se/map/topowebbcache?LAYER=${encodeURIComponent(baseMapLayer)}`);

      const searchParams = new URLSearchParams(location.hash.substring(1));
      searchParams.set('basemap', baseMapLayer);
      location.hash = '#' + searchParams.toString();
    };
  })();
})();

/* legend panel */
(function() {
  const modal = document.getElementById('map-legend-panel');
  modal.classList.add('modal');
  modal.setAttribute('role', 'dialog');
  modal.setAttribute('aria-hidden', 'true');

  const content = document.createElement('div');
  modal.appendChild(content);
  content.classList.add('modal-content');

  const body = document.createElement('div');
  content.appendChild(body);
  body.classList.add('modal-body');
  body.innerHTML = 'legend TODO';
})();

/* popup and feature overlays */
(function() {
  const popupOverlay = new Overlay({
    stopEvent: true,
    element: popup,
  });
  map.addOverlay(popupOverlay);

  map.addLayer(new VectorLayer({
    source: featureOverlaySource,
    style: new Style({
      stroke: new Stroke({
        color: 'rgba(0, 255, 255, .8)',
        width: 3,
      }),
    }),
  }));

  const features = [];
  let popover, featureNum = 0;

  const header = document.createElement('div');
  header.classList.add('d-flex');

  const headerGrabbingArea = document.createElement('div');
  headerGrabbingArea.classList.add('flex-grow-1', 'grabbing-area', 'pe-2', 'me-2');
  header.appendChild(headerGrabbingArea);

  headerGrabbingArea.onmousedown = function(event) {
    if (event.button != 0) {
      return;
    }
    const popoverTip = Popover.getInstance(popup).tip;
    pageNode.classList.add('grabbing-area-grabbed');

    if (!popoverTip.classList.contains('popover-detached')) {
      /* detach popover tip */
      popoverTip.classList.add('popover-detached');
      const rect = popoverTip.getBoundingClientRect();
      const maxHeight = document.getElementById('map').getBoundingClientRect().height - 1 - rect.top -
        popoverTip.getElementsByClassName('popover-header')[0].getBoundingClientRect().height;

      const style = popoverTip.style;
      style.display = 'none'; /* avoid reflows between the following assignments */
      style.position = 'absolute';
      style.transform = '';
      style.inset = `${rect.top}px auto auto ${rect.left}px`;
      style.display = '';
    }

    let clientX = event.clientX, clientY = event.clientY;
    document.onmousemove = function(event) {
      const offsetX = clientX - event.clientX;
      const offsetY = clientY - event.clientY;
      clientX = event.clientX;
      clientY = event.clientY;
      popoverTip.style.top  = (popoverTip.offsetTop  - offsetY).toString() + 'px';
      popoverTip.style.left = (popoverTip.offsetLeft - offsetX).toString() + 'px';
    };

    document.onmouseup = function(event) {
      if (event.button != 0) {
        return;
      }
      pageNode.classList.remove('grabbing-area-grabbed');
      document.onmousemove = null;
      document.onmouseup = null;
    };
  };

  const pageNode = document.createElement('h6');
  headerGrabbingArea.appendChild(pageNode);

  const pageNum = document.createElement('span');
  const pageCount = document.createElement('span');
  pageNode.appendChild(document.createTextNode('Träff '));
  pageNode.appendChild(pageNum);
  pageNode.appendChild(document.createTextNode(' av '));
  pageNode.appendChild(pageCount);

  const onClickPageChange = function(event, offset) {
    const btn = event.target;
    if (btn.classList.contains('disabled') || popover === null || popover.tip === null) {
      return;
    }
    if (featureNum + offset < 0 || featureNum + offset > features.length - 1) {
      return;
    }

    featureNum += offset;
    if (featureNum < 1) {
      btnPrev.classList.add('disabled');
    } else {
      btnPrev.classList.remove('disabled');
    }
    if (featureNum < features.length - 1) {
      btnNext.classList.remove('disabled');
    } else {
      btnNext.classList.add('disabled');
    }

    const x = features[featureNum];
    featureOverlaySource.clear(true);
    featureOverlaySource.addFeature(x.feature);

    pageNum.innerHTML = (featureNum + 1).toString();
    popover.tip.getElementsByClassName('popover-body')[0].
      replaceChildren(x.formattedContent);
    setTimeout(function() { btn.blur() }, 100);
  };

  const btnPrev = document.createElement('button');
  btnPrev.classList.add('popover-button', 'popover-button-prev');
  btnPrev.setAttribute('type', 'button');
  btnPrev.title = 'Föregående träff';
  btnPrev.setAttribute('aria-label', btnPrev.title);
  btnPrev.onclick = function(event) {
    return onClickPageChange(event, -1);
  };

  const btnNext = document.createElement('button');
  btnNext.classList.add('popover-button', 'popover-button-next');
  btnNext.setAttribute('type', 'button');
  btnNext.title = 'Nästa träff';
  btnNext.setAttribute('aria-label', btnNext.title);
  btnNext.onclick = function(event) {
    return onClickPageChange(event, +1);
  };

  const btnClose = document.createElement('button');
  btnClose.classList.add('popover-button', 'popover-button-close');
  btnClose.setAttribute('type', 'button');
  btnClose.title = 'Stäng';
  btnClose.setAttribute('aria-label', btnClose.title);
  btnClose.onclick = function(event) {
    featureOverlaySource.clear(true);
    if (popover !== null) {
      popover.dispose();
    }
  };

  header.appendChild(btnPrev);
  header.appendChild(btnNext);
  header.appendChild(btnClose);

  const container0 = map.getViewport().getElementsByClassName('ol-overlaycontainer-stopevent')[0];
  map.on('singleclick', function(event) {
    /* clear the features list */
    featureOverlaySource.clear(true);
    features.length = 0;
    featureNum = 0;

    /* dispose any pre-existing popover */
    popover = Popover.getInstance(popup);
    if (popover !== null) {
      popover.dispose();
    }

    const size = map.getSize();
    if (size[0] < 576 || size[1] < 576) {
      return;
    }

    /* unclear how many feature we'll find, don't render prev/next buttons for now */
    pageNode.classList.add('d-none');
    btnPrev.classList.add('d-none', 'disabled');
    btnNext.classList.add('d-none', 'disabled');

    map.forEachFeatureAtPixel(event.pixel, function(feature, layer) {
      const properties = feature.getProperties();
      const def = layers[properties.layer];
      if (def === undefined || def.popover === undefined) {
        /* skip layers which didn't opt-in for popover */
        return;
      }

      /* turn the properties into a fine table */
      const table = document.createElement('table');
      table.classList.add('table', 'table-sm', 'table-borderless', 'table-hover');

      const tbody = document.createElement('tbody');
      table.appendChild(tbody);

      def.popover.forEach(function([desc, key, opts]) {
        let v = properties[key];
        if (opts === undefined) {
          opts = {};
        }
        if (opts.fn !== undefined) {
          v = opts.fn(v);
        }
        if (opts.unit !== undefined && v !== undefined && v !== '') {
          v += '\u202F' + opts.unit;
        }
        if (v === undefined) {
          v = document.createTextNode('');
        } else if (!(v instanceof HTMLElement)) {
          v = document.createTextNode(v);
        }

        const tr = document.createElement('tr');
        tbody.appendChild(tr);

        const td1 = document.createElement('td');
        tr.appendChild(td1);
        const textDesc = document.createTextNode(desc);
        td1.appendChild(textDesc);

        const td2 = document.createElement('td');
        tr.appendChild(td2);
        td2.appendChild(v);
        if (opts.classes !== undefined) {
          opts.classes.forEach((c) => td2.classList.add(c));
        }
      });

      const content = document.createElement('div');
      if (def.popoverTitle !== undefined) {
        const h = document.createElement('h6');
        content.appendChild(h);
        const textNode = document.createTextNode(def.popoverTitle);
        h.appendChild(textNode);
      }

      // console.log(properties);
      content.appendChild(table);
      features.push({feature: feature, formattedContent: content});

      pageCount.innerHTML = features.length.toString();
      if (features.length == 2) {
        /* there are ≥2 features, render prev/pre buttons */
        btnNext.classList.remove('d-none', 'disabled');
        btnPrev.classList.remove('d-none');
        pageNode.classList.remove('d-none');
      }

      if (popover === null || popover.tip === null) {
        /* create a new popover if we're not already showing one */
        pageNum.innerHTML = (featureNum + 1).toString();
        popupOverlay.setPosition(event.coordinate);

        popover = new Popover(popup, {
          template: '<div class="popover" role="tooltip"><div class="popover-arrow"></div>' +
                    '<div class="popover-header"></div><div class="popover-body"></div></div>',
          title: header,
          content: content,
          html: true,
          placement: 'right',
          fallbackPlacements: ['right', 'left', 'bottom', 'top'],
          container: container0,
        });
        popover.show();
        featureOverlaySource.addFeature(feature);
      }
    }, {
      hitTolerance: 5,
      checkWrapped: false,
      layerFilter: (l) => l === vectorLayer || l === vectorLayer2,
    });
  });
}());