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

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];

const map = new Map({
  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, 4, 2, 1, .5],
    constrainResolution: false,
  }),
  layers: [
    new TileLayer({
      /* 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/
       */
      source: new WMTS({
        url: 'https://minkarta.lantmateriet.se/map/topowebbcache',
        version: '1.0.0',
        layer: 'topowebb',
        style: 'default',
        matrixSet: '3006',
        format: 'image/png',
        tileGrid: new WMTSTileGrid({
          extent: extent,
          // https://www.lantmateriet.se/globalassets/geodata/geodatatjanster/tb_twk_visning_cache_v1.1.0.pdf
          tileSize: 256,
          origin: [-1200000, 8500000],
          resolutions: [4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1, .5],
          matrixIds: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13],
        }),
        projection: projection,
        wrapX: false,
        crossOrigin: 'anonymous',
        attributions: '&copy; <a href="https://lantmateriet.se" target="_blank">Lantmäteriet</a>',
      }),
    }),
  ],
  target: document.getElementById('map'),
});