import Map from '../src/ol/Map.js';
import View from '../src/ol/View.js';
import GeoJSON from '../src/ol/format/GeoJSON.js';
import {Tile as TileLayer, Vector as VectorLayer} from '../src/ol/layer.js';
import {OSM, Vector as VectorSource} from '../src/ol/source.js';

const map = new Map({
  layers: [
    new TileLayer({
      source: new OSM()
    }),
    new VectorLayer({
      source: new VectorSource({
        url: 'data/geojson/countries.geojson',
        format: new GeoJSON()
      }),
      opacity: 0.5
    })
  ],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2
  })
});

document.getElementById('export-png').addEventListener('click', function() {
  map.once('rendercomplete', function() {
    const mapCanvas = document.createElement('canvas');
    const size = map.getSize();
    mapCanvas.width = size[0];
    mapCanvas.height = size[1];
    const mapContext = mapCanvas.getContext('2d');
    Array.prototype.forEach.call(document.querySelectorAll('.ol-layer canvas'), function(canvas) {
      if (canvas.width > 0) {
        const opacity = canvas.parentNode.style.opacity;
        mapContext.globalAlpha = opacity === '' ? 1 : Number(opacity);
        const transform = canvas.style.transform;
        // Get the transform parameters from the style's transform matrix
        const matrix = transform.match(/^matrix\(([^\(]*)\)$/)[1].split(',').map(Number);
        // Apply the transform to the export map context
        CanvasRenderingContext2D.prototype.setTransform.apply(mapContext, matrix);
        mapContext.drawImage(canvas, 0, 0);
      }
    });
    if (navigator.msSaveBlob) {
      // link download attribuute does not work on MS browsers
      navigator.msSaveBlob(mapCanvas.msToBlob(), 'map.png');
    } else {
      const link = document.getElementById('image-download');
      link.href = mapCanvas.toDataURL();
      link.click();
    }
  });
  map.renderSync();
});