/**
 * Based on https://github.com/mikhailshilkov/leaflet-corridor
 */

const leaflet = require('leaflet');

/**
 * Polyline whose weight is based on a fixed number of meters of thickness
 * rather than a static number of pixels.
 */
const Corridor = leaflet.Polyline.extend({
    initialize(latlngs, options)
    {
        leaflet.Polyline.prototype.initialize.call(this, latlngs, options);

        this.corridor = options.corridor;
    },

    onAdd(map)
    {
        leaflet.Polyline.prototype.onAdd.call(this, map);
        map.on('zoomend', () => this._updateWeight(map));
        this._updateWeight(map);
    },

    onRemove(map)
    {
        map.off('zoomend', () => this._updateWeight(map));
        leaflet.Polyline.prototype.onRemove.call(this, map);
    },

    /**
     * Update the actual line weight to span the requested number of meters
     * based on the current meter density.
     */
    _updateWeight(map)
    {
        this.setStyle({
            weight: this.corridor / this._getMetersPerPixel(map)
        });
    },

    /**
     * Calculate how many meters are in a pixel at the current zoom level
     * around the current center point.
     *
     * @param map Map to take the zoom level from.
     * @return Number of meters per pixel.
     */
    _getMetersPerPixel(map)
    {
        const centerLatLng = map.getCenter();
        const centerPixels = map.latLngToContainerPoint(centerLatLng);

        // Place two points left and right of the center
        const point1 = leaflet.point(centerPixels.x + 5, centerPixels.y);
        const point2 = leaflet.point(centerPixels.x - 5, centerPixels.y);

        // Convert back to latitude and longitude then compute distance
        const point1LatLng = map.containerPointToLatLng(point1);
        const point2LatLng = map.containerPointToLatLng(point2);

        console.log(point1LatLng.distanceTo(point2LatLng) / 10, 'mètres par pixel');
        return point1LatLng.distanceTo(point2LatLng) / 10;
    },
});

module.exports = (latlngs, options) => new Corridor(
    latlngs,
    options || { corridor: 100 }
);