Fixes waypoint index

Fix mapbox#184

src/directions.js

@@ -98,7 +98,9 @@ export default class MapboxDirections {
    * @returns {Control} `this`
    */
   onRemove(map) {
-    this.container.parentNode.removeChild(this.container);
+    if (this.container.parentNode !== null) {
+      this.container.parentNode.removeChild(this.container);
+    }
     this.removeRoutes();
     map.off('mousedown', this.onDragDown);
     map.off('mousemove', this.move);
@@ -363,7 +365,7 @@ export default class MapboxDirections {
   _onDragUp() {
     if (!this.isDragging) return;
 
-    const { hoverMarker, origin, destination } = store.getState();
+    const { hoverMarker, origin, destination, waypoints } = store.getState();
 
     switch (this.isDragging.layer.id) {
       case 'directions-origin-point':
@@ -375,7 +377,9 @@ export default class MapboxDirections {
       case 'directions-hover-point':
         // Add waypoint if a sufficent amount of dragging has occurred.
         if (hoverMarker.geometry && !utils.coordinateMatch(this.isDragging, hoverMarker)) {
-          this.actions.addWaypoint(0, hoverMarker);
+          const click = this.isDragging.geometry.coordinates;
+          const index = utils.getNextWaypoint(this.getRoute.bind(this), waypoints, click);
+          this.actions.addWaypoint(index, hoverMarker);
         }
       break;
     }
@@ -520,7 +524,22 @@ export default class MapboxDirections {
   getWaypoints() {
     return store.getState().waypoints;
   }
-
+
+  /**
+   * Fetch all current points in a route.
+   * @returns {Array} route points
+   */
+  getRoute() {
+    return this
+      ._map
+      .getSource('directions')
+      ._data
+      .features
+      .find(({geometry}) => geometry.type === 'LineString')
+      .geometry
+      .coordinates;
+  }
+
   /**
    * Removes all routes and waypoints from the map.
    *

src/utils.js

@@ -62,4 +62,43 @@ const format = {
   }
 };
 
-export default { format, coordinateMatch, createPoint, validCoords, wrap, roundWithOriginalPrecision };
+const distance = ([x1, y1], [x2, y2]) =>
+  Math.hypot((x1 - x2), (y1 - y2));
+
+const nearest = origin =>
+  (p1, p2, index) =>
+    (distance(origin, p1) < distance(origin, p2))
+      ? p1
+      : p2.concat(index);
+
+
+const find = (route, origin) => route
+  .reduce(nearest(origin), [Infinity, Infinity, -1])[2];
+
+const compare = point =>
+  waypoint =>
+    coordinateMatch(point, waypoint);
+
+const getNextWaypoint = (getRoute, waypoints, origin) => {
+  if (waypoints.length === 0) return 0;
+
+  const route = getRoute();
+
+  for(let i = find(route, origin); i < route.length; i++) {
+    const index = waypoints.findIndex(compare({ geometry: { coordinates: route[i] } }));
+    if (index !== -1) {
+      return index;  
+    }
+  }
+  return waypoints.length;
+};
+
+export default { 
+  format, 
+  coordinateMatch, 
+  createPoint, 
+  validCoords, 
+  wrap, 
+  roundWithOriginalPrecision, 
+  getNextWaypoint 
+};