Use generic GraphHopper engine

app/assets/javascripts/routing_engines/graphhopper.js

@@ -0,0 +1,63 @@
+GraphHopperEngine = function(vehicleName, vehicleParam, locale) {
+    this.vehicleName = vehicleName;
+    this.vehicleParam = vehicleParam;
+    this.locale = locale;
+    if (!locale)
+        this.locale = "en";
+};
+
+GraphHopperEngine.prototype.createConfig = function() {
+    var that = this;
+    return {
+        name: "javascripts.directions.engines.graphhopper_"+this.vehicleName.toLowerCase(),
+        draggable: false,
+        _hints: {},
+        getRoute: function(isFinal, points) {
+            var url = "http://graphhopper.com/routing/api/route?" 
+                    + that.vehicleParam 
+                    + "&locale=" + that.locale;
+            for (var i = 0; i < points.length; i++) {
+                var pair = points[i].join(',');
+                url += "&point=" + pair;
+            }            
+            if (isFinal)
+                url += "&instructions=true";
+            // GraphHopper supports json too
+            this.requestJSONP(url + "&type=jsonp&callback=");
+        },
+        gotRoute: function(router, data) {
+            if (!data.info.routeFound) {
+                return false;
+            }
+            // Draw polyline
+            var line = L.PolylineUtil.decode(data.route.coordinates);
+            router.setPolyline(line);
+            // Assemble instructions
+            var steps = [];
+            var instr = data.route.instructions;
+            for (i = 0; i < instr.descriptions.length; i++) {
+                var indi = instr.indications[i];
+                var instrCode = (i == instr.descriptions.length - 1) ? 15 : this.GH_INSTR_MAP[indi];
+                var instrText = "<b>" + (i + 1) + ".</b> ";
+                instrText += instr.descriptions[i];
+                var latlng = instr.latLngs[i];
+                var distInMeter = instr.distances[i];
+                steps.push([{lat: latlng[0], lng: latlng[1]}, instrCode, instrText, distInMeter]);
+            }
+            router.setItinerary({steps: steps});
+            return true;
+        },
+        GH_INSTR_MAP: {
+            "-3": 6, // sharp left
+            "-2": 7, // left	
+            "-1": 8, // slight left                
+            0: 0, // straight
+            1: 1, // slight right
+            2: 2, // right
+            3: 3 // sharp right		
+        }
+    };
+};
+
+OSM.RoutingEngines.list.push(new GraphHopperEngine("Bicycle", "vehicle=bike").createConfig());
+OSM.RoutingEngines.list.push(new GraphHopperEngine("Foot", "vehicle=foot").createConfig());