Finish the nearest plugin

include/engine/api/nearest_api.hpp

@@ -0,0 +1,55 @@
+#ifndef ENGINE_API_NEAREST_API_HPP
+#define ENGINE_API_NEAREST_API_HPP
+
+#include "engine/api/base_api.hpp"
+#include "engine/api/nearest_parameters.hpp"
+
+#include "engine/api/json_factory.hpp"
+#include "engine/phantom_node.hpp"
+
+#include <boost/assert.hpp>
+
+#include <vector>
+
+namespace osrm
+{
+namespace engine
+{
+namespace api
+{
+
+class NearestAPI final : public BaseAPI
+{
+  public:
+    NearestAPI(const datafacade::BaseDataFacade &facade_, const NearestParameters &parameters_)
+        : BaseAPI(facade_, parameters_), parameters(parameters_)
+    {
+    }
+
+    void MakeResponse(const std::vector<std::vector<PhantomNodeWithDistance>> &phantom_nodes, util::json::Object& response) const
+    {
+        BOOST_ASSERT(phantom_nodes.size() == 1);
+        BOOST_ASSERT(parameters.coordinates.size() == 1);
+
+        util::json::Array waypoints;
+        waypoints.values.resize(phantom_nodes.front().size());
+        std::transform(phantom_nodes.front().begin(),
+            phantom_nodes.front().end(), waypoints.values.begin(), [this](const PhantomNodeWithDistance& phantom_with_distance)
+            {
+                auto waypoint = MakeWaypoint(parameters.coordinates.front(), phantom_with_distance.phantom_node);
+                waypoint.values["distance"] = phantom_with_distance.distance;
+                return waypoint;
+            });
+
+        response.values["code"] = "ok";
+        response.values["waypoints"] = std::move(waypoints);
+    }
+
+    const NearestParameters &parameters;
+};
+
+} // ns api
+} // ns engine
+} // ns osrm
+
+#endif