Merge pull request #42 from SAKPaaS/feature/#32_resultlist_begrenzen

Feature/#32 resultlist begrenzen

src/main/java/de/sakpaas/backend/model/Location.java

@@ -42,6 +42,4 @@ public class Location {
 
     @Column(name = "COUNTRY")
     private String country;
-
-
 }

src/main/java/de/sakpaas/backend/service/LocationService.java

@@ -1,13 +1,13 @@
 package de.sakpaas.backend.service;
 
 import de.sakpaas.backend.model.Location;
-import javassist.NotFoundException;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
-import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 @Service
 public class LocationService {
@@ -24,8 +24,23 @@ public Optional<Location> getById(long id) {
         return locationRepository.findById(id);
     }
 
+    public static double distanceInKm(double lat1, double lon1, double lat2, double lon2) {
+        //https://www.daniel-braun.com/technik/distanz-zwischen-zwei-gps-koordinaten-in-java-berchenen/
+        int radius = 6371;
+        double lat = Math.toRadians(lat2 - lat1);
+        double lon = Math.toRadians(lon2 - lon1);
+        double a = Math.sin(lat / 2) * Math.sin(lat / 2) + Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) * Math.sin(lon / 2) * Math.sin(lon / 2);
+        double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+        double d = radius * c;
+        return Math.abs(d);
+    }
+
     public List<Location> findByCoordinates(Double lat, Double lon) {
-        return locationRepository.findByLatitudeBetweenAndLongitudeBetween(lat - 0.1, lat + 0.1, lon - 0.1, lon + 0.1);
+        List<Location> list = locationRepository.findByLatitudeBetweenAndLongitudeBetween(lat - 0.1, lat + 0.1, lon - 0.1, lon + 0.1);
+        return list.stream()
+                .sorted(Comparator.comparingDouble(l -> distanceInKm(l.getLatitude(), l.getLongitude(), lat, lon)))
+                .limit(100)
+                .collect(Collectors.toList());
     }
 
     public Location save(Location location) {