refactor: first attempt at dependency injection

also some more renaming and improving date-picker dialog

src/main/java/ch/zhaw/gartenverwaltung/PlantsController.java

@@ -10,11 +10,7 @@ import javafx.beans.property.SimpleListProperty;
 import javafx.collections.FXCollections;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
-import javafx.fxml.FXMLLoader;
-import javafx.fxml.Initializable;
 import javafx.geometry.Insets;
-import javafx.scene.Parent;
-import javafx.scene.Scene;
 import javafx.scene.control.*;
 import javafx.scene.image.Image;
 import javafx.scene.image.ImageView;
@@ -23,22 +19,27 @@ import javafx.stage.Modality;
 import javafx.stage.Stage;
 
 import java.io.IOException;
-import java.net.URL;
 import java.util.List;
-import java.util.Objects;
-import java.util.ResourceBundle;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-public class PlantsController implements Initializable {
+public class PlantsController {
     private static final Logger LOG = Logger.getLogger(PlantsController.class.getName());
-    private final PlantListModel plantListModel = new PlantListModel();
+    private PlantListModel plantListModel;
+    private MainFXMLController mainController;
     private Plant selectedPlant = null;
     private final HardinessZone DEFAULT_HARDINESS_ZONE = HardinessZone.ZONE_8A;
 
     // TODO: move to model
     private final ListProperty<Plant> plantListProperty = new SimpleListProperty<>(FXCollections.observableArrayList());
 
+    @SuppressWarnings("unused")
+    public void injectDependencies(PlantListModel plantListModel, MainFXMLController mainController) {
+        this.plantListModel =  plantListModel;
+        this.mainController = mainController;
+        init();
+    }
+
     @FXML
     private VBox seasons;
 
@@ -66,13 +67,11 @@ public class PlantsController implements Initializable {
      */
     @FXML
     void selectSowDate(ActionEvent event) throws IOException {
-        Parent root;
-        FXMLLoader fxmlLoader = new FXMLLoader(Objects.requireNonNull(getClass().getResource("SelectSowDay.fxml")));
-        root = fxmlLoader.load();
-        SelectSowDayController controller = fxmlLoader.getController();
-        controller.getSelectedPlant(selectedPlant);
         Stage stage = new Stage();
-        stage.setScene(new Scene(root));
+        if (mainController.loadSceneToStage("SelectSowDay.fxml", stage) instanceof SelectSowDayController controller) {
+            controller.setSelectedPlant(selectedPlant);
+        }
+
         stage.initModality(Modality.APPLICATION_MODAL);
         stage.setResizable(false);
         stage.showAndWait();
@@ -85,8 +84,7 @@ public class PlantsController implements Initializable {
      * create event listener for selected list entry and search by query
      * {@inheritDoc}
      */
-    @Override
-    public void initialize(URL url, ResourceBundle resourceBundle) {
+    public void init() {
         setListCellFactory();
         fillPlantListWithHardinessZone();
         list_plants.itemsProperty().bind(plantListProperty);