Implement Set as next message button

src/main/java/name/nathanmcrae/numbersstation/MainController.java

@@ -116,6 +116,29 @@ public class MainController implements Initializable {
         }
     }
 
+    @FXML
+    private void handleSetAsNextMessageButtonPress() {
+        Path stationDirPath = selectedStation.stationPath();
+
+        try {
+            if (!Files.exists(stationDirPath)) {
+                Files.createDirectories(stationDirPath);
+            }
+
+            Path nextMessagePath = stationDirPath.resolve("next-message.txt");
+
+            Files.write(nextMessagePath, messageTextArea.getText().getBytes());
+        } catch (IOException e) {
+            String message = "Failed to write next message to " + stationDirPath.toString();
+            logger.log(Level.SEVERE, message, e);
+            Alert alert = new Alert(Alert.AlertType.ERROR);
+            alert.setTitle("Exception");
+            alert.setHeaderText(null);
+            alert.setContentText(message);
+            alert.showAndWait();
+        }
+    }
+
     @Override
     public void initialize(URL location, ResourceBundle resources) {
         stationNameField.textProperty().bindBidirectional(selectedStationName);

src/main/java/name/nathanmcrae/numbersstation/MainView.fxml

@@ -86,7 +86,7 @@
       </TextArea>
       <FlowPane alignment="CENTER_RIGHT" prefHeight="34.0" prefWidth="620.0" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0">
          <children>
-            <Button mnemonicParsing="false" text="Set as next message" />
+            <Button mnemonicParsing="false" onMousePressed="#handleSetAsNextMessageButtonPress" text="Set as next message" />
          </children>
       </FlowPane>
    </children>

src/main/java/name/nathanmcrae/numbersstation/StationSettings.java

@@ -1,5 +1,8 @@
 package name.nathanmcrae.numbersstation;
 
+import java.io.UnsupportedEncodingException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.time.LocalDate;
 import java.time.LocalTime;
 import java.util.ArrayList;
@@ -40,6 +43,25 @@ public class StationSettings {
         name = newName;
     }
 
+    public Path stationPath() {
+        String configHome = System.getenv("XDG_CONFIG_HOME");
+        Path directoryPath;
+
+        if (configHome != null && !configHome.isEmpty() && Paths.get(configHome).isAbsolute()) {
+            directoryPath = Paths.get(configHome, "numbers-station");
+        } else {
+            String userHome = System.getProperty("user.home");
+            directoryPath = Paths.get(userHome, ".config", "numbers-station");
+        }
+
+        String stationDirName = null;
+        try {
+            stationDirName = java.net.URLEncoder.encode(name, "UTF-8");
+        } catch(UnsupportedEncodingException e) {} // We know UTF-8 is supported
+
+        return directoryPath.resolve(stationDirName);
+    }
+
     public String getAddress() {
         return address;
     }