Mark unsupported platforms

Author: dima-dencep

build.gradle

@@ -5,7 +5,7 @@ plugins {
 }
 
 base.archivesName = "PlatformTools"
-version = "1.0.2"
+version = "1.0.3"
 group = "org.redlance"
 
 repositories {

src/main/java/org/redlance/platformtools/impl/PlatformFileRefererImpl.java

@@ -4,6 +4,7 @@
 import org.jetbrains.annotations.Nullable;
 import org.redlance.platformtools.PlatformFileReferer;
 import org.redlance.platformtools.impl.macos.MacFileReferer;
+import org.redlance.platformtools.impl.unsupported.UnsupportedPlatform;
 import org.redlance.platformtools.impl.windows.WindowsFileReferer;
 
 import java.io.IOException;
@@ -12,7 +13,7 @@ public class PlatformFileRefererImpl implements PlatformFileReferer {
     private final PlatformFileReferer nativePlatformReferer = switch (Platform.getOSType()) {
         case Platform.WINDOWS -> new WindowsFileReferer();
         case Platform.MAC -> new MacFileReferer();
-        default -> null;
+        default -> UnsupportedPlatform.INSTANCE;
     };
 
     @Override

src/main/java/org/redlance/platformtools/impl/TestingApp.java

@@ -53,6 +53,7 @@ private void onChooseFile(ActionEvent e) {
             try {
                 String referrer = PlatformFileReferer.INSTANCE.getFileReferer(fileChooser.getSelectedFile());
                 this.referrerLabel.setText("Referrer: " + referrer);
+                System.out.println(referrer);
             } catch (IOException ex) {
                 throw new RuntimeException(ex);
             }

src/main/java/org/redlance/platformtools/impl/unsupported/UnsupportedPlatform.java

@@ -0,0 +1,16 @@
+package org.redlance.platformtools.impl.unsupported;
+
+import com.sun.jna.Platform;
+import org.redlance.platformtools.PlatformFileReferer;
+
+public final class UnsupportedPlatform implements PlatformFileReferer {
+    private static final String UNSUPPORTED_STRING = String.format("Unsupported platform: %s", Platform.getOSType());
+    public static final UnsupportedPlatform INSTANCE = new UnsupportedPlatform();
+
+    private UnsupportedPlatform() {}
+
+    @Override
+    public String getFileReferer(String path) {
+        return UNSUPPORTED_STRING;
+    }
+}