show badge for missing license key in window title

main/commons/src/main/java/org/cryptomator/common/LicenseChecker.java

@@ -19,7 +19,7 @@ import java.security.spec.X509EncodedKeySpec;
 import java.util.Optional;
 
 @Singleton
-public class LicenseChecker {
+class LicenseChecker {
 
 	private final JWTVerifier verifier;
 

main/commons/src/main/java/org/cryptomator/common/LicenseHolder.java

@@ -0,0 +1,79 @@
+package org.cryptomator.common;
+
+import com.auth0.jwt.interfaces.DecodedJWT;
+import javafx.beans.binding.Bindings;
+import javafx.beans.binding.BooleanBinding;
+import javafx.beans.binding.StringBinding;
+import javafx.beans.property.ObjectProperty;
+import javafx.beans.property.SimpleObjectProperty;
+import org.cryptomator.common.settings.Settings;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+import java.util.Optional;
+
+@Singleton
+public class LicenseHolder {
+
+	private final Settings settings;
+	private final LicenseChecker licenseChecker;
+	private final ObjectProperty<DecodedJWT> validJwtClaims;
+	private final StringBinding licenseSubject;
+	private final BooleanBinding validLicenseProperty;
+
+	@Inject
+	public LicenseHolder(LicenseChecker licenseChecker, Settings settings) {
+		this.settings = settings;
+		this.licenseChecker = licenseChecker;
+		this.validJwtClaims = new SimpleObjectProperty<>();
+		this.licenseSubject = Bindings.createStringBinding(this::getLicenseSubject, validJwtClaims);
+		this.validLicenseProperty = validJwtClaims.isNotNull();
+
+		Optional<DecodedJWT> claims = licenseChecker.check(settings.licenseKey().get());
+		validJwtClaims.set(claims.orElse(null));
+	}
+
+	public boolean validateAndStoreLicense(String licenseKey) {
+		Optional<DecodedJWT> claims = licenseChecker.check(licenseKey);
+		validJwtClaims.set(claims.orElse(null));
+		if (claims.isPresent()) {
+			settings.licenseKey().set(licenseKey);
+			return true;
+		} else {
+			return false;
+		}
+	}
+
+	/* Observable Properties */
+
+	public Optional<String> getLicenseKey() {
+		DecodedJWT claims = validJwtClaims.get();
+		if (claims != null) {
+			return Optional.of(claims.getToken());
+		} else {
+			return Optional.empty();
+		}
+	}
+
+	public StringBinding licenseSubjectProperty() {
+		return licenseSubject;
+	}
+
+	public String getLicenseSubject() {
+		DecodedJWT claims = validJwtClaims.get();
+		if (claims != null) {
+			return claims.getSubject();
+		} else {
+			return null;
+		}
+	}
+
+	public BooleanBinding validLicenseProperty() {
+		return validLicenseProperty;
+	}
+
+	public boolean isValidLicense() {
+		return validLicenseProperty.get();
+	}
+
+}