Auto-update from Gitlab's latest tag

src/main/java/es/kauron/jstudy/controller/Controller.java

@@ -24,16 +24,25 @@ import javafx.scene.layout.BorderPane;
 import javafx.stage.FileChooser;
 import javafx.stage.Window;
 import javafx.stage.WindowEvent;
+import org.json.JSONArray;
+import org.json.JSONObject;
 
 import java.awt.*;
-import java.io.File;
-import java.io.IOException;
+import java.io.*;
+import java.net.HttpURLConnection;
 import java.net.URI;
 import java.net.URL;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
 import java.util.List;
 import java.util.*;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 public class Controller implements Initializable {
+    private static final String PROJECT_URL = "https://gitlab.com/kauron/jstudy";
+
     @FXML
     private TabPane tabPane;
 
@@ -45,6 +54,7 @@ public class Controller implements Initializable {
 
     private final BooleanProperty tabIsTable = new SimpleBooleanProperty(false);
     private final Map<Tab, TableController> tabMap = new HashMap<>();
+    private String updateURL, updateFileName;
 
     @Override
     public void initialize(URL url, ResourceBundle resourceBundle) {
@@ -65,6 +75,75 @@ public class Controller implements Initializable {
                 }
             })
         );
+        new Thread(this::checkUpdate).start();
+    }
+
+    private void checkUpdate() {
+        // Check new version via gitlab's REST API
+        String newVersion;
+        File jarFile;
+        BufferedReader br;
+        try {
+            URL apiUrl = new URL("https://gitlab.com/api/v4/projects/9264549/releases");
+            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Accept", "application/json");
+            if (connection.getResponseCode() != 200) {
+                System.err.println("Error connecting to Gitlab API");
+            }
+            br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+        } catch (IOException e) {
+            return;
+        }
+        String output = br.lines().collect(Collectors.joining());
+        JSONArray tags = new JSONArray(output);
+        JSONObject latest = tags.getJSONObject(0);
+        newVersion = latest.getString("tag_name").substring(1);
+        if (!isNewVersion(AppPrefs.getVersion(), newVersion))
+            return;
+        String desc = latest.getString("description");
+        Matcher matcher = Pattern.compile("\\[(.*\\.jar)]" +
+                "\\((/uploads/.*/.*\\.jar)\\)").matcher(desc);
+        if (!matcher.find())
+            return;
+        updateURL = matcher.group(2);
+        updateFileName = matcher.group(1);
+        // Ask user whether to update or not.
+        Platform.runLater(this::onUpdate);
+    }
+
+    private void onUpdate() {
+        Optional<ButtonType> res = new Alert(Alert.AlertType.INFORMATION,
+                "There is an update ready. Would you like to download it and open it?",
+                ButtonType.YES, ButtonType.NO).showAndWait();
+        if (!res.isPresent() || !res.get().equals(ButtonType.YES))
+            return;
+        try (InputStream inputStream = new URL(PROJECT_URL + updateURL).openStream();
+             ReadableByteChannel readableByteChannel = Channels.newChannel(inputStream);
+             FileOutputStream fileOutputStream = new FileOutputStream(updateFileName)) {
+            fileOutputStream.getChannel().transferFrom(readableByteChannel, 0, Long.MAX_VALUE);
+        } catch (IOException e) {
+            return;
+        }
+        // Launch new version
+        try {
+            new ProcessBuilder("java", "-jar", updateFileName).start();
+        } catch (IOException e) {
+            return;
+        }
+        onQuit(null);
+    }
+
+    private boolean isNewVersion(String version, String newVersion) {
+        String[] o = version.split("\\.");
+        String[] n = newVersion.split("\\.");
+        for (int i = 0; i < o.length; i++) {
+            int a = Integer.parseInt(n[i]);
+            int b = Integer.parseInt(o[i]);
+            if (a != b)
+                return a > b;
+        }
+        return false;
     }
 
     @FXML
@@ -248,7 +327,7 @@ public class Controller implements Initializable {
     protected void onAboutAction(ActionEvent event) {
         if (Desktop.isDesktopSupported()) {
             try {
-                Desktop.getDesktop().browse(URI.create("https://gitlab.com/kauron/jstudy"));
+                Desktop.getDesktop().browse(URI.create(PROJECT_URL));
             } catch (Exception e) {
                 e.printStackTrace();
             }

src/main/java/es/kauron/jstudy/model/AppPrefs.java

@@ -4,6 +4,7 @@ import es.kauron.jstudy.Main;
 import javafx.beans.property.SimpleBooleanProperty;
 
 import java.io.File;
+import java.util.Scanner;
 import java.util.prefs.BackingStoreException;
 import java.util.prefs.Preferences;
 
@@ -33,6 +34,12 @@ public class AppPrefs {
         flushPrefs();
     }
 
+    public static String getVersion() {
+        String v = new Scanner(AppPrefs.class.getResourceAsStream("/version.txt")).nextLine();
+        assert v.matches("\\d\\.\\d\\.\\d");
+        return v;
+    }
+
     public static class BooleanPref extends SimpleBooleanProperty {
         private final String name;
 

src/main/main.iml

@@ -9,5 +9,6 @@
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="library" name="Maven: com.jfoenix:jfoenix:8.0.9" level="project" />
+    <orderEntry type="library" name="Maven: org.json:json:20190722" level="project" />
   </component>
 </module>

src/main/resources-filtered/version.txt

@@ -0,0 +1 @@
+${version}