Final part of check update feature: backend part

Author: introfog

src/main/java/com/github/introfog/gitwave/model/AppConstants.java

@@ -21,6 +21,8 @@ public final class AppConstants {
     public static final String LINK_TO_GIT_CONTRIBUTING_FILE = "https://github.com/introfog/GitWave/blob/master/CONTRIBUTING.md";
     public static final String LINK_TO_GIT_REPO = "https://github.com/introfog/GitWave";
     public static final String LINK_TO_GIT_RELEASES = "https://github.com/introfog/GitWave/releases";
+    public static final String GIT_HUB_REPO_OWNER = "introfog";
+    public static final String APP_NAME = "GitWave";
     public static final String PATH_TO_LOGO = "/logo.png";
     // TODO make pretty logo
 

src/main/java/com/github/introfog/gitwave/model/UpdateChecker.java

@@ -16,12 +16,74 @@
 
 package com.github.introfog.gitwave.model;
 
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 public final class UpdateChecker {
+    private static final Pattern TAG_NAME_PATTERN = Pattern.compile("\"name\":\\s?\"([^\"]+)\"");
+    private static final Logger LOGGER = LoggerFactory.getLogger(UpdateChecker.class);
+
     private UpdateChecker() {
         // Do nothing
     }
 
     public static boolean isNewReleaseAvailable() {
-        return true;
+        // TODO MINOR fetch and check update in the separate thread, to quicker open app.
+        final String latestTag = fetchLatestTag(AppConstants.GIT_HUB_REPO_OWNER, AppConstants.APP_NAME);
+        LOGGER.info("Fetch '{}' tag from GitHub repo.", latestTag);
+        return latestTag != null && !AppConstants.VERSION.equals(latestTag);
+    }
+
+    public static String fetchLatestTag(String owner, String repo) {
+        final String apiUrl = "https://api.github.com/repos/" + owner + "/" + repo + "/tags";
+
+        try {
+            HttpURLConnection connection = (HttpURLConnection) new URL(apiUrl).openConnection();
+            connection.setConnectTimeout(5000);
+            connection.setReadTimeout(5000);
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Accept", "application/vnd.github.v3+json");
+            connection.setRequestProperty("User-Agent", "GitWave/" + AppConstants.VERSION + " (Java; en-US)");
+            connection.connect();
+
+            if (connection.getResponseCode() != 200) {
+                LOGGER.warn("Failed to fetch tags from GitHub API: code='{}', body='{}'",
+                        connection.getResponseCode(), connection.getResponseMessage());
+                return null;
+            }
+
+            String responseStr = inputStreamToString(connection.getInputStream());
+            connection.disconnect();
+            // Use here regex on purpose, to not increase size of the app by adding huge library for one request.
+            Matcher matcher = TAG_NAME_PATTERN.matcher(responseStr);
+
+            if (matcher.find()) {
+                return matcher.group(1);
+            }
+            return null;
+
+        } catch (Exception e) {
+            LOGGER.warn("Error fetching latest version from GitHub", e);
+            return null;
+        }
+    }
+
+    private static String inputStreamToString(InputStream inputStream) throws IOException {
+        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
+        StringBuilder result = new StringBuilder();
+        String line;
+        while ((line = reader.readLine()) != null) {
+            result.append(line);
+        }
+        reader.close();
+        return result.toString();
     }
 }