Include update checker

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>xyz.jpenilla</groupId>
     <artifactId>DynamicShop-Graph</artifactId>
-    <version>0.2.2-SNAPSHOT.{BUILD_NUMBER}</version>
+    <version>0.2.2</version>
     <packaging>jar</packaging>
 
     <name>DynamicShop Graph</name>

src/main/java/xyz/jpenilla/dsgraph/DSGraph.java

@@ -43,6 +43,11 @@ public void onEnable() {
         Metrics metrics = new Metrics(this, pluginId);
         metrics.addCustomChart(new Metrics.SimplePie("amount_of_items_tracked", () -> String.valueOf(cfg.getFiles().size())));
 
+        new UpdateChecker(this, 80638).getVersion(version -> {
+            if (!this.getDescription().getVersion().equalsIgnoreCase(version)) {
+                getLogger().info("There is an update available for DynamicShop-Graph (" + version + ") at https://www.spigotmc.org/resources/dynamicshop-graph.80638/");
+            }
+        });
     }
 
     @Override

src/main/java/xyz/jpenilla/dsgraph/UpdateChecker.java

@@ -0,0 +1,33 @@
+package xyz.jpenilla.dsgraph;
+
+import org.bukkit.Bukkit;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.util.Consumer;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.Scanner;
+
+public class UpdateChecker {
+
+    private final Plugin plugin;
+    private final int resourceId;
+
+    public UpdateChecker(Plugin plugin, int resourceId) {
+        this.plugin = plugin;
+        this.resourceId = resourceId;
+    }
+
+    public void getVersion(final Consumer<String> consumer) {
+        Bukkit.getScheduler().runTaskAsynchronously(this.plugin, () -> {
+            try (InputStream inputStream = new URL("https://api.spigotmc.org/legacy/update.php?resource=" + this.resourceId).openStream(); Scanner scanner = new Scanner(inputStream)) {
+                if (scanner.hasNext()) {
+                    consumer.accept(scanner.next());
+                }
+            } catch (IOException exception) {
+                this.plugin.getLogger().info("Cannot look for updates: " + exception.getMessage());
+            }
+        });
+    }
+}

src/main/resources/index.html

@@ -71,7 +71,7 @@
                 <ul>
                     <li><a class="grey-text text-lighten-3" href="https://github.com/jmanpenilla/DynamicShop-Graph">GitHub</a>
                     </li>
-                    <li><a class="grey-text text-lighten-3" href="#!">Spigot</a></li>
+                    <li><a class="grey-text text-lighten-3" href="https://www.spigotmc.org/resources/dynamicshop-graph.80638/">Spigot</a></li>
                 </ul>
             </div>
         </div>