added update notification

src/main/java/net/thenextlvl/gopaint/GoPaintPlugin.java

@@ -24,6 +24,7 @@
 import net.thenextlvl.gopaint.listener.ConnectListener;
 import net.thenextlvl.gopaint.listener.InteractListener;
 import net.thenextlvl.gopaint.listener.InventoryListener;
+import net.thenextlvl.gopaint.version.VersionChecker;
 import org.bstats.bukkit.Metrics;
 import org.bukkit.Axis;
 import org.bukkit.Bukkit;
@@ -36,6 +37,7 @@
 import java.io.File;
 import java.util.List;
 import java.util.Locale;
+import java.util.Objects;
 import java.util.Set;
 
 @Accessors(fluent = true)
@@ -68,12 +70,30 @@ public class GoPaintPlugin extends JavaPlugin implements GoPaintProvider {
             .create()
     ).validate().save();
 
+    private final VersionChecker versionChecker = new VersionChecker();
     private final Metrics metrics = new Metrics(this, 22279);
 
     public GoPaintPlugin() {
         registerServices();
     }
 
+    @Override
+    @SuppressWarnings("UnstableApiUsage")
+    public void onLoad() {
+        versionChecker.retrieveLatestSupportedVersion(latest -> latest.ifPresent(version -> {
+            var running = VersionChecker.Version.parse(getPluginMeta().getVersion());
+            if (version.equals(running)) {
+                getComponentLogger().info("You are running the latest version of goPaintAdvanced");
+            } else if (version.compareTo(Objects.requireNonNull(running)) > 0) {
+                getComponentLogger().warn("An update for goPaintAdvanced is available");
+                getComponentLogger().warn("You are running version {}, the latest supported version is {}", running, version);
+                getComponentLogger().warn("Update at https://modrinth.com/plugin/gopaintadvanced or https://hangar.papermc.io/TheNextLvl/goPaintAdvanced");
+            } else {
+                getComponentLogger().warn("You are running a snapshot version of goPaintAdvanced");
+            }
+        }));
+    }
+
     @Override
     public void onEnable() {
         registerListeners();

src/main/java/net/thenextlvl/gopaint/version/VersionChecker.java

@@ -0,0 +1,62 @@
+package net.thenextlvl.gopaint.version;
+
+import me.mrafonso.hangar4j.HangarClient;
+import me.mrafonso.hangar4j.impl.Platform;
+import me.mrafonso.hangar4j.impl.version.HangarVersion;
+import org.bukkit.Bukkit;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Objects;
+import java.util.Optional;
+import java.util.function.Consumer;
+
+public class VersionChecker {
+    private final HangarClient hangarClient = new HangarClient(null);
+
+    public void retrieveLatestSupportedVersion(Consumer<Optional<Version>> success) {
+        Objects.requireNonNull(hangarClient.getVersions("goPaintAdvanced"))
+                .thenAcceptAsync(versions -> success.accept(versions.result().stream()
+                        .filter(this::isSupported)
+                        .map(Version::parse)
+                        .filter(Objects::nonNull)
+                        .max(Version::compareTo)));
+    }
+
+    private boolean isSupported(HangarVersion version) {
+        return version.platformDependencies().get(Platform.PAPER)
+                .contains(Bukkit.getMinecraftVersion());
+    }
+
+    public record Version(int major, int minor, int build) implements Comparable<Version> {
+
+        public static @Nullable Version parse(HangarVersion version) {
+            return parse(version.name());
+        }
+
+        public static @Nullable Version parse(String string) {
+            try {
+                var split = string.split("\\.", 3);
+                return new Version(
+                        Integer.parseInt(split[0]),
+                        Integer.parseInt(split[1]),
+                        Integer.parseInt(split[2])
+                );
+            } catch (Exception ignored) {
+                return null;
+            }
+        }
+
+        @Override
+        public int compareTo(@NotNull Version version) {
+            return major() != version.major() ? Integer.compare(major(), version.major())
+                    : minor() != version.minor() ? Integer.compare(minor(), version.minor())
+                    : Integer.compare(build(), version.build());
+        }
+
+        @Override
+        public String toString() {
+            return major() + "." + minor() + "." + build();
+        }
+    }
+}

src/main/java/net/thenextlvl/gopaint/version/package-info.java

@@ -0,0 +1,10 @@
+@TypesAreNotNullByDefault
+@FieldsAreNotNullByDefault
+@MethodsReturnNotNullByDefault
+@ParametersAreNotNullByDefault
+package net.thenextlvl.gopaint.version;
+
+import core.annotation.FieldsAreNotNullByDefault;
+import core.annotation.MethodsReturnNotNullByDefault;
+import core.annotation.ParametersAreNotNullByDefault;
+import core.annotation.TypesAreNotNullByDefault;