Implement Fabric platform integration

Author: renvins

common/src/main/java/it/renvins/serverpulse/common/platform/Platform.java

@@ -13,8 +13,11 @@ public interface Platform {
 
     /**
      * Disable the plugin
+     * @throws UnsupportedOperationException if the platform does not support this method
      */
-    void disable();
+    default void disable() {
+        throw new UnsupportedOperationException("This method is not supported on this platform.");
+    }
 
     /**
      * @return true if the current thread is the main thread of the server

fabric/src/main/java/it/renvins/serverpulse/fabric/ServerPulseFabric.java

@@ -2,14 +2,33 @@
 
 import java.util.logging.Logger;
 
+import lombok.Getter;
 import net.fabricmc.api.ModInitializer;
+import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
+import net.minecraft.server.MinecraftServer;
 
 public class ServerPulseFabric implements ModInitializer {
 
     public static final String MOD_ID = "serverpulse";
     public static final Logger LOGGER = Logger.getLogger(MOD_ID);
 
+    @Getter private MinecraftServer server;
+
     @Override
     public void onInitialize() {
+        ServerLifecycleEvents.SERVER_STARTING.register(this::onServerStarting);
+        ServerLifecycleEvents.SERVER_STOPPING.register(this::onServerStopped);
+
+        LOGGER.info("ServerPulse for Fabric initialized - waiting for server starting...");
+    }
+
+    private void onServerStarting(MinecraftServer server) {
+        LOGGER.info("ServerPulse is starting...");
+        this.server = server;
+    }
+
+    private void onServerStopped(MinecraftServer server) {
+        LOGGER.info("ServerPulse is stopping...");
+        this.server = null;
     }
 }

fabric/src/main/java/it/renvins/serverpulse/fabric/platform/FabricPlatform.java

@@ -0,0 +1,46 @@
+package it.renvins.serverpulse.fabric.platform;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import it.renvins.serverpulse.api.data.WorldData;
+import it.renvins.serverpulse.common.platform.Platform;
+import it.renvins.serverpulse.fabric.ServerPulseFabric;
+import lombok.RequiredArgsConstructor;
+import net.fabricmc.fabric.api.networking.v1.PlayerLookup;
+import net.fabricmc.loader.api.FabricLoader;
+import net.minecraft.server.world.ServerWorld;
+
+@RequiredArgsConstructor
+public class FabricPlatform implements Platform {
+
+    private final ServerPulseFabric mod;
+
+    @Override
+    public boolean isEnabled() {
+        return mod.getServer() != null && FabricLoader.getInstance().isModLoaded("serverpulse");
+    }
+
+    @Override
+    public boolean isPrimaryThread() {
+        return mod.getServer().isOnThread();
+    }
+
+    @Override
+    public int getOnlinePlayerCount() {
+        return PlayerLookup.all(mod.getServer()).size();
+    }
+
+    @Override
+    public Map<String, WorldData> getWorldsData() {
+        Map<String, WorldData> worldsData = new HashMap<>();
+        for (ServerWorld world : mod.getServer().getWorlds()) {
+            WorldData worldData = new WorldData(
+                    world.getEntitiesByType(null, entity -> true).size(),
+                    world.getChunkManager().getLoadedChunkCount());
+
+            worldsData.put(world.getRegistryKey().getValue().toString(), worldData);
+        }
+        return worldsData;
+    }
+}