Add possibility to get the supported versions from the api and status response (#402)

* Possibility  to send the Supported versions inside the status response packet

* Make lowercase

src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java

@@ -33,10 +33,7 @@ import us.myles.ViaVersion.util.ReflectionUtil;
 import java.io.File;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.UUID;
+import java.util.*;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Future;
@@ -96,6 +93,7 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
                         getLogger().warning("ViaVersion will not function on the current protocol.");
                     }
                 }
+                ProtocolRegistry.refreshVersions();
             }
         });
 
@@ -363,6 +361,11 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
         return compatSpigotBuild;
     }
 
+    @Override
+    public SortedSet<Integer> getSupportedVersions() {
+        return ProtocolRegistry.getSupportedVersions();
+    }
+
     public boolean isCheckForUpdates() {
         return getConfig().getBoolean("checkforupdates", true);
     }
@@ -447,6 +450,11 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI, ViaVe
         return getConfig().getBoolean("anti-xray-patch", true);
     }
 
+    @Override
+    public boolean isSendSupportedVersions() {
+        return getConfig().getBoolean("send-supported-versions", false);
+    }
+
     public boolean isAutoTeam() {
         // Collision has to be enabled first
         return isPreventCollision() && getConfig().getBoolean("auto-team", true);

src/main/java/us/myles/ViaVersion/api/ViaVersionAPI.java

@@ -7,6 +7,7 @@ import us.myles.ViaVersion.api.boss.BossColor;
 import us.myles.ViaVersion.api.boss.BossStyle;
 import us.myles.ViaVersion.api.command.ViaVersionCommand;
 
+import java.util.SortedSet;
 import java.util.UUID;
 
 public interface ViaVersionAPI {
@@ -109,4 +110,11 @@ public interface ViaVersionAPI {
      * @return True if it is
      */
     boolean isCompatSpigotBuild();
+
+    /**
+     * Get the supported protocol versions
+     *
+     * @return a list of protocol versions
+     */
+    SortedSet<Integer> getSupportedVersions();
 }

src/main/java/us/myles/ViaVersion/api/ViaVersionConfig.java

@@ -149,4 +149,11 @@ public interface ViaVersionConfig {
      * @return A boolean
      */
     boolean isAntiXRay();
+
+    /**
+     * Send supported versions in the status response packet
+     *
+     * @return If true, enabled
+     */
+    boolean isSendSupportedVersions();
 }

src/main/java/us/myles/ViaVersion/api/protocol/ProtocolRegistry.java

@@ -1,5 +1,7 @@
 package us.myles.ViaVersion.api.protocol;
 
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
 import org.bukkit.Bukkit;
 import us.myles.ViaVersion.api.Pair;
 import us.myles.ViaVersion.protocols.base.BaseProtocol;
@@ -10,14 +12,16 @@ import us.myles.ViaVersion.protocols.protocol1_9to1_8.Protocol1_9TO1_8;
 import us.myles.ViaVersion.protocols.protocol1_9to1_9_1.Protocol1_9TO1_9_1;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class ProtocolRegistry {
+    public static final Protocol BASE_PROTOCOL = new BaseProtocol();
     public static int SERVER_PROTOCOL = -1;
     // Input Version -> Output Version & Protocol (Allows fast lookup)
-    private static Map<Integer, Map<Integer, Protocol>> registryMap = new HashMap<>();
-    private static Map<Pair<Integer, Integer>, List<Pair<Integer, Protocol>>> pathCache = new HashMap<>();
-    private static List<Protocol> registerList = new ArrayList<>();
-    public static final Protocol BASE_PROTOCOL = new BaseProtocol();
+    private static Map<Integer, Map<Integer, Protocol>> registryMap = new ConcurrentHashMap<>();
+    private static Map<Pair<Integer, Integer>, List<Pair<Integer, Protocol>>> pathCache = new ConcurrentHashMap<>();
+    private static List<Protocol> registerList = Lists.newCopyOnWriteArrayList();
+    private static Set<Integer> supportedVersions = Sets.newConcurrentHashSet();
 
     static {
         // Base Protocol
@@ -29,7 +33,6 @@ public class ProtocolRegistry {
         // Only supported for 1.9.4 server to 1.9 (nothing else)
         registerProtocol(new Protocol1_9TO1_9_1(), Arrays.asList(ProtocolVersion.v1_9.getId()), ProtocolVersion.v1_9_2.getId());
         registerProtocol(new Protocol1_9_1_2TO1_9_3(), Arrays.asList(ProtocolVersion.v1_9_1.getId(), ProtocolVersion.v1_9_2.getId()), ProtocolVersion.v1_9_3.getId());
-
     }
 
     /**
@@ -54,11 +57,29 @@ public class ProtocolRegistry {
 
         if (Bukkit.getPluginManager().getPlugin("ViaVersion").isEnabled()) {
             protocol.registerListeners();
+            refreshVersions();
         } else {
             registerList.add(protocol);
         }
     }
 
+    public static void refreshVersions() {
+        supportedVersions.clear();
+
+        supportedVersions.add(ProtocolRegistry.SERVER_PROTOCOL);
+        for (ProtocolVersion versions : ProtocolVersion.getProtocols()) {
+            List<Pair<Integer, Protocol>> paths = getProtocolPath(versions.getId(), ProtocolRegistry.SERVER_PROTOCOL);
+            if (paths == null) continue;
+            supportedVersions.add(versions.getId());
+            for (Pair<Integer, Protocol> path : paths)
+                supportedVersions.add(path.getKey());
+        }
+    }
+
+    public static SortedSet<Integer> getSupportedVersions() {
+        return Collections.unmodifiableSortedSet(new TreeSet<>(supportedVersions));
+    }
+
     /**
      * Check if this plugin is useful to the server.
      *
@@ -90,7 +111,7 @@ public class ProtocolRegistry {
      * @return The path which has been generated, null if failed.
      */
     private static List<Pair<Integer, Protocol>> getProtocolPath(List<Pair<Integer, Protocol>> current, int clientVersion, int serverVersion) {
-        if(clientVersion == serverVersion) return null; // We're already there
+        if (clientVersion == serverVersion) return null; // We're already there
         if (current.size() > 50) return null; // Fail safe, protocol too complicated.
 
         // First check if there is any protocols for this

src/main/java/us/myles/ViaVersion/protocols/base/BaseProtocol.java

@@ -42,6 +42,8 @@ public class BaseProtocol extends Protocol {
                         try {
                             JSONObject json = (JSONObject) new JSONParser().parse(originalStatus);
                             JSONObject version = (JSONObject) json.get("version");
+                            if (ViaVersion.getConfig().isSendSupportedVersions())
+                                version.put("supportedVersions", ViaVersion.getInstance().getSupportedVersions());
                             if (ProtocolRegistry.SERVER_PROTOCOL == -1) {
                                 Long original = (Long) version.get("protocol");
                                 ProtocolRegistry.SERVER_PROTOCOL = original.intValue();

src/main/resources/config.yml

@@ -54,3 +54,5 @@ tracking-max-warnings: 4
 tracking-max-kick-msg: "You are sending too many packets, :("
 # Patch the Anti xray to work on 1.9 (If your server is 1.8) This can cost more performance, so disable it if you don't use it.
 anti-xray-patch: true
+# Send the supported versions with the Status response packet
+send-supported-versions: false