Make plugin channel mappings modifiable

common/src/main/java/us/myles/ViaVersion/api/data/MappingDataLoader.java

@@ -1,20 +1,41 @@
 package us.myles.ViaVersion.api.data;
 
-import com.google.gson.JsonArray;
+import com.google.gson.*;
-import com.google.gson.JsonElement;
-import com.google.gson.JsonObject;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.util.GsonUtil;
 
-import java.io.IOException;
+import java.io.*;
-import java.io.InputStream;
+import java.nio.file.Files;
-import java.io.InputStreamReader;
 import java.util.Map;
 
 public class MappingDataLoader {
 
+    public static JsonObject loadFromDataDir(String name) {
+        File file = new File(Via.getPlatform().getDataFolder(), name);
+        if (!file.exists()) {
+            try (InputStream in = getResource(name)) {
+                Files.copy(in, file.toPath());
+            } catch (IOException e) {
+                Via.getPlatform().getLogger().warning("Error loading " + name + " from the config directory!");
+                e.printStackTrace();
+                return null;
+            }
+        }
+
+        try (FileReader reader = new FileReader(file)) {
+            return GsonUtil.getGson().fromJson(reader, JsonObject.class);
+        } catch (IOException e) {
+            e.printStackTrace();
+            return null;
+        } catch (JsonSyntaxException | JsonIOException e) {
+            Via.getPlatform().getLogger().warning(name + " is badly formatted!");
+            e.printStackTrace();
+            return null;
+        }
+    }
+
     public static JsonObject loadData(String name) {
-        InputStream stream = MappingDataLoader.class.getClassLoader().getResourceAsStream("assets/viaversion/data/" + name);
+        InputStream stream = getResource(name);
         InputStreamReader reader = new InputStreamReader(stream);
         try {
             return GsonUtil.getGson().fromJson(reader, JsonObject.class);
@@ -107,4 +128,8 @@ public class MappingDataLoader {
         }
         return null;
     }
+
+    private static InputStream getResource(String name) {
+        return MappingDataLoader.class.getClassLoader().getResourceAsStream("assets/viaversion/data/" + name);
+    }
 }

common/src/main/java/us/myles/ViaVersion/api/platform/ViaPlatform.java

@@ -6,6 +6,7 @@ import us.myles.ViaVersion.api.ViaVersionConfig;
 import us.myles.ViaVersion.api.command.ViaCommandSender;
 import us.myles.ViaVersion.api.configuration.ConfigurationProvider;
 
+import java.io.File;
 import java.util.UUID;
 import java.util.logging.Logger;
 
@@ -139,6 +140,13 @@ public interface ViaPlatform<T> {
      */
     ConfigurationProvider getConfigurationProvider();
 
+    /**
+     * Get ViaVersions's data folder.
+     *
+     * @return data folder
+     */
+    File getDataFolder();
+
     /**
      * Called when a reload happens
      */

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/data/MappingData.java

@@ -27,6 +27,7 @@ public class MappingData {
     public static final BiMap<Short, String> oldEnchantmentsIds = HashBiMap.create();
     public static final Map<String, String> translateMapping = new HashMap<>();
     public static final Map<String, String> mojangTranslation = new HashMap<>();
+    public static final BiMap<String, String> channelMappings = HashBiMap.create(); // 1.12->1.13
     public static Mappings enchantmentMappings;
     public static Mappings soundMappings;
     public static Mappings blockMappings;
@@ -48,6 +49,21 @@ public class MappingData {
         enchantmentMappings = new Mappings(72, mapping1_12.getAsJsonObject("enchantments"), mapping1_13.getAsJsonObject("enchantments"));
         Via.getPlatform().getLogger().info("Loading 1.12.2 -> 1.13 sound mapping...");
         soundMappings = new Mappings(662, mapping1_12.getAsJsonArray("sounds"), mapping1_13.getAsJsonArray("sounds"));
+        Via.getPlatform().getLogger().info("Loading 1.12.2 -> 1.13 plugin channel mappings...");
+
+        JsonObject object = MappingDataLoader.loadFromDataDir("channelmappings-1.13.json");
+        if (object != null) {
+            for (Map.Entry<String, JsonElement> entry : object.entrySet()) {
+                String oldChannel = entry.getKey();
+                String newChannel = entry.getValue().getAsString();
+                if (!isValid1_13Channel(newChannel)) {
+                    Via.getPlatform().getLogger().warning("Channel '" + newChannel + "' is not a valid 1.13 plugin channel, please check your configuration!");
+                    continue;
+                }
+                channelMappings.put(oldChannel, newChannel);
+            }
+        }
+
         Via.getPlatform().getLogger().info("Loading translation mappping");
         Map<String, String> translateData = GsonUtil.getGson().fromJson(
                 new InputStreamReader(MappingData.class.getClassLoader().getResourceAsStream("assets/viaversion/data/mapping-lang-1.12-1.13.json")),
@@ -79,6 +95,22 @@ public class MappingData {
         }
     }
 
+    public static String validateNewChannel(String newId) {
+        if (!isValid1_13Channel(newId)) {
+            return null; // Not valid
+        }
+        int separatorIndex = newId.indexOf(':');
+        // Vanilla parses ``:`` and ```` as ``minecraft:`` (also ensure there's enough space)
+        if ((separatorIndex == -1 || separatorIndex == 0) && newId.length() <= 10) {
+            newId = "minecraft:" + newId;
+        }
+        return newId;
+    }
+
+    public static boolean isValid1_13Channel(String channelId) {
+        return channelId.matches("([0-9a-z_.-]+):([0-9a-z_/.-]+)");
+    }
+
     private static void loadTags(Map<String, Integer[]> output, JsonObject newTags) {
         for (Map.Entry<String, JsonElement> entry : newTags.entrySet()) {
             JsonArray ids = entry.getValue().getAsJsonArray();

common/src/main/java/us/myles/ViaVersion/protocols/protocol1_13to1_12_2/packets/InventoryPackets.java

@@ -443,6 +443,7 @@ public class InventoryPackets {
     }
 
     public static String getNewPluginChannelId(String old) {
+        // Default channels that should not be modifiable
         switch (old) {
             case "MC|TrList":
                 return "minecraft:trader_list";
@@ -460,21 +461,12 @@ public class InventoryPackets {
                 return "minecraft:unregister";
             case "BungeeCord":
                 return "bungeecord:main";
-            case "WDL|INIT":
-                return "wdl:init";
-            case "WDL|CONTROL":
-                return "wdl:control";
-            case "WDL|REQUEST":
-                return "wdl:request";
             case "bungeecord:main":
                 return null;
-            case "FML|MP":
-                return "fml:mp";
-            case "FML|HS":
-                return "fml:hs";
             default:
-                return old.matches("([0-9a-z_.-]+):([0-9a-z_/.-]+)") // Identifier regex
+                String mappedChannel = MappingData.channelMappings.get(old);
-                        ? old : null;
+                if (mappedChannel != null) return mappedChannel;
+                return MappingData.isValid1_13Channel(old) ? old : null;
         }
     }
 
@@ -682,31 +674,11 @@ public class InventoryPackets {
     }
 
     public static String getOldPluginChannelId(String newId) {
-        if (!newId.matches("([0-9a-z_.-]+):([0-9a-z_/.-]+)")) {
+        newId = MappingData.validateNewChannel(newId);
-            return null; // Not valid
+        if (newId == null) return null;
-        }
+
-        int separatorIndex = newId.indexOf(':');
+        // Default channels that should not be modifiable
-        // Vanilla parses ``:`` and ```` as ``minecraft:`` (also ensure there's enough space)
-        if ((separatorIndex == -1 || separatorIndex == 0) && newId.length() <= 10) {
-            newId = "minecraft:" + newId;
-        }
         switch (newId) {
-            case "minecraft:trader_list":
-                return "MC|TrList";
-            case "minecraft:book_open":
-                return "MC|BOpen";
-            case "minecraft:debug/paths":
-                return "MC|DebugPath";
-            case "minecraft:debug/neighbors_update":
-                return "MC|DebugNeighborsUpdate";
-            case "minecraft:register":
-                return "REGISTER";
-            case "minecraft:unregister":
-                return "UNREGISTER";
-            case "minecraft:brand":
-                return "MC|Brand";
-            case "bungeecord:main":
-                return "BungeeCord";
             case "wdl:init":
                 return "WDL|INIT";
             case "wdl:control":
@@ -718,6 +690,8 @@ public class InventoryPackets {
             case "fml:mp":
                 return "FML:MP";
             default:
+                String mappedChannel = MappingData.channelMappings.inverse().get(newId);
+                if (mappedChannel != null) return mappedChannel;
                 return newId.length() > 20 ? newId.substring(0, 20) : newId;
         }
     }

common/src/main/resources/assets/viaversion/data/channelmappings-1.13.json

@@ -0,0 +1,7 @@
+{
+  "WDL|INIT": "wdl:init",
+  "WDL|CONTROL": "wdl:control",
+  "WDL|REQUEST": "wdl:request",
+  "FML|MP": "fml:mp",
+  "FML|HS": "fml:hs"
+}

sponge/src/main/java/us/myles/ViaVersion/SpongePlugin.java

@@ -195,6 +195,11 @@ public class SpongePlugin implements ViaPlatform {
         return conf;
     }
 
+    @Override
+    public File getDataFolder() {
+        return defaultConfig.getParentFile();
+    }
+
     @Override
     public void onReload() {
         getLogger().severe("ViaVersion is already loaded, this should work fine. If you get any console errors, try rebooting.");

velocity/src/main/java/us/myles/ViaVersion/VelocityPlugin.java

@@ -30,6 +30,7 @@ import us.myles.ViaVersion.velocity.platform.*;
 import us.myles.ViaVersion.velocity.service.ProtocolDetectorService;
 import us.myles.ViaVersion.velocity.util.LoggerWrapper;
 
+import java.io.File;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
@@ -176,6 +177,11 @@ public class VelocityPlugin implements ViaPlatform<Player> {
         return conf;
     }
 
+    @Override
+    public File getDataFolder() {
+        return configDir.toFile();
+    }
+
     @Override
     public void onReload() {