Proper deserialization of MinecraftVersionList to keep elements sorted

pandalib-core/src/main/java/fr/pandacube/lib/core/mc_version/MinecraftVersionList.java

@@ -1,5 +1,18 @@
 package fr.pandacube.lib.core.mc_version;
 
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.internal.bind.TreeTypeAdapter;
+import com.google.gson.reflect.TypeToken;
+import fr.pandacube.lib.core.json.Json;
+
+import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -14,6 +27,10 @@ public record MinecraftVersionList(
         Map<String, Integer> protocolOfVersion,
         Map<Integer, List<String>> versionsOfProtocol
 ) {
+    static {
+        Json.registerTypeAdapterFactory(MinecraftVersionListAdapter.FACTORY);
+    }
+
     /**
      * Creates an empty {@link MinecraftVersionList}.
      */
@@ -32,4 +49,35 @@ public record MinecraftVersionList(
         versions.add(versionId);
         versions.sort(MinecraftVersionUtil::compareVersions);
     }
+
+
+    /**
+     * Gson Adapter that ensure the data in {@link MinecraftVersionList} is sorted correctly when deserializing.
+     */
+    public static class MinecraftVersionListAdapter implements JsonSerializer<MinecraftVersionList>, JsonDeserializer<MinecraftVersionList> {
+        public static final TypeAdapterFactory FACTORY = TreeTypeAdapter.newTypeHierarchyFactory(MinecraftVersionList.class, new MinecraftVersionListAdapter());
+
+        private static final TypeToken<Map<String, Integer>> MAP_STR_INT_TYPE = new TypeToken<>() { };
+        private static final TypeToken<Map<Integer, List<String>>> MAP_INT_LIST_STRING_TYPE = new TypeToken<>() { };
+        @Override
+        public MinecraftVersionList deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            if (!(json instanceof JsonObject jsonObj))
+                throw new JsonParseException("Expected JsonObject, got " + json.getClass().getSimpleName() + ".");
+            MinecraftVersionList mvList = new MinecraftVersionList();
+            mvList.protocolOfVersion.putAll(context.deserialize(jsonObj.get("protocolOfVersion"), MAP_STR_INT_TYPE.getType()));
+            mvList.versionsOfProtocol.putAll(context.deserialize(jsonObj.get("versionsOfProtocol"), MAP_INT_LIST_STRING_TYPE.getType()));
+            for (List<String> versionLists : mvList.versionsOfProtocol.values()) {
+                versionLists.sort(MinecraftVersionUtil::compareVersions);
+            }
+            return mvList;
+        }
+
+        @Override
+        public JsonElement serialize(MinecraftVersionList src, Type typeOfSrc, JsonSerializationContext context) {
+            JsonObject obj = new JsonObject();
+            obj.add("protocolOfVersion", context.serialize(src.protocolOfVersion));
+            obj.add("versionsOfProtocol", context.serialize(src.versionsOfProtocol));
+            return obj;
+        }
+    }
 }

pandalib-core/src/main/java/fr/pandacube/lib/core/mc_version/ProtocolVersion.java

@@ -216,6 +216,14 @@ public class ProtocolVersion implements Comparable<ProtocolVersion> {
         return displayOptimizedListOfVersions(List.of(this), finalWordSeparator);
     }
 
+    public String getFirstVersion() {
+        return versions.get(0);
+    }
+
+    public String getLastVersion() {
+        return versions.get(versions.size() - 1);
+    }
+
     @Override
     public boolean equals(Object o) {
         return o instanceof ProtocolVersion pv && protocolVersionNumber == pv.protocolVersionNumber;