Implemented Json and MsgPack serializers for path based liveobjects

Author: sacOO7

liveobjects/src/main/kotlin/io/ably/lib/object/serialization/DefaultSerialization.kt

@@ -0,0 +1,44 @@
+package io.ably.lib.`object`.serialization
+
+import com.google.gson.*
+import io.ably.lib.objects.*
+
+import io.ably.lib.objects.ObjectMessage
+import org.msgpack.core.MessagePacker
+import org.msgpack.core.MessageUnpacker
+
+/**
+ * Default implementation of {@link ObjectsSerializer} that handles serialization/deserialization
+ * of ObjectMessage arrays for both JSON and MessagePack formats using Jackson and Gson.
+ * Dynamically loaded by ObjectsHelper#getSerializer() to avoid hard dependencies.
+ */
+@Suppress("unused") // Used via reflection in ObjectsHelper
+internal class DefaultObjectsSerializer : ObjectsSerializer {
+
+  override fun readMsgpackArray(unpacker: MessageUnpacker): Array<Any> {
+    val objectMessagesCount = unpacker.unpackArrayHeader()
+    return Array(objectMessagesCount) { readObjectMessage(unpacker) }
+  }
+
+  override fun writeMsgpackArray(objects: Array<out Any>, packer: MessagePacker) {
+    val objectMessages = objects.map { it as ObjectMessage }
+    packer.packArrayHeader(objectMessages.size)
+    objectMessages.forEach { it.writeMsgpack(packer) }
+  }
+
+  override fun readFromJsonArray(json: JsonArray): Array<Any> {
+    return json.map { element ->
+      if (element.isJsonObject) element.asJsonObject.toObjectMessage()
+      else throw JsonParseException("Expected JsonObject, but found: $element")
+    }.toTypedArray()
+  }
+
+  override fun asJsonArray(objects: Array<out Any>): JsonArray {
+    val objectMessages = objects.map { it as ObjectMessage }
+    val jsonArray = JsonArray()
+    for (objectMessage in objectMessages) {
+      jsonArray.add(objectMessage.toJsonObject())
+    }
+    return jsonArray
+  }
+}

liveobjects/src/main/kotlin/io/ably/lib/object/serialization/JsonSerialization.kt

@@ -0,0 +1,68 @@
+package io.ably.lib.`object`.serialization
+
+import com.google.gson.*
+import io.ably.lib.objects.ObjectsMapSemantics
+import io.ably.lib.objects.ObjectData
+import io.ably.lib.objects.ObjectMessage
+import io.ably.lib.objects.ObjectOperationAction
+import io.ably.lib.objects.serialization.EnumCodeTypeAdapter
+import java.lang.reflect.Type
+import kotlin.enums.EnumEntries
+
+// Gson instance for JSON serialization/deserialization
+internal val gson = GsonBuilder()
+  .registerTypeAdapter(ObjectOperationAction::class.java, EnumCodeTypeAdapter({ it.code }, ObjectOperationAction.entries))
+  .registerTypeAdapter(ObjectsMapSemantics::class.java, EnumCodeTypeAdapter({ it.code }, ObjectsMapSemantics.entries))
+  .create()
+
+internal fun ObjectMessage.toJsonObject(): JsonObject {
+  return gson.toJsonTree(this).asJsonObject
+}
+
+internal fun JsonObject.toObjectMessage(): ObjectMessage {
+  return gson.fromJson(this, ObjectMessage::class.java)
+}
+
+internal class EnumCodeTypeAdapter<T : Enum<T>>(
+  private val getCode: (T) -> Int,
+  private val enumValues: EnumEntries<T>
+) : JsonSerializer<T>, JsonDeserializer<T> {
+
+  override fun serialize(src: T, typeOfSrc: Type, context: JsonSerializationContext): JsonElement {
+    return JsonPrimitive(getCode(src))
+  }
+
+  override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): T {
+    val code = json.asInt
+    return enumValues.firstOrNull { getCode(it) == code } ?: enumValues.firstOrNull { getCode(it) == -1 }
+      ?: throw JsonParseException("Unknown enum code: $code and no Unknown fallback found")
+  }
+}
+
+internal class ObjectDataJsonSerializer : JsonSerializer<ObjectData>, JsonDeserializer<ObjectData> {
+  override fun serialize(src: ObjectData, typeOfSrc: Type?, context: JsonSerializationContext?): JsonElement {
+    val obj = JsonObject()
+    src.objectId?.let { obj.addProperty("objectId", it) }
+    src.string?.let { obj.addProperty("string", it) }
+    src.number?.let { obj.addProperty("number", it) }
+    src.boolean?.let { obj.addProperty("boolean", it) }
+    src.bytes?.let { obj.addProperty("bytes", it) }
+    src.json?.let { obj.addProperty("json", it.toString()) } // Spec: OD4c5
+    return obj
+  }
+
+  override fun deserialize(json: JsonElement, typeOfT: Type?, context: JsonDeserializationContext?): ObjectData {
+    val obj = if (json.isJsonObject) json.asJsonObject else throw JsonParseException("Expected JsonObject")
+    val objectId = if (obj.has("objectId")) obj.get("objectId").asString else null
+    val string = if (obj.has("string")) obj.get("string").asString else null
+    val number = if (obj.has("number")) obj.get("number").asDouble else null
+    val boolean = if (obj.has("boolean")) obj.get("boolean").asBoolean else null
+    val bytes = if (obj.has("bytes")) obj.get("bytes").asString else null
+    val json = if (obj.has("json")) JsonParser.parseString(obj.get("json").asString) else null
+
+    if (objectId == null && string == null && number == null && boolean == null && bytes == null && json == null) {
+      throw JsonParseException("Since objectId is not present, at least one of the value fields must be present")
+    }
+    return ObjectData(objectId = objectId, string = string, number = number, boolean = boolean, bytes = bytes, json = json)
+  }
+}