refactoring: Masive refactor to build the V2

src/main/kotlin/eventDemo/contexts/auth/domain/User.kt

@@ -0,0 +1,39 @@
+package eventDemo.contexts.auth.domain
+
+import eventDemo.contexts.auth.domain.events.NewUserCreatedEvent
+import eventDemo.contexts.auth.domain.events.UserEvent
+import eventDemo.sharedKernel.UserId
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class User(
+  val id: UserId,
+  val username: String,
+  val password: String,
+  val version: Int,
+  val recordedEvents: Set<UserEvent>,
+) {
+  companion object {
+    fun createNewUser(
+      username: String,
+      password: String,
+    ): User =
+      apply(NewUserCreatedEvent(username, password, version = 1))
+
+    fun apply(event: NewUserCreatedEvent): User =
+      User(
+        id = event.aggregateId,
+        username = event.username,
+        password = event.password,
+        version = event.version,
+        recordedEvents = setOf(event),
+      )
+
+    fun loadFromHistory(events: Set<UserEvent>): User? =
+      events.fold(null as User?) { acc, event ->
+        when (event) {
+          is NewUserCreatedEvent -> apply(event)
+        }
+      }
+  }
+}