fix: fix update message implementation

Fix update message logic avoiding creation and removal of internal
elements depending on the message and just focusing on updating the
contents of the internal state, and moving the creation of the internal
elements to the constructor of the component.

Closes #47

Author: mlopezFC

src/main/java/com/flowingcode/vaadin/addons/chatassistant/ChatMessage.java

@@ -20,7 +20,6 @@
 package com.flowingcode.vaadin.addons.chatassistant;
 
 import com.flowingcode.vaadin.addons.chatassistant.model.Message;
-import com.flowingcode.vaadin.addons.markdown.BaseMarkdownComponent.DataColorMode;
 import com.flowingcode.vaadin.addons.markdown.MarkdownViewer;
 import com.vaadin.flow.component.Component;
 import com.vaadin.flow.component.HasComponents;
@@ -46,6 +45,7 @@ public class ChatMessage<T extends Message> extends Component implements HasComp
   private T message;
   private boolean markdownEnabled;
   private Div loader;
+  private MarkdownViewer markdownViewer;
 
   /**
    * Creates a new ChatMessage based on the supplied message without markdown support.
@@ -64,6 +64,14 @@ public ChatMessage(T message) {
    */
   public ChatMessage(T message, boolean markdownEnabled) {
     this.markdownEnabled = markdownEnabled;
+    loader = new Div(new Div(),new Div(), new Div(), new Div());
+    loader.setClassName("lds-ellipsis");
+    loader.setVisible(false);
+    this.add(loader);
+    if (markdownEnabled) {
+      markdownViewer = new MarkdownViewer(message.getContent());
+      this.add(markdownViewer);
+    }
     setMessage(message);
   }
 
@@ -87,21 +95,17 @@ public void setMessage(T message) {
     }
   }
 
+  /**
+   * Updates the displayed message content and loading state.
+   * @param message
+   */
   private void updateMessage(T message) {
-    if (message.isLoading()) {
-      loader = new Div(new Div(),new Div(), new Div(), new Div());
-      loader.setClassName("lds-ellipsis");
-      this.add(loader);
-    } else {
-      if (loader!=null) {
-        this.remove(loader);
-        loader = null;
-      }
+    loader.setVisible(message.isLoading());
+    if (!message.isLoading()) {
       if (markdownEnabled) {
-        MarkdownViewer mdv = new MarkdownViewer(message.getContent());
-        mdv.setDataColorMode(DataColorMode.LIGHT);
-        this.add(mdv);
+        markdownViewer.setContent(message.getContent());
       } else {
+        this.getElement().executeJs("[...this.childNodes].forEach(node => node.nodeType === 3 && this.removeChild(node));");
         this.getElement().executeJs("this.appendChild(document.createTextNode($0));", message.getContent());
       }
     }