Reintroduce Node to better model HTML

Ooui/Element.cs

@@ -1,86 +1,13 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
 
 namespace Ooui
 {
-    public class Element
+    public abstract class Element : Node
     {
-        public string Id { get; private set; } = GenerateId ();
+        string className = "";
-
+        public string ClassName {
-        public HtmlMapping Mapping { get; private set; }
+            get => className;
-
+            set => SetProperty (ref className, value);
-        readonly List<Message> messages = new List<Message> ();
-        readonly List<Message> stateMessages = new List<Message> ();
-
-        public Element ()
-        {
-            Mapping = HtmlMapping.Get (GetType ());
-            LogCreate ();
-        }
-
-        protected void Log (Message message)
-        {
-            messages.Add (message);
-
-            switch (message.MessageType) {
-                case MessageType.Create:
-                    stateMessages.Add (message);
-                    break;
-                case MessageType.SetProperty:
-                    {
-                        var old = stateMessages.FirstOrDefault (
-                            x => x.MessageType == MessageType.SetProperty &&
-                                x.Member == message.Member);
-                        if (old != null) {
-                            stateMessages.Remove (old);
-                        }
-                        stateMessages.Add (message);
-                    }
-                    break;
-            }
-        }
-
-        protected void LogCreate ()
-        {
-            Log (new Message {
-                MessageType = MessageType.Create,
-                TargetId = Id,
-                Value = Mapping.TagName,
-            });
-        }
-
-        protected void LogSetProperty (string propertyName, object value)
-        {
-            var m = new Message {
-                MessageType = MessageType.SetProperty,
-                TargetId = Id,
-                Member = Mapping.GetMemberPath (propertyName),
-            };
-            m.SetValue (value);
-            Log (m);
-        }
-
-        protected bool SetProperty<T> (ref T backingStore, T newValue, string propertyName = "")
-        {
-            if (!backingStore.Equals (newValue)) {
-                backingStore = newValue;
-                LogSetProperty (propertyName, newValue);
-                return true;
-            }
-            return false;
-        }
-
-        const string IdChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-        static string GenerateId ()
-        {
-            var rand = new Random();
-            var chars = new char[8];
-            for (var i = 0; i < chars.Length; i++) {
-                chars[i] = IdChars[rand.Next(0, IdChars.Length)];
-            }
-            return new string(chars);
         }
     }
 }

Ooui/Message.cs

@@ -39,11 +39,7 @@ namespace Ooui
     {
         Nop,
         Create,
-        SetProperty,
+        Set,
-    }
+        Call,
-
-    public enum ValueType
-    {
-        String
     }
 }

Ooui/Node.cs

@@ -0,0 +1,130 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Ooui
+{
+    public abstract class Node
+    {
+        public string Id { get; private set; } = GenerateId ();
+
+        public HtmlMapping Mapping { get; private set; }
+
+        readonly List<Node> children = new List<Node> ();
+        readonly List<Message> messages = new List<Message> ();
+        readonly List<Message> stateMessages = new List<Message> ();
+
+        public Node ()
+        {
+            Mapping = HtmlMapping.Get (GetType ());
+            LogCreate ();
+        }
+
+        public Node AppendChild (Node newChild)
+        {
+            return InsertBefore (newChild, null);
+        }
+
+        public Node ParentNode { get; private set; }
+
+        public Node InsertBefore (Node newChild, Node referenceChild)
+        {
+            if (referenceChild == null) {
+                children.Add (newChild);                
+            }
+            else {
+                var index = children.IndexOf (referenceChild);
+                if (index < 0) {
+                    throw new ArgumentException ("Reference must be a child of this element", nameof(referenceChild));
+                }
+                children.Insert (index, newChild);
+            }
+            newChild.ParentNode = this;
+            LogCall ("insertBefore", newChild, referenceChild);
+            return newChild;
+        }
+
+        public Node RemoveChild (Node child)
+        {
+            if (!children.Remove (child)) {
+                throw new ArgumentException ("Child not contained in this element", nameof(child));
+            }
+            child.ParentNode = null;
+            LogCall ("removeChild", child);
+            return child;
+        }
+
+        protected void Log (Message message)
+        {
+            messages.Add (message);
+
+            switch (message.MessageType) {
+                case MessageType.Create:
+                    stateMessages.Add (message);
+                    break;
+                case MessageType.Set:
+                    {
+                        var old = stateMessages.FirstOrDefault (
+                            x => x.MessageType == MessageType.Set &&
+                                x.Member == message.Member);
+                        if (old != null) {
+                            stateMessages.Remove (old);
+                        }
+                        stateMessages.Add (message);
+                    }
+                    break;
+            }
+        }
+
+        protected void LogCreate ()
+        {
+            Log (new Message {
+                MessageType = MessageType.Create,
+                TargetId = Id,
+                Value = Mapping.TagName,
+            });
+        }
+
+        protected void LogCall (string methodName, params object[] args)
+        {
+            Log (new Message {
+                MessageType = MessageType.Call,
+                TargetId = Id,
+                Member = methodName,
+            });
+        }
+
+        protected void LogSet (string propertyName, object value)
+        {
+            var m = new Message {
+                MessageType = MessageType.Set,
+                TargetId = Id,
+                Member = Mapping.GetMemberPath (propertyName),
+            };
+            m.SetValue (value);
+            Log (m);
+        }
+
+        protected bool SetProperty<T> (ref T backingStore, T newValue, string propertyName = "")
+        {
+            if (!backingStore.Equals (newValue)) {
+                backingStore = newValue;
+                LogSet (propertyName, newValue);
+                return true;
+            }
+            return false;
+        }
+
+        const string IdChars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+        static string GenerateId ()
+        {
+            var rand = new Random();
+            var chars = new char[8];
+            for (var i = 0; i < chars.Length; i++) {
+                chars[i] = IdChars[rand.Next(0, IdChars.Length)];
+            }
+            return new string(chars);
+        }
+    }
+}