Paper QOL improvements (#32418)

* Don't add newlines (fixes #32357)

* Improve UI around max paper length (Fixes #32344)

* Display a "fill progress" indicator so users know how close they are to filling it
* Don't allow users to save a paper which went over the limit, to avoid them losing data they want to keep.

---------

Co-authored-by: Eoin Mcloughlin <helloworld@eoinrul.es>

Content.Client/Paper/UI/PaperWindow.xaml.cs

@@ -48,6 +48,20 @@ namespace Content.Client.Paper.UI
 
         public event Action<string>? OnSaved;
 
+        private int _MaxInputLength = -1;
+        public int MaxInputLength
+        {
+            get
+            {
+                return _MaxInputLength;
+            }
+            set
+            {
+                _MaxInputLength = value;
+                UpdateFillState();
+            }
+        }
+
         public PaperWindow()
         {
             IoCManager.InjectDependencies(this);
@@ -63,11 +77,21 @@ namespace Content.Client.Paper.UI
             {
                 if (args.Function == EngineKeyFunctions.MultilineTextSubmit)
                 {
-                    RunOnSaved();
-                    args.Handle();
+                    // SaveButton is disabled when we hit the max input limit. Just check
+                    // that flag instead of trying to calculate the input length again
+                    if (!SaveButton.Disabled)
+                    {
+                        RunOnSaved();
+                        args.Handle();
+                    }
                 }
             };
 
+            Input.OnTextChanged += args =>
+            {
+                UpdateFillState();
+            };
+
             SaveButton.OnPressed += _ =>
             {
                 RunOnSaved();
@@ -126,6 +150,7 @@ namespace Content.Client.Paper.UI
 
             PaperContent.ModulateSelfOverride = visuals.ContentImageModulate;
             WrittenTextLabel.ModulateSelfOverride = visuals.FontAccentColor;
+            FillStatus.ModulateSelfOverride = visuals.FontAccentColor;
 
             var contentImage = visuals.ContentImagePath != null ? _resCache.GetResource<TextureResource>(visuals.ContentImagePath) : null;
             if (contentImage != null)
@@ -296,5 +321,25 @@ namespace Content.Client.Paper.UI
         {
             OnSaved?.Invoke(Rope.Collapse(Input.TextRope));
         }
+
+        private void UpdateFillState()
+        {
+            if (MaxInputLength != -1)
+            {
+                var inputLength = Input.TextLength;
+
+                FillStatus.Text = Loc.GetString("paper-ui-fill-level",
+                    ("currentLength", inputLength),
+                    ("maxLength", MaxInputLength));
+
+                // Disable the save button if we've gone over the limit
+                SaveButton.Disabled = inputLength > MaxInputLength;
+            }
+            else
+            {
+                FillStatus.Text = "";
+                SaveButton.Disabled = false;
+            }
+        }
     }
 }