Merge pull request #21228 from Terochi/recent-messages-implementation

Add ability to view chat send history in input box

osu.Game/Graphics/UserInterface/HistoryTextBox.cs

@@ -0,0 +1,90 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Input.Events;
+using osu.Game.Utils;
+using osuTK.Input;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    /// <summary>
+    /// A <see cref="FocusedTextBox"/> which additionally retains a history of text committed, up to a limit
+    /// (100 by default, specified in constructor).
+    /// The history of committed text can be navigated using up/down arrows.
+    /// This resembles the operation of command-line terminals.
+    /// </summary>
+    public class HistoryTextBox : FocusedTextBox
+    {
+        private readonly LimitedCapacityQueue<string> messageHistory;
+
+        public int HistoryCount => messageHistory.Count;
+
+        private int selectedIndex;
+
+        private string originalMessage = string.Empty;
+
+        /// <summary>
+        /// Creates a new <see cref="HistoryTextBox"/>.
+        /// </summary>
+        /// <param name="capacity">
+        /// The maximum number of committed lines to keep in history.
+        /// When exceeded, the oldest lines in history will be dropped to make space for new ones.
+        /// </param>
+        public HistoryTextBox(int capacity = 100)
+        {
+            messageHistory = new LimitedCapacityQueue<string>(capacity);
+
+            Current.ValueChanged += text =>
+            {
+                if (selectedIndex != HistoryCount && text.NewValue != messageHistory[selectedIndex])
+                {
+                    selectedIndex = HistoryCount;
+                }
+            };
+        }
+
+        protected override bool OnKeyDown(KeyDownEvent e)
+        {
+            switch (e.Key)
+            {
+                case Key.Up:
+                    if (selectedIndex == 0)
+                        return true;
+
+                    if (selectedIndex == HistoryCount)
+                        originalMessage = Text;
+
+                    Text = messageHistory[--selectedIndex];
+
+                    return true;
+
+                case Key.Down:
+                    if (selectedIndex == HistoryCount)
+                        return true;
+
+                    if (selectedIndex == HistoryCount - 1)
+                    {
+                        selectedIndex = HistoryCount;
+                        Text = originalMessage;
+                        return true;
+                    }
+
+                    Text = messageHistory[++selectedIndex];
+
+                    return true;
+            }
+
+            return base.OnKeyDown(e);
+        }
+
+        protected override void Commit()
+        {
+            if (!string.IsNullOrEmpty(Text))
+                messageHistory.Enqueue(Text);
+
+            selectedIndex = HistoryCount;
+
+            base.Commit();
+        }
+    }
+}