From 2f86598a2a35aed60c21965c160b24bb8c344b62 Mon Sep 17 00:00:00 2001
From: Anton Mukhin <mcfly@mcflyer.ru>
Date: Fri, 30 May 2025 07:15:43 +0300
Subject: [PATCH] WIP: working on a new history class

---
 McBitFont/ChangeHistory.cs | 114 +++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 McBitFont/ChangeHistory.cs

diff --git a/McBitFont/ChangeHistory.cs b/McBitFont/ChangeHistory.cs
new file mode 100644
index 0000000..639b507
--- /dev/null
+++ b/McBitFont/ChangeHistory.cs
@@ -0,0 +1,114 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using static McBitFont.ChangeHistory;
+using static McBitFont.MainForm;
+
+namespace McBitFont {
+    internal class ChangeHistory(int depth = 50) {
+        private List<ChangeEvent> timeline = [];
+        private List<FrameMiniature> canvasChanges = [];
+        private List<List<FrameMiniature>> fontChanges = [];
+        public int Depth { get; set; } = depth;
+        public int Index { get; set; } = -1;
+        public int Count {
+            get { return timeline.Count; }
+        }
+
+        public enum ChangeType {
+            None   = 0,
+            Canvas = 1, // Changes made to canvas
+            Font   = 2  // Symbol width has been changed
+        }
+        public class ChangeEvent(ChangeType type, int index) {
+            public ChangeType Type { get; set; } = type;
+            public int Index { get; set; } = index;
+        }
+
+        private static FrameMiniature CopyFrameSimple(FrameMiniature f) {
+            FrameMiniature newf = new(f.code, f.width, f.height);
+            Array.Copy(f.data, newf.data, f.data.Length);
+            return newf;
+        }
+
+        public void Clear() {
+            timeline.Clear();
+            canvasChanges.Clear();
+            fontChanges.Clear();
+            Index = -1;
+        }
+
+        // Remove oldest event and recalculate indices
+        private bool RemoveOldest() {
+            if (Count == 0) return false;
+            ChangeType ct = timeline.First().Type;
+            
+            switch (ct) {
+                case ChangeType.Canvas:
+                    if (canvasChanges.Count == 0) return false;
+                    canvasChanges.RemoveAt(0);
+                    break;
+                case ChangeType.Font:
+                    if (fontChanges.Count == 0) return false;
+                    fontChanges.RemoveAt(0);
+                    break;
+                default:
+                    return false;
+            }
+            timeline.RemoveAt(0);
+            for (int i = 0; i < Count; i++) {
+                if (timeline[i].Type == ct) timeline[i].Index--;
+            }
+            return true;
+        }
+
+        public bool Remove(bool useIndex = true) {
+            if (Index == -1) return false;
+            var ce = timeline.Last();
+            switch (ce.Type) {
+                case ChangeType.Canvas:
+                    canvasChanges.RemoveAt(ce.Index);
+                    break;
+                case ChangeType.Font:
+                    fontChanges.RemoveAt(ce.Index);
+                    break;
+                default:
+                    return false;
+            }
+            timeline.Remove(ce);
+            if (useIndex) Index--;
+            return true;
+        }
+
+        // Remove history tail
+        private void TruncateTail() {
+            // Check if the Index does not point to the last event
+            if (Index >= 0 && Index < Count - 1) {
+                timeline.RemoveRange(Index + 1, Count - Index - 1);
+            }
+        }
+
+        // Add canvas change
+        public void Add(FrameMiniature f) {
+            TruncateTail();
+
+            canvasChanges.Add(CopyFrameSimple(f));
+            timeline.Add(new ChangeEvent(ChangeType.Canvas, canvasChanges.Count - 1));
+            if (Count > Depth) RemoveOldest();
+            else Index++;
+        }
+
+        // Add Font change
+        public void Add(List<FrameMiniature> ff) {
+            //TruncateTail();
+
+            //fontChanges.Add(CopyFrameSimple(f));
+            //timeline.Add(new ChangeEvent(ChangeType.Canvas, canvasChanges.Count - 1));
+            //if (Count > Depth) RemoveOldest();
+            //else Index++;
+        }
+    }
+}