feat: implement virtual content management for large files in TabInfo

Author: chemodun

TabInfo.cs

@@ -1,5 +1,6 @@
 using System;
 using System.ComponentModel;
+using System.IO;
 using System.Text.Json.Serialization;
 using System.Text.RegularExpressions;
 using System.Windows;
@@ -133,6 +134,13 @@ public bool HasNewContent
     // Validation state
     public bool IsRegexValid { get; private set; }
 
+    // Virtual content management for large files
+    private readonly string? _tempFilePath;
+    private long _totalContentLength;
+    private const long MAX_MEMORY_CONTENT = 25_000_000; // 25MB in memory
+    private const long KEEP_RECENT_CONTENT = 5_000_000; // Keep last 5MB in memory
+    private bool _isUsingDiskStorage = false;
+
     /// <summary>
     /// Creates a new TabInfo with references to all controls
     /// </summary>
@@ -163,6 +171,11 @@ public TabInfo(
       AfterLinesCurrent = 0;
       IsAutoCreated = isAutoCreated;
 
+      // Initialize virtual content management
+      _tempFilePath = System.IO.Path.Combine(System.IO.Path.GetTempPath(), $"X4LogWatcher_Tab_{Guid.NewGuid():N}.tmp");
+      _totalContentLength = 0;
+      _isUsingDiskStorage = false;
+
       // Wire up events
       RegexTextBox.TextChanged += RegexTextBox_TextChanged;
 
@@ -308,6 +321,9 @@ public void AppendContent(string text)
 
       ContentTextBox.AppendText(text);
       ContentTextBox.ScrollToEnd();
+
+      // Check if we need to optimize memory after adding content
+      OptimizeMemoryIfNeeded();
     }
 
     /// <summary>
@@ -339,6 +355,102 @@ private void UpdateNewContentIndicator()
       UpdateTabHeader();
     }
 
+    /// <summary>
+    /// Get estimated memory usage of this tab's content
+    /// </summary>
+    /// <returns>Estimated memory usage in bytes</returns>
+    public long GetEstimatedMemoryUsage()
+    {
+      if (_disposed)
+        return 0;
+
+      try
+      {
+        // Estimate memory usage: string content + UI overhead
+        var textLength = ContentTextBox?.Text?.Length ?? 0;
+        return textLength * 2; // Unicode characters are 2 bytes each
+      }
+      catch
+      {
+        return 0;
+      }
+    }
+
+    /// <summary>
+    /// Optimize memory usage by moving old content to disk if needed
+    /// </summary>
+    public void OptimizeMemoryIfNeeded()
+    {
+      if (_disposed || ContentTextBox == null)
+        return;
+
+      try
+      {
+        var currentLength = ContentTextBox.Text.Length;
+
+        if (currentLength > MAX_MEMORY_CONTENT)
+        {
+          // Keep only the most recent content in memory
+          var text = ContentTextBox.Text;
+          var keepFromIndex = Math.Max(0, currentLength - (int)KEEP_RECENT_CONTENT);
+
+          // Find a good line boundary to cut at
+          var cutIndex = text.LastIndexOf('\n', keepFromIndex);
+          if (cutIndex < 0)
+            cutIndex = keepFromIndex;
+
+          var oldContent = text.Substring(0, cutIndex);
+          var recentContent = text.Substring(cutIndex);
+
+          // Save old content to disk if we have a temp file path
+          if (!string.IsNullOrEmpty(_tempFilePath))
+          {
+            File.AppendAllText(_tempFilePath, oldContent);
+            _isUsingDiskStorage = true;
+          }
+
+          // Keep only recent content in memory
+          ContentTextBox.Text = recentContent;
+          _totalContentLength += oldContent.Length;
+
+          System.Diagnostics.Debug.WriteLine(
+            $"Tab '{TabName}' optimized: moved {oldContent.Length} chars to disk, kept {recentContent.Length} in memory"
+          );
+        }
+      }
+      catch (Exception ex)
+      {
+        System.Diagnostics.Debug.WriteLine($"Error optimizing memory for tab '{TabName}': {ex.Message}");
+      }
+    }
+
+    /// <summary>
+    /// Get the full content including disk-stored content (expensive operation)
+    /// </summary>
+    public string GetFullContent()
+    {
+      if (_disposed)
+        return string.Empty;
+
+      try
+      {
+        var memoryContent = ContentTextBox?.Text ?? string.Empty;
+
+        if (_isUsingDiskStorage && !string.IsNullOrEmpty(_tempFilePath) && File.Exists(_tempFilePath))
+        {
+          var diskContent = File.ReadAllText(_tempFilePath);
+          return diskContent + memoryContent;
+        }
+
+        return memoryContent;
+      }
+      catch (Exception ex)
+      {
+        System.Diagnostics.Debug.WriteLine($"Error reading full content for tab '{TabName}': {ex.Message}");
+        return ContentTextBox?.Text ?? string.Empty;
+      }
+    }
+
     #region IDisposable Implementation
 
     /// <summary>
@@ -389,6 +501,22 @@ protected virtual void Dispose(bool disposing)
           {
             ContentTextBox.Clear();
           }
+
+          // Clean up temporary file if it exists
+          if (_isUsingDiskStorage && !string.IsNullOrEmpty(_tempFilePath))
+          {
+            try
+            {
+              if (File.Exists(_tempFilePath))
+              {
+                File.Delete(_tempFilePath);
+              }
+            }
+            catch (Exception deleteEx)
+            {
+              System.Diagnostics.Debug.WriteLine($"Error deleting temp file {_tempFilePath}: {deleteEx.Message}");
+            }
+          }
         }
         catch (Exception ex)
         {