Initial commit.

PerfectNumbers.Core/TextFileWriter.cs

@@ -0,0 +1,77 @@
+namespace PerfectNumbers.Core;
+
+/// <summary>
+/// Provides thread-safe file writing for both text and binary data.
+/// </summary>
+public sealed class TextFileWriter : IDisposable
+{
+    private readonly FileStream _stream;
+    private StreamWriter? _textWriter;
+    private BinaryWriter? _binaryWriter;
+    private readonly object _lock = new();
+
+    public TextFileWriter(string path, FileMode mode)
+    {
+        var options = new FileStreamOptions
+        {
+            Access = FileAccess.Write,
+            Mode = mode,
+            Share = FileShare.Read
+        };
+        _stream = new FileStream(path, options);
+    }
+
+    public long Position
+    {
+        get { lock (_lock) { return _stream.Position; } }
+    }
+
+    private StreamWriter TextWriter => _textWriter ??= new StreamWriter(_stream, leaveOpen: true);
+    private BinaryWriter BinaryWriter => _binaryWriter ??= new BinaryWriter(_stream, System.Text.Encoding.UTF8, leaveOpen: true);
+
+    /// <summary>
+    /// Clears the file by truncating it to zero length.
+    /// </summary>
+    public void Clear()
+    {
+        lock (_lock)
+        {
+            _stream.SetLength(0);
+            _stream.Position = 0;
+            _textWriter?.Flush();
+            _binaryWriter?.Flush();
+        }
+    }
+
+    /// <summary>
+    /// Writes a line of text to the file.
+    /// </summary>
+    public void WriteLine(string line)
+    {
+        lock (_lock)
+        {
+            TextWriter.WriteLine(line);
+            TextWriter.Flush();
+        }
+    }
+
+    /// <summary>
+    /// Executes a binary writing action within the internal lock.
+    /// </summary>
+    public void WriteBinary(Action<BinaryWriter> action)
+    {
+        lock (_lock)
+        {
+            action(BinaryWriter);
+            BinaryWriter.Flush();
+        }
+    }
+
+    public void Dispose()
+    {
+        _binaryWriter?.Dispose();
+        _textWriter?.Dispose();
+        _stream.Dispose();
+    }
+}
+