feat: Add DocumentService.Client base infrastructure

DocumentService.Client/Extensions/StreamExtensions.cs

@@ -0,0 +1,64 @@
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace DocumentService.Client.Extensions;
+
+/// <summary>
+/// Extension methods for Stream operations.
+/// </summary>
+public static class StreamExtensions
+{
+    /// <summary>
+    /// Converts a stream to a Base64-encoded string.
+    /// </summary>
+    /// <param name="stream">Source stream</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Base64-encoded string</returns>
+    public static async Task<string> ToBase64StringAsync(this Stream stream, CancellationToken cancellationToken = default)
+    {
+        if (stream == null)
+            throw new ArgumentNullException(nameof(stream));
+
+        byte[] bytes = await stream.ToBytesAsync(cancellationToken);
+        return Convert.ToBase64String(bytes);
+    }
+
+    /// <summary>
+    /// Converts a stream to a byte array.
+    /// </summary>
+    /// <param name="stream">Source stream</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Byte array</returns>
+    public static async Task<byte[]> ToBytesAsync(this Stream stream, CancellationToken cancellationToken = default)
+    {
+        if (stream == null)
+            throw new ArgumentNullException(nameof(stream));
+
+        if (stream is MemoryStream ms)
+        {
+            return ms.ToArray();
+        }
+
+        using var memoryStream = new MemoryStream();
+#if NET8_0
+        await stream.CopyToAsync(memoryStream, cancellationToken);
+#else
+        await stream.CopyToAsync(memoryStream);
+#endif
+        return memoryStream.ToArray();
+    }
+
+    /// <summary>
+    /// Resets stream position to beginning if seekable.
+    /// </summary>
+    /// <param name="stream">Stream to reset</param>
+    /// <returns>The same stream (for chaining)</returns>
+    public static Stream Reset(this Stream stream)
+    {
+        if (stream != null && stream.CanSeek)
+            stream.Position = 0;
+
+        return stream!;
+    }
+}