Create WireMock.Net.MimePart project (#1300)

* Create WireMock.Net.MimePart project

* .

* REFACTOR

* ILRepack

* --

* ...

* x

* x

* .

* fix

* public class MimePartMatcher

* shared

* min

* .

* <!--<DelaySign>true</DelaySign>-->

* Update README.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

src/WireMock.Net.MimePart/Util/MimeKitUtils.cs

@@ -0,0 +1,84 @@
+// Copyright © WireMock.Net
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Linq;
+using System.Text;
+using MimeKit;
+using Stef.Validation;
+using WireMock.Http;
+using WireMock.Types;
+
+namespace WireMock.Util;
+
+internal class MimeKitUtils : IMimeKitUtils
+{
+    /// <inheritdoc />
+    public object LoadFromStream(Stream stream)
+    {
+        return MimeMessage.Load(Guard.NotNull(stream));
+    }
+
+    /// <inheritdoc />
+    public bool TryGetMimeMessage(IRequestMessage requestMessage, [NotNullWhen(true)] out object? mimeMessage)
+    {
+        Guard.NotNull(requestMessage);
+
+        if (requestMessage.BodyData != null &&
+            requestMessage.Headers?.TryGetValue(HttpKnownHeaderNames.ContentType, out var contentTypeHeader) == true &&
+            StartsWithMultiPart(contentTypeHeader) // Only parse when "multipart/mixed"
+        )
+        {
+            var bytes = requestMessage.BodyData?.DetectedBodyType switch
+            {
+                // If the body is bytes, use the BodyAsBytes to match on.
+                BodyType.Bytes => requestMessage.BodyData.BodyAsBytes!,
+
+                // If the body is a String or MultiPart, use the BodyAsString to match on.
+                BodyType.String or BodyType.MultiPart => Encoding.UTF8.GetBytes(requestMessage.BodyData.BodyAsString!),
+
+                _ => throw new NotSupportedException()
+            };
+
+            var fixedBytes = FixBytes(bytes, contentTypeHeader[0]);
+
+            mimeMessage = LoadFromStream(new MemoryStream(fixedBytes));
+            return true;
+        }
+
+        mimeMessage = null;
+        return false;
+    }
+
+    /// <inheritdoc />
+    public IReadOnlyList<object> GetBodyParts(object mimeMessage)
+    {
+        if (mimeMessage is not MimeMessage mm)
+        {
+            throw new ArgumentException($"The mimeMessage must be of type {nameof(MimeMessage)}", nameof(mimeMessage));
+        }
+
+        return mm.BodyParts
+            .OfType<MimePart>()
+            .ToArray();
+    }
+
+    private static bool StartsWithMultiPart(WireMockList<string> contentTypeHeader)
+    {
+        return contentTypeHeader.Any(ct => ct.TrimStart().StartsWith("multipart/", StringComparison.OrdinalIgnoreCase));
+    }
+
+    private static byte[] FixBytes(byte[] bytes, WireMockList<string> contentType)
+    {
+        var contentTypeBytes = Encoding.UTF8.GetBytes($"{HttpKnownHeaderNames.ContentType}: {contentType}\r\n\r\n");
+
+        var result = new byte[contentTypeBytes.Length + bytes.Length];
+
+        Buffer.BlockCopy(contentTypeBytes, 0, result, 0, contentTypeBytes.Length);
+        Buffer.BlockCopy(bytes, 0, result, contentTypeBytes.Length, bytes.Length);
+
+        return result;
+    }
+}