LightNode.Server.ValueProvider.ParseMultipartValue C# (CSharp) Méthode

        void ParseMultipartValue(Stream stream, char[] boundary)
        {
            var state = ReadMultipartState.ReadingBoundary;

            var headerBuffer = new MemoryStream();
            var buffer = new MemoryStream();
            var bufferInReadingBoundary = new MemoryStream();
            var boundaryLength = 0;
            var lastBufferIsString = false;
            string lastName = null;

            int intB;
            while ((intB = stream.ReadByte()) != -1)
            {
                // checking boundary
                var b = (byte)intB;
                if (b == boundary[boundaryLength++])
                {
                    if (boundaryLength == boundary.Length)
                    {
                        // matched, go to next sequence.
                        boundaryLength = 0;
                        bufferInReadingBoundary.Position = 0;
                        state = ReadMultipartState.ReadingHeader;

                        // flush buffer
                        if (buffer.Position != 0)
                        {
                            if (lastName == null) break;

                            var key = lastName;

                            if (lastBufferIsString)
                            {
                                var bytes = buffer.GetBuffer();
                                var value = Encoding.UTF8.GetString(bytes, 0, (int)buffer.Position).Trim('\r', '\n');

                                object result;
                                if (values.TryGetValue(key, out result))
                                {
                                    if (result is string)
                                    {
                                        // second
                                        values[key] = new List<string>() { (string)result, value };
                                    }
                                    else
                                    {
                                        // third
                                        ((List<string>)result).Add(value);
                                    }
                                }
                                else
                                {
                                    // first
                                    values[key] = value;
                                }
                            }
                            else
                            {
                                var bytes = buffer.GetBuffer();
                                var preSkipCount = 0;
                                var postSkipCount = 0;
                                if (bytes.Length > 4)
                                {
                                    if (bytes[0] == '\r')
                                    {
                                        preSkipCount++;
                                        if (bytes[1] == '\n') preSkipCount++;
                                    }
                                    if (bytes[buffer.Position - 1] == '\n')
                                    {
                                        postSkipCount++;
                                        if (bytes[buffer.Position - 2] == '\r') postSkipCount++;
                                    }
                                }

                                var value = new byte[buffer.Position - preSkipCount - postSkipCount];
                                Buffer.BlockCopy(bytes, preSkipCount, value, 0, value.Length);

                                object result;
                                if (values.TryGetValue(key, out result))
                                {
                                    if (result is byte[])
                                    {
                                        // second
                                        values[key] = new List<byte[]>() { (byte[])result, value };
                                    }
                                    else
                                    {
                                        // third
                                        ((List<byte[]>)result).Add(value);
                                    }
                                }
                                else
                                {
                                    // first
                                    values[key] = value;
                                }
                            }

                            lastBufferIsString = false;
                            lastName = null;
                            buffer.Position = 0;
                        }

                        continue;
                    }
                    else
                    {
                        bufferInReadingBoundary.WriteByte(b);
                    }
                    // check new boundary
                    continue;
                }
                else
                {
                    if (bufferInReadingBoundary.Position != 0)
                    {
                        var bufArray = bufferInReadingBoundary.GetBuffer();
                        for (int i = 0; i < bufferInReadingBoundary.Position; i++)
                        {
                            buffer.WriteByte(bufArray[i]);
                        }
                        bufferInReadingBoundary.Position = 0;
                    }

                    boundaryLength = 0;
                }

                if (state == ReadMultipartState.ReadingHeader)
                {
                    // ReadLine
                    headerBuffer.WriteByte(b);

                    bool foundR = false;
                    while ((intB = stream.ReadByte()) != -1)
                    {
                        b = (byte)intB;
                        if (b == '\r')
                        {
                            foundR = true;
                            continue;
                        }
                        else if (foundR && b == '\n')
                        {
                            foundR = false;

                            // finish buffer.
                            var stringBuffer = headerBuffer.GetBuffer();
                            var headerString = Encoding.UTF8.GetString(stringBuffer, 0, (int)headerBuffer.Position).Trim('\r', '\n');

                            if (headerString.StartsWith("Content-Type") && headerString.Contains("text/plain"))
                            {
                                lastBufferIsString = true;
                            }
                            if (headerString.StartsWith("Content-Disposition"))
                            {
                                lastName = nameRegex.Match(headerString).Groups[1].Value;
                                state = ReadMultipartState.ReadingValue;
                            }

                            headerBuffer.Position = 0;
                            break;
                        }

                        headerBuffer.WriteByte(b);
                    }
                }
                else
                {
                    buffer.WriteByte(b);
                }
            }
        }
    }