ng-flow asp.net api2 upload class

UploadController.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Runtime.Serialization;
using System.Threading.Tasks;
using System.Web;
using System.Web.Http;
using System.Web.Http.Cors;
using System.Web.Mvc;

namespace WHOUploadSPA.Controllers
{
    
    [DataContract]
    public class FileDesc
    {
        [DataMember]
        public string name { get; set; }
        [DataMember]
        public string path { get; set; }
        [DataMember]
        public long size { get; set; }
        public FileDesc(string n, string p, long s)
        {
            name = n;
            path = p;
            size = s;
        }
    }

    public class CustomMultipartFormDataStreamProvider : MultipartFormDataStreamProvider
    {
        public readonly string _filename;
        public CustomMultipartFormDataStreamProvider(string path, string filename) : base(path)
        {
            _filename = filename;
        }
 
        public override string GetLocalFileName(System.Net.Http.Headers.HttpContentHeaders headers)
        {
            return _filename;
        }
    }
    

    [EnableCors("*", "*", "GET, PUT, POST")]
    public class UploadController : ApiController
    {
        private readonly string BASEFOLDERNAME = "uploads";
        private class FlowMeta
    {
        public string flowChunkNumber { get; set; }
        public string flowChunkSize { get; set; }
        public string flowCurrentChunkSize { get; set; }
        public string flowTotalSize { get; set; }
        public string flowIdentifier { get; set; }
        public string flowFilename { get; set; }
        public string flowRelativePath { get; set; }
        public string flowTotalChunks { get; set; }

        public FlowMeta(Dictionary<string, string> values)
        {
            flowChunkNumber = values["flowChunkNumber"];
            flowChunkSize = values["flowChunkSize"];
            flowCurrentChunkSize = values["flowCurrentChunkSize"];
            flowTotalSize = values["flowTotalSize"];
            flowIdentifier = values["flowIdentifier"];
            flowFilename = values["flowFilename"];
            flowRelativePath = values["flowRelativePath"];
            flowTotalChunks = values["flowTotalChunks"];
        }

        public FlowMeta(NameValueCollection values)
        {
            flowChunkNumber = values["flowChunkNumber"];
            flowChunkSize = values["flowChunkSize"];
            flowCurrentChunkSize = values["flowCurrentChunkSize"];
            flowTotalSize = values["flowTotalSize"];
            flowIdentifier = values["flowIdentifier"];
            flowFilename = values["flowFilename"];
            flowRelativePath = values["flowRelativePath"];
            flowTotalChunks = values["flowTotalChunks"];
        }
    }


        public HttpResponseMessage Get()
        {
            var meta = new FlowMeta(Request.GetQueryNameValuePairs().ToDictionary(x => x.Key, x => x.Value));
            var PATH = HttpContext.Current.Server.MapPath(string.Format(@"~/{0}/{1}", BASEFOLDERNAME, meta.flowIdentifier));
            var filename = string.Format(@"{0}_{1}", meta.flowFilename, meta.flowChunkNumber.PadLeft(4, '0'));
            if ("1".Equals(meta.flowTotalChunks))
            {
                filename = string.Format(@"{0}", meta.flowFilename);
            }
            if (File.Exists(Path.Combine(PATH, filename)))
            {
                return Request.CreateResponse(HttpStatusCode.OK);
            }
            else
            {
                return Request.CreateResponse(HttpStatusCode.NotFound);
            }
        }
    
        public Task<IEnumerable<FileDesc>> Post()
        {
            var meta = new FlowMeta(HttpContext.Current.Request.Form);
            var PATH = HttpContext.Current.Server.MapPath(string.Format(@"~/{0}/{1}", BASEFOLDERNAME, meta.flowIdentifier));
            var variables = System.Web.HttpContext.Current.Request.ServerVariables;
            var physPath = variables["APPL_PHYSICAL_PATH"];
          
            Directory.CreateDirectory(PATH);
            var rootUrl = Request.RequestUri.AbsoluteUri.Replace(Request.RequestUri.AbsolutePath, String.Empty);
            
            if (Request.Content.IsMimeMultipartContent())
            {
                var filename = string.Format(@"{0}_{1}", meta.flowFilename, meta.flowChunkNumber.PadLeft(4, '0'));
                if ("1".Equals(meta.flowTotalChunks))
                {
                    filename = string.Format(@"{0}", meta.flowFilename);
                }
                
                var streamProvider = new CustomMultipartFormDataStreamProvider(PATH, filename);
                var task = Request.Content.ReadAsMultipartAsync(streamProvider).ContinueWith<IEnumerable<FileDesc>>(t =>
                {
                    if (t.IsFaulted || t.IsCanceled)
                    {
                        throw new HttpResponseException(HttpStatusCode.InternalServerError);
                    }

                    if (!"1".Equals(meta.flowTotalChunks) && meta.flowTotalChunks.Equals(meta.flowChunkNumber))
                    {
                        var dest = Path.Combine(PATH, meta.flowFilename);
                        using (var fileS = new FileStream(dest, FileMode.Create))
                        {
                            var files = Directory.EnumerateFiles(PATH)
                                .Where(s => !s.Equals(dest))
                                                 .OrderBy(s => s);
                            foreach (var file in files)
                            {
                                using (var sourceStream = File.OpenRead(file))
                                    sourceStream.CopyTo(fileS);
                            }
                            fileS.Flush();
                            int expectedBytes;
                            if (int.TryParse(meta.flowTotalSize, out expectedBytes))
                            {
                                var info = new FileInfo(dest);
                                if (info.Length == expectedBytes)
                                {
                                    foreach (var file in files)
                                    {
                                        File.Delete(file);
                                    }
                                }
                            }
                        }
                        var fileInfo = streamProvider.FileData.Select(i =>
                        {
                            var uri = dest.Replace(physPath, "~/").Replace(@"\", "/");
                            var info = new FileInfo(dest);
                            return new FileDesc(info.Name, uri, info.Length / 1024);
                        });
                        return fileInfo;
                    }
                    else
                    {
                        var fileInfo = streamProvider.FileData.Select(i =>
                        {
                            var uri = i.LocalFileName.Replace(physPath, "~/").Replace(@"\", "/");
                            var info = new FileInfo(i.LocalFileName);
                            return new FileDesc(info.Name, uri, info.Length / 1024);
                        });
                        return fileInfo;
                    }

                });
                return task;
            }
            else
            {
                throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not formatted correctly or understood"));
            }
        }        
    }
}