ASP.NET Uploading and Downloading files

gistfile1.cs

// Sample model uses HttpPostedFileBase to pass the file to the controller
public class CustomerStatementModel
{
    public int Id { get; set; }
    public string Description { get; set; }
    public HttpPostedFileBase CustomerStatementFile { get; set; }
}

// POST:/Customer/Statement
// To upload a customer statment post to this action
[HttpPost]
public async Task<ActionResult> Statement(CustomerStatementModel model)
{
    if (model.CustomerStatementFile.ContentType != "excel" || !model.CustomerStatementFile.FileName.EndsWith("xls"))
    {
        ModelState.AddModelError("CustomerStatementFile", "Must be excel");
        return View();
    }
    var filePath = Path.Combine(FileServerPath, Path.GetFileName(model.CustomerStatementFile.FileName));
    using (FileStream stream = System.IO.File.Create(filePath))
    {
        model.CustomerStatementFile.InputStream.Seek(0, SeekOrigin.Begin);
        await model.CustomerStatementFile.InputStream.CopyToAsync(stream);
        stream.Close();
    }
    return Redirect("Index");
}

// GET /Customer/Statement/2
[HttpGet]
public ActionResult Statement(int id)
{
    var customerFile = repository.GetCustomerStatementFile(id);

    if (customerFile == null)
    {
        return HttpNotFound();
    }

    var filePath = Path.Combine(FileServerPath, customerFile.FileName);

    if (!System.IO.File.Exists(filePath))
    {
        return HttpNotFound();
    }

    var mimeType = filePath.EndsWith(".xlsx") ? "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" : "application/vnd.ms-excel";

    return File(filePath, mimeType, Path.GetFileName(filePath));
}