@(Html.Kendo().Grid(Model)
      .Name("gridLetters")
      .Columns(columns =>
      {
	      columns.Bound(p => p.Id).ClientTemplate("<a href='" + Url.Action("View", "Letter", new { letterId = "#:Id#" }) + "'>#=Id#</i></a>");
	      columns.Bound(p => p.Subject);
	      columns.Bound(p => p.CompanyName).Title("Company");
	      columns.Bound(p => p.BrandName).Title("Brand");
	      columns.Bound(p => p.Location.Name).Title("Location");
	      columns.Bound(p => p.LetterType.Name).Title("RL Type");	      
      })
      .ToolBar(toolbar =>
      {
	      toolbar.Search();
      })
      .Sortable()
      .Navigatable()
      .Resizable(r => r.Columns(true))
      .Pageable(pageable => pageable
	                .Refresh(true)
	                .PageSizes(true)
	                .ButtonCount(5))
      .Filterable()
      .Scrollable()
      .ClientDetailTemplateId("detailTemplate")
      .HtmlAttributes(new { style = "height:430px;" })
      .DataSource(dataSource => dataSource
	                  .Ajax()
	                  .Sort(x => x.Add("Id").Descending())
	                  .PageSize(20)
	                  .ServerOperation(false)
	  ))

@section Scripts {
	<script id="detailTemplate" type="text/kendo-tmpl">
	    @(Html.Kendo().TabStrip()
	          .Name("tabStrip_#=Id#")
	          .SelectedIndex(0)
	          .Animation(animation => animation.Open(open => open.Fade(FadeDirection.In)))
	          .Items(items =>
	          {
		          items.Add().Text("History").Content(@<text>@Html.DisplayFor(m => m.History, "LetterHistory")</text>);
		          items.Add().Text("Details").Content("");
	          }).ToClientTemplate())
	</script>
}

@model IList<BusApp.Domain.Models.BusinessObjects.LetterActionHistoryFlatModel>

@(Html.Kendo().Grid(Model)
      .Name("gridLetterHistory")
      .Columns(columns =>
      {
	      columns.Bound(p => p.ActionStamp).Title("Stamp").Format("{0:dd-MMM-yyyy}");
	      columns.Bound(p => p.LetterActionName).Title("Action");
	      columns.Bound(p => p.ActionTakenByName).Title("Taken By");
      })
      .Navigatable()
      .Resizable(r=>r.Columns(true))
      .Pageable(pageable => pageable
	                .Refresh(true)
	                .PageSizes(true)
	                .ButtonCount(10))
      .Filterable()
      .Scrollable()
      .DataSource(dataSource => dataSource
	                  .Ajax()
	                  .Sort(x => x.Add("ActionStamp").Descending())
	                  .PageSize(20)
	                  .ServerOperation(false)
	  )
	)

.DataSource(ds =>
        {
            ds.Read(read => read.Action(Model.ActionMethod, Model.ControllerActionMethod).Type(HttpVerbs.Post));
            if (Model.SeriesGrouped)
            {
                //to create data groups
                ds.Group(group => group.Add(model => model.Group)).Sort(s => s.Add(m => m.Order));
            }
        })

public class MyModelClass
    {
        public string Group { get; set; }
        public string Category { get; set; }
        public DateTime Order { get; set; } 
      
    }

{Group:"A", Order:"01/2021", value="1000"}
{Group:"A", Order:"02/2021", value="1200"}
{Group:"A", Order:"03/2021", value="1100"}
{Group:"B", Order:"01/2021", value="2000"}
{Group:"B", Order:"02/2021", value="2200"}
{Group:"B", Order:"03/2021", value="2100"}

{Group:"A", Order:"02/2021", value="1200"}
{Group:"A", Order:"03/2021", value="1100"}
{Group:"B", Order:"01/2021", value="2000"}
{Group:"B", Order:"02/2021", value="2200"}
{Group:"B", Order:"03/2021", value="2100"}

using Csla;
using Finbuckle.MultiTenant;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.StaticFiles;
using Newtonsoft.Json;
using Portal.Library;
using System.Net;
using System.Net.Http.Headers;
using System.Security.Claims;
using System.Text;

namespace WebUI.Controllers
{
    public class FileStore : Csla.Web.Mvc.Controller
    {
        private string UploadBasePath = "wwwroot\\uploads";
        private string UploadStoragePath = "wwwroot\\storage";

        public WebUI.TenantInfo? TenantInfo { get; private set; }

        public FileStore(IMultiTenantContextAccessor<WebUI.TenantInfo> mtaccessor)
        {
            TenantInfo = mtaccessor.MultiTenantContext.TenantInfo;
        }

        public class ChunkMetaData
        {
            public string UploadUid { get; set; }
            public string FileName { get; set; }
            public string RelativePath { get; set; }
            public string ContentType { get; set; }
            public long ChunkIndex { get; set; }
            public long TotalChunks { get; set; }
            public long TotalFileSize { get; set; }
        }

        public class FileResult
        {
            // Because the chunks are sent in a specific order,
            // the server is expected to send back a response
            // with the meta data of the chunk that is uploaded.
            public bool uploaded { get; set; }

            public string fileUid { get; set; }

            public string fileStorageGuid { get; set; } // internal GUID in DB per file not per session

            public string selector { get; set; } // because the UID isn't used or sent for the fallback Save()
        }

        public void AppendToFile(string fullPath, IFormFile content)
        {
            try
            {
                using (FileStream stream = new(fullPath, FileMode.Append, FileAccess.Write, FileShare.ReadWrite))
                {
                    content.CopyTo(stream);
                }
            }
            catch (IOException ex)
            {
                throw ex;
            }
        }

        public ActionResult ChunkSave(IEnumerable<IFormFile> files, string metaData)
        {
            if (metaData == null)
            {
                return Save(files);
            }

            MemoryStream ms = new(Encoding.UTF8.GetBytes(metaData));

            JsonSerializer serializer = new();
            ChunkMetaData chunkData;
            using (StreamReader streamReader = new(ms))
            {
                chunkData = (ChunkMetaData)serializer.Deserialize(streamReader, typeof(ChunkMetaData));
            }

            string path = Path.Combine(UploadBasePath, chunkData.FileName);
            // The Name of the Upload component is "files".
            if (files != null)
            {
                foreach (var file in files)
                {
                    AppendToFile(path, file);
                }
            }

            var isUploaded = chunkData.TotalChunks - 1 <= chunkData.ChunkIndex;
            FileResult fileBlob = new()
            {
                uploaded = isUploaded,
                fileUid = chunkData.UploadUid
            };

            if (isUploaded)
            {
                var bytes = Encoding.UTF8.GetBytes(chunkData.FileName);

                fileBlob.fileStorageGuid = CatalogAndMoveFileAsync(chunkData.FileName, path).ToString();
                fileBlob.selector = Convert.ToBase64String(bytes);
            }

            return Json(fileBlob);
        }

        private Guid CatalogAndMoveFileAsync(string FileName, string FilePath)
        {
            //sanity
            if (System.IO.File.Exists(FilePath))
            {
                // step 1 - generate guid in files table by inserting the requisite information
                var _user = Csla.ApplicationContext.User as ClaimsPrincipal;
                int userID = int.Parse(_user.Claims.FirstOrDefault(S => S.Type == "UserID").Value.ToString());

                var finfo = new FileInfo(FilePath);

                var obj = DataPortal.Create<FileStorage>();
                obj.UserID = userID;
                obj.Extension = Path.GetExtension(FileName);
                obj.OrigName = FileName;
                obj.KBSize = finfo.Length / 1024;
                obj.SiteID = TenantInfo.SiteID;

                // TODO: revisit and see if SaveObjectAsync updates our object v6
                // use the object's own save function to update the object
                obj = obj.Save();

                // do we have to re-fetch or is the object guid updated automatically?
                if (obj.ID != Guid.Empty)
                {
                    // step 2 - determine new name, location, move to it
                    string StorageSubfolders = Path.Combine(UploadStoragePath, obj.RelPath);

                    try
                    {
                        System.IO.Directory.CreateDirectory(StorageSubfolders); // so glad this func does it in one go

                        var newFilePath = Path.Combine(StorageSubfolders, obj.InternalName);
                        System.IO.File.Move(FilePath, newFilePath);

                        if (System.IO.File.Exists(newFilePath))
                        {
                            // step 3 - return the guid
                            return obj.ID;
                        }
                    }
                    catch (Exception ex)
                    {
                        if (obj.ID != Guid.Empty)
                        {
                            DataPortal.Delete<FileStorage>(obj.ID, userID);
                        }

                        throw new FileNotFoundException("FileStorage moving file", ex);
                    }
                }
            }

            return Guid.Empty;
        }

        public ActionResult RemoveAsync(string[] fileNames, string[] FileStorageUIDs)
        {
            // we don't actually care about fileNames, telerik always sends *something* related to that though
            // we rely on our file UID(s) that were sent back and hopefully captured in the onSuccess event

            // The parameter of the Remove action must be called "fileNames"
            if (FileStorageUIDs.Length > 0)
            {
                foreach (var fUID in FileStorageUIDs)
                {
                    // get the current UID to be 100% sure we're deleting only our own file
                    var _user = Csla.ApplicationContext.User as ClaimsPrincipal;
                    int userID = int.Parse(_user.Claims.FirstOrDefault(S => S.Type == "UserID").Value.ToString());

                    var obj = DataPortal.Fetch<FileStorage>(new Guid(fUID), userID);

                    if (obj.ID != Guid.Empty)
                    {
                        var basePath = Path.Combine(UploadStoragePath, obj.RelPath);
                        var physicalPath = Path.Combine(basePath, obj.InternalName);
                        if (System.IO.File.Exists(physicalPath))
                        {
                            System.IO.File.Delete(physicalPath);

                           //TODO: maybe try/catch?
                            if (Directory.EnumerateFiles(basePath).Any() == false)
                            {
                                Directory.Delete(basePath, true);
                            }

                            // we already fetched with UID
                            DataPortal.Delete<FileStorage>(obj.ID, userID);
                        }
                    }
                }
            }

            // Return an empty string to signify success
            return Content("");
        }

        // TODO: while this method fully works, for whatever reason it corrupts files when we fall back to it
        public ActionResult Save(IEnumerable<IFormFile> files)
        {
            List<string> fileNames = new();
            List<FileResult> results = new();
            
            // The Name of the Upload component is "files".
            if (files != null)
            {
                foreach (var file in files)
                {
                    var fileContent = ContentDispositionHeaderValue.Parse(file.ContentDisposition);

                    // Some browsers send file names with full path.
                    // The demo is interested only in the file name.
                    var fileName = Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
                    var physicalPath = Path.Combine(UploadBasePath, fileName);

                    using var fileStream = new FileStream(physicalPath, FileMode.Create);
                    file.CopyToAsync(fileStream);

                    fileNames.Add(fileName);
                }

                // since we can't delete while in the scope of the loop there, we have to do a second one
                foreach (var fileName in fileNames)
                {
                    var physicalPath = Path.Combine(UploadBasePath, fileName);

                    var fileStorageGuid = CatalogAndMoveFileAsync(fileName, physicalPath);
                    string guidString = fileStorageGuid.ToString();

                    var bytes = Encoding.UTF8.GetBytes(fileName);

                    results.Add(new FileResult()
                    {
                        uploaded = true,
                        fileStorageGuid = guidString,
                        selector = Convert.ToBase64String(bytes)
                    });
                }

                return Json(results);
            }

            return Content("");
        }

        public async Task GetFile(string FileStorageUID)
        {
            var _user = Csla.ApplicationContext.User as ClaimsPrincipal;
            int userID = int.Parse(_user.Claims.FirstOrDefault(S => S.Type == "UserID").Value.ToString());

            // TODO: maybe add a func to the user dal to fetch hierarchy?
            // TODO: check role here, if UID doesn't match, don't pass userID

            var obj = await DataPortal.FetchAsync<FileStorage>(new Guid(FileStorageUID), 0); // uid is second param if needed

            if (obj.ID != Guid.Empty)
            {
                var basePath = Path.Combine(UploadStoragePath, obj.RelPath);
                var physicalPath = Path.Combine(basePath, obj.InternalName);
                if (System.IO.File.Exists(physicalPath))
                {
                    var provider = new FileExtensionContentTypeProvider();
                    if (!provider.TryGetContentType(physicalPath, out string contentType))
                    {
                        contentType = "application/octet-stream";
                    }

                    Response.Clear();
                    Response.Headers.Add("Content-Disposition", "inline;filename=" + obj.OrigName);
                    Response.ContentType = contentType;

                    await Response.SendFileAsync(physicalPath);
                }
            }
        }
    }
}

                        @(Html.Kendo().Upload()
                            .Name("files")
                            .Async(a => a
                                .Save("ChunkSave", "FileStore")
                                .Remove("Remove", "FileStore")
                                .AutoUpload(true)
                                .ChunkSize(10240) 
                            )
                            .Validation(validation => validation
                                //.AllowedExtensions(new string[] { ".gif", ".jpg", ".png" })
                                .MaxFileSize(200000000) // 200 megs
                               //.MinFileSize(512)
                            )
                            .Events(events => events
                                .Success("onSuccess")
                                .Remove("onRemove")
                                .Upload("onUpload")
                            ).Multiple(false) // one file and one file only
                        ) 

	<div class="row mt-3">
		<div class="col-lg-4">
			@(Html.Kendo().DropDownListFor(m => m.CategoryHeadId)
			      .Size(ComponentSize.Medium)
				  .Rounded(Rounded.Medium)
				  .FillMode(FillMode.Solid)
				  .OptionLabel("Select head category...")
				  .HtmlAttributes(new { style = "width: 100%" })
				  .DataTextField("Name")
				  .DataValueField("Id")
				  .DataSource(source =>
				  {
					  source.Read(read =>
					  {
						  read.Action("GetLookupCategoriesHead", "Api");
					  });
				  })
				)
		</div>
		<div class="col-lg-4">
			@(Html.Kendo().DropDownListFor(m => m.CategoryMainId)
			      .Size(ComponentSize.Medium)
				.Rounded(Rounded.Medium)
				.FillMode(FillMode.Solid)
				.OptionLabel("Select main category...")
				.HtmlAttributes(new { style = "width: 100%" })
				.DataTextField("Name")
				.DataValueField("Id")
				.DataSource(source =>
				{
					source.Read(read =>
					{
						read.Action("GetLookupCategoriesMain", "Api")
						    .Data("filterMainCategories");
					})
					.ServerFiltering(true);
				})
				.Enable(false)
				.AutoBind(false)
				.CascadeFrom("CategoryHeadId")
				)
		</div>
		<div class="col-lg-4">
			@(Html.Kendo().DropDownListFor(m => m.CategorySubId)
				.Size(ComponentSize.Medium)
				.Rounded(Rounded.Medium)
				.FillMode(FillMode.Solid)
				.OptionLabel("Select sub-category...")
				.HtmlAttributes(new { style = "width: 100%" })
				.DataTextField("Name")
				.DataValueField("Id")
				.DataSource(source =>
				{
					source.Read(read =>
					{
						read.Action("GetLookupCategoriesSub", "Api")
						    .Data("filterSubCategories");
					})
					.ServerFiltering(true);
				})
				.Enable(false)
				.AutoBind(false)
				.CascadeFrom("CategoryMainId")
				)
		</div>
	</div>

@section Scripts {
	<script>
		function filterMainCategories() {
			return {
				headId: $("#CategoryHeadId").val()
			};
		}

		function filterSubCategories() {
			return {
				headId: $("#CategoryHeadId").val(),
				mainId: $("#CategoryMainId").val()
			};
		}
	</script>
}

    public async Task<JsonResult> GetLookupCategoriesHead()
    {
        var result = await serviceLookUps.GetAllCategoriesHeadAsync();
        return new JsonResult(result);
    }

    public async Task<JsonResult> GetLookupCategoriesMain(int headId)
    {
        var result = await serviceLookUps.GetAllCategoriesMainAsync(headId);
        return new JsonResult(result);
    }

    public async Task<JsonResult> GetLookupCategoriesSub(int headId, int mainId)
    {
        var result = await serviceLookUps.GetAllCategoriesSubAsync(headId, mainId);
        return new JsonResult(result);
    }

[DebuggerDisplay($"{nameof(Id)}: {{{nameof(Id)},nq}}, {nameof(Name)}: {{{nameof(Name)}}}, {nameof(Active)}: {{{nameof(Active)}}}")]
public class LookupCategoryHeadModel
{
    public int    Id     { get; set; }
    public string Name   { get; set; } = string.Empty;
    public bool   Active { get; set; }
}

[DebuggerDisplay($"{nameof(Id)}: {{{nameof(Id)},nq}}, {nameof(Name)}: {{{nameof(Name)}}}, {nameof(Active)}: {{{nameof(Active)}}}")]
public class LookupCategoryMainModel
{
    public int    Id     { get; set; }
    public int    HeadId { get; set; }
    public string Name   { get; set; } = string.Empty;
    public bool   Active { get; set; }
}

[DebuggerDisplay($"{nameof(Id)}: {{{nameof(Id)},nq}}, {nameof(Name)}: {{{nameof(Name)}}}, {nameof(Active)}: {{{nameof(Active)}}}")]
public class LookupCategorySubModel
{
    public int    Id     { get; set; }
    public int    HeadId { get; set; }
    public int    MainId { get; set; }
    public string Name   { get; set; } = string.Empty;
    public bool   Active { get; set; }
}

@page
@model IndexModel

@inject Microsoft.AspNetCore.Antiforgery.IAntiforgery Xsrf
@Html.AntiForgeryToken()
@{
    ViewData["Title"] = "Home page";
}
--------------------------------------------------------------------------------
 
 
<div class="text-center">
    <h1 class="display-4">Welcome</h1>


         @(Html.Kendo().DropDownList()
            .Name("MyDropdownn")
            .DataTextField("Text")
            .DataValueField("Value")
            .HtmlAttributes(new { style = "width:300px;" })
            .AutoBind(false)
            .Filter(FilterType.Contains)      
            .DataSource(ds => ds
                .Custom()
                .Transport(transport => transport
                    .Read(r => r
                        .Url("/Index?handler=Sports")
                    ))
                    .ServerFiltering(false)
                )
            )

</div>

Index.cshtml.cs

        public JsonResult OnGetSports()
        {
            var allSports1 = db.Sports.Where(x => x.SportID > 0).Select(x => new DropDownModel
            {
                Text = x.Name,
                Value = x.SportID 
            }).ToList();

            return new JsonResult(allSports1);
        }

    public class DropDownModel
    {
        public int Value { get; set; }
        public string Text { get; set; } = String.Empty;
    }