remember the code below
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Mining.DataAccess.Data.Repository.IRepository;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.IO;
using Mining.Models.ViewModels;
using Microsoft.AspNetCore.Http.Features;
using Newtonsoft.Json;
using Microsoft.AspNetCore.Http;
using DevExpress.Office.Drawing;
using Mining.Models.Entities.Mines;
using Microsoft.Extensions.Logging;

namespace Mining.App.Areas.Admin.Mines.Pages.SampleAnalyze
{
    public class UpsertModel : PageModel
    {
        private readonly IUnitOfWork _unitOfWork;
        private readonly IWebHostEnvironment _hostingEnvironment;
        private readonly ILogger<UpsertModel> _logger;
        public UpsertModel(IUnitOfWork unitOfWork, IWebHostEnvironment hostingEnvironment, ILogger<UpsertModel> logger)
        {
            _unitOfWork = unitOfWork;
            _hostingEnvironment = hostingEnvironment;
            _logger = logger;
        }

        [BindProperty]
        public SampleAnalyzeVM SampleAnalyzeObj { get; set; }
        public SampleAnalyzeAnalyzeTypeVM SampleAnalyzeAnalyzeTypeObj { get; set; }
        public SampleAnalyzeAnalyzeTypeVM SampleAnalyzeAnalyzeTypeObj2 { get; set; }
        [BindProperty]
        public List<SampleAnalyzeAnalyzeTypeVM> DeniedSampleAnalyzeAnalyzeTypeObjList { get; set; }
        [BindProperty]
        public List<SampleAnalyzeAnalyzeTypeVM> DeniedSampleAnalyzeAnalyzeTypeObjList1 { get; set; }
        [BindProperty]
        public SampleAnalyzeFileVM SampleAnalyzeFileObj { get; set; }
        public SampleAnalyzeFileVM SampleAnalyzeFileObj2 { get; set; }

        public IActionResult OnGet(int? id)
        {
            SampleAnalyzeObj = new SampleAnalyzeVM
            {
                MineOrRangeList = _unitOfWork.MineOrRange.GetMineOrRangeListForDropdown(),
                LaboratoryList = _unitOfWork.Laboratory.GetLaboratoryListForDropdown(),
                SampleTypeList = _unitOfWork.SampleType.GetSampleTypeListForDropdown(),
                SampleStatusList = _unitOfWork.SampleStatus.GetSampleStatusListForDropdown(),
                SampleAnalyze = new Models.Entities.Mines.SampleAnalyze()
            };

            if (id != null)
            {
                SampleAnalyzeObj.SampleAnalyze = _unitOfWork.SampleAnalyze.GetFirstOrDefault(u => u.Id == id);

                if (SampleAnalyzeObj == null)
                {
                    return NotFound();
                }

                // Populate dataList with previous data from the database
                var previousFiles = _unitOfWork.SampleAnalyzeFile.GetAll(u => u.SampleAnalyzeId == id.Value).ToList();
                dataList = previousFiles.Select(file => new DataType
                {
                    File = file.File,
                    FileName = file.FileName,
                    FileExtention = file.FileExtention
                }).ToList();
            }
            return Page();
        }
        [BindProperty]
        public IFormFile UploadfileResult { get; set; }
        [BindProperty]
        public IFormFile UploadfileInvoice { get; set; }
        [BindProperty]
        public IFormFile UploadedFiles { get; set; }

        public class DataType
        {
            public string File { get; set; }
            public string FileName { get; set; }
            public string FileExtention { get; set; }
        }
        public class PostDataFile
        {
            public List<DataType> list { get; set; }
        }

        public static JsonResult jsonResult = new JsonResult("");
        public static List<DataType> dataList = new List<DataType>();
        public static List<DataType> tempDataList = new List<DataType>();
        public static List<DataType> tempDataList2 = new List<DataType>();
        public static bool firstReload = true;


        public IActionResult OnPost()
        {
            if (User.IsInRole(Mining.Utility.SD.MineLab))
            {
                string ContentRootPath = _hostingEnvironment.WebRootPath;

                if (!ModelState.IsValid)
                {
                    //SampleAnalyzeObj.SampleAnalyze = new Models.Entities.Mines.SampleAnalyze();
                    SampleAnalyzeObj = new SampleAnalyzeVM
                    {
                        MineOrRangeList = _unitOfWork.MineOrRange.GetMineOrRangeListForDropdown(),
                        LaboratoryList = _unitOfWork.Laboratory.GetLaboratoryListForDropdown(),
                        SampleTypeList = _unitOfWork.SampleType.GetSampleTypeListForDropdown(),
                        SampleStatusList = _unitOfWork.SampleStatus.GetSampleStatusListForDropdown(),
                        SampleAnalyze = new Models.Entities.Mines.SampleAnalyze()
                    };
                    return Page();
                }
                if (SampleAnalyzeObj.SampleAnalyze.Id == 0)
                {
                    _unitOfWork.SampleAnalyze.Add(SampleAnalyzeObj.SampleAnalyze);
                    _unitOfWork.Save();

                    if (UploadfileResult != null)
                    {
                        var fileResult = Path.Combine(_hostingEnvironment.WebRootPath, @"Files\SamplesAnalyze\", UploadfileResult.FileName);

                        if (System.IO.File.Exists(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id)) == false)
                        {
                            System.IO.Directory.CreateDirectory(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id));
                        }

                        //var fileResult = Path.Combine(_hostingEnvironment.ContentRootPath, @"Files\SamplesAnalyze\", UploadfileResult.FileName);
                        if (fileResult.Length > 0)
                        {
                            string fileName = Guid.NewGuid().ToString();
                            var uploads = Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id);
                            var extention = Path.GetExtension(UploadfileResult.FileName);

                            //using (var fileStream = new FileStream(fileResult, FileMode.Create))
                            using (var fileStream = new FileStream(Path.Combine(uploads, fileName + extention), FileMode.Create))
                            {
                                UploadfileResult.CopyTo(fileStream);
                            }
                            SampleAnalyzeObj.SampleAnalyze.ResultFile = fileName + extention;
                        }
                    }


                    if (UploadfileInvoice != null)
                    {
                        var fileInvoice = Path.Combine(_hostingEnvironment.WebRootPath, @"Files\SamplesAnalyze\", UploadfileInvoice.FileName);

                        if (System.IO.File.Exists(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id)) == false)
                        {
                            System.IO.Directory.CreateDirectory(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id));
                        }

                        //var fileInvoice= Path.Combine(_hostingEnvironment.ContentRootPath, @"Files\SamplesAnalyze\", UploadfileResult.FileName);
                        if (fileInvoice.Length > 0)
                        {
                            string fileName = Guid.NewGuid().ToString();
                            var uploads = Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id);
                            var extention = Path.GetExtension(UploadfileInvoice.FileName);

                            //using (var fileStream = new FileStream(fileResult, FileMode.Create))
                            using (var fileStream = new FileStream(Path.Combine(uploads, fileName + extention), FileMode.Create))
                            {
                                UploadfileInvoice.CopyTo(fileStream);
                            }
                            SampleAnalyzeObj.SampleAnalyze.InvoiceFile = fileName + extention;
                        }
                    }

                    _unitOfWork.SampleAnalyze.Update(SampleAnalyzeObj.SampleAnalyze);
                    _unitOfWork.Save();

                    int SampleAnalyzeId = SampleAnalyzeObj.SampleAnalyze.Id;
                    PrepareSampleAnalyzeAnalyzeType(SampleAnalyzeId);

                    //tempDataList.Clear();
                    PrepareSampleAnalyzeFile(SampleAnalyzeId);
                }
                else
                {
                    var objFromDb = _unitOfWork.SampleAnalyze.Get(SampleAnalyzeObj.SampleAnalyze.Id);
                    if (UploadfileResult != null)
                    {
                        var fileResult = Path.Combine(_hostingEnvironment.WebRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id, UploadfileResult.FileName);

                        if (System.IO.File.Exists(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id)) == false)
                        {
                            System.IO.Directory.CreateDirectory(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id));
                        }

                        if (fileResult.Length > 0)
                        {
                            string fileName = Guid.NewGuid().ToString();
                            var uploads = Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id);
                            var extention = Path.GetExtension(UploadfileResult.FileName);
                            if (objFromDb.ResultFile != null)
                            {
                                if (System.IO.File.Exists(Path.Combine(uploads, objFromDb.ResultFile.TrimStart('\\'))))
                                {
                                    System.IO.File.Delete(Path.Combine(uploads, objFromDb.ResultFile.TrimStart('\\')));
                                }
                            }
                            using (var fileStream = new FileStream(Path.Combine(uploads, fileName + extention), FileMode.Create))
                            {
                                UploadfileResult.CopyTo(fileStream);
                            }
                            SampleAnalyzeObj.SampleAnalyze.ResultFile = fileName + extention;
                        }
                    }
                    else
                    {
                        SampleAnalyzeObj.SampleAnalyze.ResultFile = objFromDb.ResultFile;
                    }

                    if (UploadfileInvoice != null)
                    {
                        var fileInvoice = Path.Combine(_hostingEnvironment.WebRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id, UploadfileInvoice.FileName);

                        if (System.IO.File.Exists(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id)) == false)
                        {
                            System.IO.Directory.CreateDirectory(Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id));
                        }

                        if (fileInvoice.Length > 0)
                        {
                            string fileName = Guid.NewGuid().ToString();
                            var uploads = Path.Combine(ContentRootPath, @"Files\SamplesAnalyze\" + SampleAnalyzeObj.SampleAnalyze.Id);
                            var extention = Path.GetExtension(UploadfileInvoice.FileName);
                            if (objFromDb.InvoiceFile != null)
                            {
                                if (System.IO.File.Exists(Path.Combine(uploads, objFromDb.InvoiceFile.TrimStart('\\'))))
                                {
                                    System.IO.File.Delete(Path.Combine(uploads, objFromDb.InvoiceFile.TrimStart('\\')));
                                }
                            }
                            using (var fileStream = new FileStream(Path.Combine(uploads, fileName + extention), FileMode.Create))
                            {
                                UploadfileInvoice.CopyTo(fileStream);
                            }
                            SampleAnalyzeObj.SampleAnalyze.InvoiceFile = fileName + extention;
                        }
                    }
                    else
                    {
                        SampleAnalyzeObj.SampleAnalyze.InvoiceFile = objFromDb.InvoiceFile;
                    }
                    _unitOfWork.SampleAnalyze.Update(SampleAnalyzeObj.SampleAnalyze);
                    _unitOfWork.Save();

                    int SampleAnalyzeId = SampleAnalyzeObj.SampleAnalyze.Id;
                    PrepareSampleAnalyzeAnalyzeType(SampleAnalyzeId);
                    //tempDataList.Clear();
                    PrepareSampleAnalyzeFile(SampleAnalyzeId);
                }
                //_unitOfWork.Save();
                return RedirectToPage("./index");
            }
            else
            {
                SampleAnalyzeObj = new SampleAnalyzeVM
                {
                    MineOrRangeList = _unitOfWork.MineOrRange.GetMineOrRangeListForDropdown(),
                    LaboratoryList = _unitOfWork.Laboratory.GetLaboratoryListForDropdown(),
                    SampleTypeList = _unitOfWork.SampleType.GetSampleTypeListForDropdown(),
                    SampleStatusList = _unitOfWork.SampleStatus.GetSampleStatusListForDropdown(),
                    SampleAnalyze = new Models.Entities.Mines.SampleAnalyze()
                };

                return Page();
            }
        }

        public void PrepareSampleAnalyzeAnalyzeType(int sampleAnalyzeId)
        {
            List<SampleAnalyzeAnalyzeTypeVM> SampleAnalyzeAnalyzeTypeObjList = new List<SampleAnalyzeAnalyzeTypeVM>();
            DeniedSampleAnalyzeAnalyzeTypeObjList = new List<SampleAnalyzeAnalyzeTypeVM>();


            for (int i = 0; i < lstString.Count; i++)
            {
                SampleAnalyzeAnalyzeTypeObj2 = new SampleAnalyzeAnalyzeTypeVM
                {
                    SampleAnalyzeAnalyzeType = new Models.Entities.Mines.SampleAnalyzeAnalyzeType()
                };

                SampleAnalyzeAnalyzeTypeObj2.SampleAnalyzeAnalyzeType.SampleAnalyzeId = sampleAnalyzeId;
                SampleAnalyzeAnalyzeTypeObj2.SampleAnalyzeAnalyzeType.AnalyzeTypeId = int.Parse(lstString[i]);
                //EventTeacherObj2.EventTeacher.Id = null;
                SampleAnalyzeAnalyzeTypeObjList.Add(SampleAnalyzeAnalyzeTypeObj2);
            }

            var objFromDb = _unitOfWork.SampleAnalyzeAnalyzeType.GetAll(u => u.SampleAnalyzeId == sampleAnalyzeId, null, null).ToList();
            if (objFromDb == null)
            {
                return;
            }
            foreach (var item in objFromDb)
            {
                _unitOfWork.SampleAnalyzeAnalyzeType.Remove(item);
            }

            if (SampleAnalyzeAnalyzeTypeObjList.Count > 0)
            {
                _unitOfWork.SampleAnalyzeAnalyzeType.AddRange(SampleAnalyzeAnalyzeTypeObjList);
            }

            _unitOfWork.Save();
        }
        public class PostData
        {
            public string[] list { get; set; }
        }


        public static List<string> lstString = new List<string>();

        public IActionResult OnPostSend()
        {
            List<string> sPostValue1 = new List<string>();
            {
                var syncIOFeature = HttpContext.Features.Get<IHttpBodyControlFeature>();
                if (syncIOFeature != null)
                {
                    syncIOFeature.AllowSynchronousIO = true;
                }
                MemoryStream stream = new MemoryStream();
                Request.Body.CopyTo(stream);
                stream.Position = 0;
                using (StreamReader reader = new StreamReader(stream))
                {
                    string requestBody = reader.ReadToEnd();
                    if (requestBody.Length > 0)
                    {
                        var obj = JsonConvert.DeserializeObject<PostData>(requestBody);
                        if (obj != null)
                        {
                            for (int i = 0; i < obj.list.Length; i++)
                            {
                                sPostValue1.Add(obj.list[i]);
                            }
                        }
                    }
                }
            }

            lstString = sPostValue1;

            return new JsonResult(lstString);
        }

        public IActionResult OnPostDelete()
        {
            // Clear the tempDataList to ensure it only holds the current session data
            tempDataList.Clear();

            string contentRootPath = _hostingEnvironment.WebRootPath;
            bool isFileDeleted = false;

            // Step 1: Retrieve DataList JSON from the request
            string dataListJson = Request.Form["DataList"];
            if (string.IsNullOrEmpty(dataListJson))
            {
                _logger.LogWarning("DataList is empty or missing.");
                return new JsonResult(new { success = false, message = "DataList is empty or missing." });
            }

            _logger.LogInformation($"Received DataList JSON: {dataListJson}");

            // Step 2: Deserialize the DataList JSON
            PostDataFile obj;
            try
            {
                obj = JsonConvert.DeserializeObject<PostDataFile>(dataListJson);
                _logger.LogInformation("DataList deserialized successfully.");
            }
            catch (JsonException ex)
            {
                _logger.LogError($"Deserialization failed: {ex.Message}");
                return new JsonResult(new { success = false, message = "Failed to deserialize DataList.", error = ex.Message });
            }

            if (obj?.list != null && obj.list.Count > 0)
            {
                // Create a HashSet of the incoming files for faster lookup
                var incomingFiles = new HashSet<string>(obj.list.Select(d => d.File));

                // Step 3: Remove items from dataList that are not in the incoming data, and delete associated files
                var itemsToRetain = new List<DataType>();

                foreach (var item in dataList)
                {
                    if (incomingFiles.Contains(item.File))
                    {
                        itemsToRetain.Add(item);  // Retain items present in incoming data
                    }
                    else
                    {
                        // Delete the associated file if it exists
                        string fileToDelete = Path.Combine(contentRootPath, @"Files\TempSamplesAnalyze\", item.File);
                        if (System.IO.File.Exists(fileToDelete))
                        {
                            try
                            {
                                System.IO.File.Delete(fileToDelete);
                                isFileDeleted = true;
                                _logger.LogInformation($"File {item.File} deleted successfully.");
                            }
                            catch (Exception ex)
                            {
                                _logger.LogError($"Error deleting file {item.File}: {ex.Message}");
                            }
                        }
                    }
                }

                // Update dataList to retain only the intersected items
                dataList = itemsToRetain;
                _logger.LogInformation("DataList updated successfully to retain only incoming items.");
            }
            else
            {
                _logger.LogWarning("Deserialized DataList is null or empty.");
                return new JsonResult(new { success = false, message = "No valid items found in DataList." });
            }

            // Synchronize tempDataList with the updated dataList
            tempDataList = dataList;

            // Step 4: Return the Final DataList as JSON with file deletion status
            string finalJsonString = JsonConvert.SerializeObject(dataList.ToList());
            _logger.LogInformation($"Final DataList JSON: {finalJsonString}");

            return new JsonResult(new { success = true, dataList = finalJsonString, fileDeleted = isFileDeleted });
        }


        public IActionResult OnPostFileSend()
        {
            // Clear dataList at the start to ensure it holds only current session data
            //dataList.Clear();
            //dataList = dataList.Intersect(tempDataList, new DataTypeComparer()).ToList();
            tempDataList.Clear();  // Clear tempDataList as well if necessary

            string contentRootPath = _hostingEnvironment.WebRootPath;

            // Step 1: Handle UploadedFiles
            var uploadedFile = Request.Form.Files["UploadedFiles"];
            if (uploadedFile != null && uploadedFile.Length > 0)
            {
                string tempDirectory = Path.Combine(contentRootPath, @"Files\TempSamplesAnalyze\");
                if (!Directory.Exists(tempDirectory))
                    Directory.CreateDirectory(tempDirectory);

                string fileName = Path.GetFileNameWithoutExtension(uploadedFile.FileName);
                string extension = Path.GetExtension(uploadedFile.FileName);
                string filePath = Path.Combine(tempDirectory, fileName + extension);

                try
                {
                    using (var fileStream = new FileStream(filePath, FileMode.Create))
                    {
                        uploadedFile.CopyTo(fileStream);
                    }
                    _logger.LogInformation($"File saved successfully at {filePath}");
                }
                catch (Exception ex)
                {
                    _logger.LogError($"Error saving file: {ex.Message}");
                    return new JsonResult(new { success = false, message = "Failed to save the uploaded file.", error = ex.Message });
                }
            }
            else
            {
                _logger.LogWarning("No file was uploaded.");
                return new JsonResult(new { success = false, message = "No file was uploaded." });
            }

            // Step 2: Handle DataList
            string dataListJson = Request.Form["DataList"];
            if (string.IsNullOrEmpty(dataListJson))
            {
                _logger.LogWarning("DataList is empty or missing.");
                return new JsonResult(new { success = false, message = "DataList is empty or missing." });
            }

            _logger.LogInformation($"Received DataList JSON: {dataListJson}");

            // Step 3: Deserialize the DataList JSON
            PostDataFile obj;
            try
            {
                obj = JsonConvert.DeserializeObject<PostDataFile>(dataListJson);
                _logger.LogInformation("DataList deserialized successfully.");
            }
            catch (JsonException ex)
            {
                _logger.LogError($"Deserialization failed: {ex.Message}");
                return new JsonResult(new { success = false, message = "Failed to deserialize DataList.", error = ex.Message });
            }

            // Step 4: Validate and Process the Deserialized Data
            if (obj?.list != null && obj.list.Count > 0)
            {
                foreach (var item in obj.list)
                {
                    if (!dataList.Exists(d => d.File == item.File))
                    {
                        dataList.Add(item);  // Only add unique items to avoid duplicates
                    }
                    else
                    {
                        _logger.LogInformation($"Duplicate entry found for file: {item.File}");
                    }
                }

                _logger.LogInformation("DataList processed successfully.");
            }
            else
            {
                _logger.LogWarning("Deserialized DataList is null or empty.");
                return new JsonResult(new { success = false, message = "No valid items found in DataList." });
            }

            tempDataList=dataList; // Clear tempDataList after use

            // Step 6: Return the Final DataList as JSON
            string finalJsonString = JsonConvert.SerializeObject(dataList.ToList());
            _logger.LogInformation($"Final DataList JSON: {finalJsonString}");
            jsonResult = new JsonResult(finalJsonString);
            return jsonResult;

        }
        
        
        
        
        public class DataTypeComparer : IEqualityComparer<DataType>
        {
            public bool Equals(DataType x, DataType y)
            {
                return x.File == y.File;
            }

            public int GetHashCode(DataType obj)
            {
                return obj.File.GetHashCode();
            }
        }

        public void PrepareSampleAnalyzeFile(int sampleAnalyzeId)
        {
            List<SampleAnalyzeFileVM> SampleAnalyzeFileObjList = new List<SampleAnalyzeFileVM>();
            //dataList;
            //dataList = dataList.Intersect(tempDataList, new DataTypeComparer()).ToList();
            //dataList.S

            for (int i = 0; i < dataList.Count; i++)
            {
                SampleAnalyzeFileObj2 = new SampleAnalyzeFileVM
                {
                    SampleAnalyzeFile = new Models.Entities.Mines.SampleAnalyzeFile()
                };

                SampleAnalyzeFileObj2.SampleAnalyzeFile.SampleAnalyzeId = sampleAnalyzeId;
                SampleAnalyzeFileObj2.SampleAnalyzeFile.File = dataList[i].File;
                SampleAnalyzeFileObj2.SampleAnalyzeFile.FileName = dataList[i].FileName;
                SampleAnalyzeFileObj2.SampleAnalyzeFile.FileExtention = dataList[i].FileExtention;
                SampleAnalyzeFileObjList.Add(SampleAnalyzeFileObj2);
            }
            if (SampleAnalyzeFileObjList.Count >= 0)
            {
                var objFromDb = _unitOfWork.SampleAnalyzeFile.GetAll(u => u.SampleAnalyzeId == sampleAnalyzeId, null, null).ToList();
                if (objFromDb == null)
                {
                    return;
                }
                foreach (var item in objFromDb)
                {
                    _unitOfWork.SampleAnalyzeFile.Remove(item);
                }

                _unitOfWork.SampleAnalyzeFile.AddRange(SampleAnalyzeFileObjList);
                _unitOfWork.Save();
            }
        }
    }
}