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 _logger;
public UpsertModel(IUnitOfWork unitOfWork, IWebHostEnvironment hostingEnvironment, ILogger 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();
        }
    }
}

}