using System;
using System.IO;
using DevExpress.Xpo;
using DevExpress.ExpressApp;
using System.ComponentModel;
using DevExpress.Persistent.Base;
using DevExpress.ExpressApp.Utils;
using DevExpress.Persistent.BaseImpl;
using DevExpress.Persistent.Validation;
using System.Linq;

namespace FileSystemData.BusinessObjects {
    /// <summary>
    /// This class enables you to store uploaded files in a centralized file system location instead of the database. You can configure the file system store location via the static FileSystemDataModule.FileSystemStoreLocation property.
    /// </summary>
    [DefaultProperty(nameof(FileName))]
    public class FileSystemStoreObject : BaseObject, IFileData, IEmptyCheckable {
        private Stream tempSourceStream;
        private string tempFileName = string.Empty;
        private static object syncRoot = new object();
        public FileSystemStoreObject(Session session) : base(session) { }
        public string RealFileName {
            get {
                if (!string.IsNullOrEmpty(FileName) && Oid != Guid.Empty)
                    return Path.Combine(FileSystemDataModule.FileSystemStoreLocation, string.Format("{0}-{1}", Oid, FileName));
                return null;
            }
        }
        protected virtual void SaveFileToStore() {
            if(!string.IsNullOrEmpty(RealFileName) && TempSourceStream != null)  {
                try {
                    using(Stream destination = File.Create(RealFileName)) { //T582918
                        FileSystemDataModule.CopyStream(TempSourceStream, destination);
                        Size = (int)destination.Length;
                    }
                }
                catch(DirectoryNotFoundException exc) {
                    throw new UserFriendlyException(exc);
                }
            }
        }
        private void RemoveOldFileFromStore() {
            //Dennis: We need to remove the old file from the store when saving the current object.
            if (!string.IsNullOrEmpty(tempFileName) && tempFileName != RealFileName) {//B222892
                try {
                    File.Delete(tempFileName);
                    tempFileName = string.Empty;
                } catch (DirectoryNotFoundException exc) {
                    throw new UserFriendlyException(exc);
                }
            }
        }
        protected override void OnSaving() {
            base.OnSaving();
            Guard.ArgumentNotNullOrEmpty(FileSystemDataModule.FileSystemStoreLocation, "FileSystemStoreLocation");
            lock (syncRoot) {
                if (!Directory.Exists(FileSystemDataModule.FileSystemStoreLocation))
                    Directory.CreateDirectory(FileSystemDataModule.FileSystemStoreLocation);
            }
            SaveFileToStore();
            RemoveOldFileFromStore();
        }
        protected override void OnDeleting() {
            //Dennis: We need to remove the old file from the store.
            Clear();
            base.OnDeleting();
        }
        protected override void Invalidate(bool disposing) {
            if (disposing && TempSourceStream != null) {
                TempSourceStream.Close();
                TempSourceStream = null;
            }
            base.Invalidate(disposing);
        }
        #region IFileData Members
        public void Clear() {
            //Dennis: When clearing the file name property we need to save the name of the old file to remove it from the store in the future. You can also setup a separate service for that.
            if (string.IsNullOrEmpty(tempFileName))
                tempFileName = RealFileName;
            FileName = string.Empty;
            Size = 0;
        }
        [Size(260)]
        public string FileName {
            get { return GetPropertyValue<string>(nameof(FileName)); }
            set { SetPropertyValue(nameof(FileName), value); }
        }
        [Browsable(false)]
        public Stream TempSourceStream {
            get { return tempSourceStream; }
            set {
                //Michael: The original Stream might be closed after a while (on the web too - T160753)
                if (value == null) {
                    tempSourceStream = null;
                } else {
                    if (value.Length > (long)int.MaxValue) throw new UserFriendlyException("File is too long");
                    tempSourceStream = new MemoryStream((int)value.Length);
                    FileSystemDataModule.CopyStream(value, tempSourceStream);
                    tempSourceStream.Position = 0;
                }
            }
        }
        //Dennis: Fires when uploading a file.
        void IFileData.LoadFromStream(string fileName,Stream source) {
            if (source.Length > 524288)
            { // 512 KB
                throw new UserFriendlyException("The file size must be less than or equal to 512 KB.");
            }
            // Validate file type (only images)
            string fileExtension = Path.GetExtension(fileName)?.ToLower();
            string[] allowedExtensions = { ".jpg", ".jpeg", ".png", ".bmp",".heif",".heic" }; // Add other image formats as needed

            if (!allowedExtensions.Contains(fileExtension))
            {
                throw new UserFriendlyException("Only image files (JPG, JPEG, PNG, BMP, heif, heic) are allowed.");
            }

            //Dennis: When assigning a new file we need to save the name of the old file to remove it from the store in the future.
            if (fileName != FileName) {// updated, old code was: if (string.IsNullOrEmpty(tempFileName))
                tempFileName = RealFileName;
            }
            FileName = fileName;
            TempSourceStream = source;
            Size = (int)TempSourceStream.Length;
            OnChanged();//T582918
        }
        //Dennis: Fires when saving or opening a file.
        void IFileData.SaveToStream(Stream destination) {
            try {
                if(!File.Exists(RealFileName)) {
                    return;
                }
                if (!string.IsNullOrEmpty(RealFileName)) {
                    if (destination == null)
                        FileSystemDataModule.OpenFileWithDefaultProgram(RealFileName);
                    else
                        FileSystemDataModule.CopyFileToStream(RealFileName, destination);
                }
                else if (TempSourceStream != null)
                    FileSystemDataModule.CopyStream(TempSourceStream, destination);
            } catch (DirectoryNotFoundException exc) {
                throw new UserFriendlyException(exc);
            } catch (FileNotFoundException exc) {
                throw new UserFriendlyException(exc);
            }
        }
        [Persistent]
        [RuleValueComparison("FileSizeValidation", DefaultContexts.Save, ValueComparisonType.LessThanOrEqual, 524288, // 512 KB
        CustomMessageTemplate = "The file size must be less than or equal to 512 KB.")]
        public int Size {
            get { return GetPropertyValue<int>(nameof(Size)); }
            private set { SetPropertyValue(nameof(Size), value); }
        }
        #endregion
        #region IEmptyCheckable Members
        public bool IsEmpty {
            //T153149
            get { return FileDataHelper.IsFileDataEmpty(this) || !(TempSourceStream!= null || File.Exists(RealFileName)); }
        }
        #endregion
    }
}