MARKUS

using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.ComponentModel;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Media.Imaging;

namespace KCOM.PageManager

{

    public class PageStorage

    {

        private const int DEFUALT_TALK_PAGE_COUNT = 10;

        public event EventHandler<PageLoadCompletedEventArgs> PageLoadCompleted;

        List<int> WorkItems = new List<int>();

        ConcurrentBag<PageItem> fileItems = new ConcurrentBag<PageItem>();

        BackgroundWorker backgroundWorker;

        //List<PageItem> fileItems = new List<PageItem>();

        string _localStorage;

        string _fileExt;

        string _BaseUri;

        int _TotalPages;

        int _TakeCount;

        bool IsDownload = false;

        BitmapFrame PageImage;

        public PageStorage(string BaseUri, string localStoragePath,string fileExt,int totalPages,int takeCount = 5)

        {

            try

            {

                backgroundWorker = new BackgroundWorker {WorkerSupportsCancellation = true,WorkerReportsProgress = true};

                backgroundWorker.DoWork += BackgroundWorker_DoWork;

                backgroundWorker.ProgressChanged += BackgroundWorker_ProgressChanged;

                _fileExt = fileExt;

                _BaseUri = BaseUri;

                _localStorage = localStoragePath;

                _TotalPages = totalPages;

                _TakeCount = takeCount;

                System.IO.Directory.CreateDirectory(_localStorage);

                //backgroundWorker.RunWorkerAsync(new int[] { 1, 10 });

            }

            catch (Exception ex)

            {

                throw new Exception("PageStorage", ex);

            }

        }

        private void BackgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)

        {

            System.Diagnostics.Debug.WriteLine(_fileExt + ":" + e.ProgressPercentage.ToString() + "%");

        }

        private async void BackgroundWorker_DoWork(object sender, DoWorkEventArgs e)

        {

                while (WorkItems.Count > 0)

                {

                    if (!IsDownload)

                    {

                        int item = -1;

                        try

                        {

                            if (WorkItems.TryFrist(true,out item))

                            {

                                var result = await DownloadPageAsync(item, null);

                                if(!result.IsDownLoad)

                                {

                                    System.Threading.Thread.Sleep(100);

                                }

                            await Task.Delay(100);

                            //System.Threading.Thread.Sleep(10);

                            //backgroundWorker.ReportProgress(fileItems.Count / _TotalPages * 100);

                        }

                        }

                        catch (Exception ex)

                        {

                            System.Diagnostics.Debug.WriteLine(ex.ToString());

                        }

                    }

              }

      }

        public void ResetImage()

        {

            //if (PageImage != null)

            //{

            //    PageImage = null;

            //}

            //PageImage.CreateOptions = BitmapCreateOptions.IgnoreImageCache;

        }

        public async Task<BitmapFrame> GetPageImageAsync(System.Threading.CancellationToken cts,int PageNo,bool IsRestart =false)

        {

            try

            {

                var localUri = await GetPageUriAsync(null,PageNo);

                if (localUri != null || !cts.IsCancellationRequested)

                {

                    PageImage = BitmapFrame.Create(localUri, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);

                }

            }

            catch (Exception ex)

            {

                throw new Exception("GetPageImageAsync(int PageNo,bool IsRestart =false)", ex);

            }

            finally

            {

            }

            return PageImage;

        }

        private void DownloadWorkAsync(int startPage,int TakeCount)

        {

            lock(WorkItems)

            {

                WorkItems.AddRange(Enumerable.Range(startPage, TakeCount));

            }

            if (TakeCount == _TotalPages)

            {

                _TakeCount = 0;

            }

           // var files = fileItems.Select(x => x.PageNo);

            //for (int i = startPage; i < TakeCount + 1; i++)

            //{

            //    if (i < _TotalPages && !WorkItems.Contains(i) && !files.Contains(i))

            //    {

            //        WorkItems.Add(i);

            //       // System.Threading.Thread.Sleep(1);

            //    }

            //    else if(i == _TotalPages)

            //    {

            //        _TakeCount = 0;

            //    }

            //}

            if (!backgroundWorker.IsBusy && WorkItems.Count() > 0)

            {

                backgroundWorker.RunWorkerAsync();

            }

            //await Task.Delay(10);//  System.Threading.Thread.Sleep(10);

            //while (WorkItems.Count > 0)

            //{

            //    int item = -1;

            //    if (WorkItems.TryDequeue(out item))

            //    {

            //        var result = await DownloadPageAsync(item, null);

            //    }

            //}

        }

        public async Task<Uri> GetPageUriAsync( System.Threading.CancellationToken? cts, int PageNo, bool IsRestart = false)

        {

            Uri result = null;

            try

            {

                System.Diagnostics.Debug.WriteLine("GetPageAsync");

                var pageItem = await DownloadPageAsync(PageNo,cts);

                if (pageItem != null && 0 < _TakeCount && PageNo + 1 < _TotalPages)

                {

                    int takecount = _TakeCount;

                    if (_TotalPages < PageNo + 1 + takecount)

                    {

                        takecount = takecount - (PageNo + 1 + takecount - _TotalPages) -1;

                    }

                    DownloadWorkAsync(PageNo + 1, takecount);

                    //var takePageNoList = Enumerable.Range(PageNo + 1, _TakeCount);

                }

                result = pageItem.LocalUri;

            }

            catch (Exception ex)

            {

                if (cts != null)

                {

                    if (cts.Value.IsCancellationRequested)

                    {

                        return result;

                    }

                }

                if (!IsRestart)

                {

                    await Task.Delay(100);

                    result = await GetPageUriAsync(cts,PageNo, true);

                }

                //throw new Exception("GetPageAsync(string BasePageUri,int PageNo)", ex);

            }

            finally

            {

            }

            return result;

        }

        public async Task<PageItem> DownloadPageAsync(int PageNo,System.Threading.CancellationToken? cts)

        {

            PageItem result = new PageItem { PageNo = PageNo };

            try

            {

                var page = fileItems.Where(x => x.PageNo == PageNo).ToList();

                if (page.Count > 0)

                {

                    System.Diagnostics.Debug.WriteLine("DownloadPageAsync fileItems");

                    result = page.First();

                    /// 파일 체크 후 없으면 다시 다운로드

                    if (!System.IO.File.Exists(result.LocalFilePath))

                    {

                        //fileItems.(result);

                        result = await DownloadPageAsync(PageNo,cts);

                    }

                }

                else

                {

                    System.Diagnostics.Debug.WriteLine("DownloadPageAsync down");

                    string downloadFilePath = System.IO.Path.Combine(_localStorage, PageNo.ToString() + "." + _fileExt);

                    Uri originalUri = new Uri(_BaseUri.Replace("{PageNo}", PageNo.ToString()));

                    result = new PageItem

                    {

                        PageNo = PageNo,

                        OriginalUri = originalUri,

                        LocalUri = new Uri(downloadFilePath, UriKind.Absolute),

                        LocalFilePath = downloadFilePath

                    };

                    if(fileItems.Where(x => x.PageNo == PageNo).Count() == 0)

                    {

                        fileItems.Add(result);

                    }

                    using (System.Net.WebClient client = new System.Net.WebClient())

                    {

                        client.UseDefaultCredentials = true;

                        System.Net.IWebProxy webProxy = client.Proxy;

                        if (webProxy != null)

                        {

                            // Use the default credentials of the logged on user.

                            webProxy.Credentials = System.Net.CredentialCache.DefaultCredentials;

                        }

                        //client.DownloadFileCompleted += (snd, evt) =>

                        //{

                        //    //(snd as System.Net.WebClient).Dispose();

                        //};

                        if (cts != null)

                        {

                            client.DownloadProgressChanged += (snd, ect) =>

                            {

                                IsDownload = client.IsBusy;

                                if (cts.Value.IsCancellationRequested)

                                {

                                    client.CancelAsync();

                                }

                            };

                        }

                        client.DownloadFileCompleted += (snd, evt) =>

                        {

                            result.IsDownLoad = true;

                            System.Diagnostics.Debug.WriteLine("Download : " + downloadFilePath);

                            PageLoadCompleted?.Invoke(this, new PageLoadCompletedEventArgs(result));

                        };

                        await client.DownloadFileTaskAsync(originalUri, downloadFilePath);

                    }

                    //}

                    //System.Diagnostics.Debug.WriteLine("Download : " + result.LocalFilePath);

                }

            }

            catch (Exception ex)

            {

                throw new Exception("DownloadPageAsync : ", ex);

            }

            finally

            {

                IsDownload = false;

            }

            return result;

        }

        public void Clear()

        {

            try

            {

                ResetImage();

            }

            catch (Exception ex)

            {

                System.Diagnostics.Debug.WriteLine(ex.ToString());

            }

            try

            {

                backgroundWorker.CancelAsync();

                backgroundWorker.Dispose();

                foreach (var item in fileItems)

                {

                    System.IO.File.Delete(item.LocalFilePath);

                }

                System.IO.Directory.Delete(_localStorage, true);

            }

            catch (Exception ex)

            {

                System.Diagnostics.Debug.WriteLine(ex.ToString());

            }

        }

    }

}