- Modified ImageModel: added File Type property;

- Images are now saved with the correct file type;
- Implemented CheckLocalImages: already downloaded images will not be downloaded again

ArtAPI/ArtStationAPI.cs

@@ -75,7 +75,8 @@ private async Task GetAssets(string hash_id, string name)
                                                            .Replace("/videos/","/images/")
                                                            .Replace("/panos/", "/images/"),     // workaround to download 4k images, maybe there's a better way, I might change this later
                         Name = name,
-                        ID = image["id"].ToString()
+                        ID = image["id"].ToString(),
+                        FileType = image["image_url"].ToString().Split('?')[0].Split('/').Last().Split('.')[1]
                     });
                 }
             }

ArtAPI/DeviantArtAPI.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Newtonsoft.Json.Linq;
@@ -60,9 +61,9 @@ protected override async Task GetImagesMetadataAsync(string apiUrl)
                     {
                         Url = image["content"]["src"].ToString(),
                         Name = image["title"].ToString(),
-                        ID = image["deviationid"].ToString()
-                    }
-                        );
+                        ID = image["deviationid"].ToString(),
+                        FileType = image["content"]["src"].ToString().Split('?')[0].Split('/').Last().Split('.')[1]  // maybe not the best way but surely the the easiest one
+                    });
                 }
                 if (responseJson["has_more"].ToString() == "False") return;
                 paginationOffset += Offset;
@@ -71,6 +72,7 @@ protected override async Task GetImagesMetadataAsync(string apiUrl)
 
         public override async Task<bool> auth(string refreshToken)
         {
+            if (IsLoggedIn) return true;
             var data = new Dictionary<string, string>()
             {
                 {"grant_type", "client_credentials" },
@@ -83,6 +85,8 @@ public override async Task<bool> auth(string refreshToken)
                 var response = await Client.PostAsync(AUTH_URL, content).ConfigureAwait(false);
                 var jsonResponse = JObject.Parse(await response.Content.ReadAsStringAsync().ConfigureAwait(false));
                 if (jsonResponse["status"].ToString() == "error") return false;
+                if (Client.DefaultRequestHeaders.Contains("Authorization"))
+                    Client.DefaultRequestHeaders.Remove("Authorization");
                 Client.DefaultRequestHeaders.Add("Authorization", $"Bearer {jsonResponse["access_token"]}");
             }
             catch(HttpRequestException)

ArtAPI/IRequestArt.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Threading;
@@ -131,6 +132,7 @@ protected async Task DownloadImagesAsync()
                 OnDownloadStateChanged(new DownloadStateChangedEventArgs(State.DownloadCanceled, "No images to download"));
                 Clear(); return;
             }
+            CheckLocalImages();
             OnDownloadStateChanged(new DownloadStateChangedEventArgs(State.DownloadRunning, TotalImageCount: TotalImageCount));
             cts = new CancellationTokenSource();
             using var ss = new SemaphoreSlim(ConcurrentTasks);
@@ -175,7 +177,7 @@ protected async Task DownloadAsync(ImageModel image, string savePath)
             var specialChars = new List<string>() { @"\", "/", ":", "*", "?", "\"", "<", ">", "|" };
             var imageName = image.Name;
             specialChars.ForEach(c => imageName = imageName.Replace(c, ""));  // remove all the nasty characters that can cause trouble
-            var imageSavePath = Path.Combine(savePath, $"{imageName}_{image.ID}.jpg");
+            var imageSavePath = Path.Combine(savePath, $"{imageName}_{image.ID}.{image.FileType}");
             const int tries = NumberOfDLAttempts;
             try
             {
@@ -221,11 +223,12 @@ private void Clear()
             ImagesToDownload.Clear();
         }
         /// <summary>
-        /// checks if there're already pictures saved locally and removes them from the list <see cref="ImagesToDownload"/>
+        /// checks if there are already pictures saved locally and removes them from the list <see cref="ImagesToDownload"/>
         /// </summary>
         private void CheckLocalImages()
         {
-            throw new NotImplementedException();
+            var localImages = Directory.GetFiles(ArtistDirSavepath).Select(Path.GetFileNameWithoutExtension).ToArray();
+            ImagesToDownload.RemoveAll(image => localImages.Contains($"{image.Name}_{image.ID}"));
         }
 
         public void CancelDownload()

ArtAPI/PixivAPI.cs

@@ -126,11 +126,8 @@ private async Task GetImageURLsWithoutLoginAsync(string illustProject)
                         {
                             Url = img_url["url_big"].ToString(),
                             Name = illustDetails["title"].ToString(),
-                            ID = img_url["url_big"].ToString()
-                                                   .Split('/')
-                                                   .Last()
-                                                   .Replace(".png", string.Empty)
-                                                   .Replace(".jpg", string.Empty)
+                            ID = img_url["url_big"].ToString().Split('/').Last().Split('.')[0],
+                            FileType = img_url["url_big"].ToString().Split('/').Last().Split('.')[1]
                         });
                     }
                 }
@@ -143,7 +140,8 @@ private async Task GetImageURLsWithoutLoginAsync(string illustProject)
                     {
                         Url = illustDetails["url_big"].ToString(),
                         Name = illustDetails["title"].ToString(),
-                        ID = illustDetails["id"].ToString()
+                        ID = illustDetails["id"].ToString(),
+                        FileType = illustDetails["url_big"].ToString().Split('/').Last().Split('.')[1]
                     });
                 }
             }
@@ -157,34 +155,39 @@ private void GetImageURLsWithLogin(JObject responseJson)
                 {
                     foreach (var img_url in IllustDetails["meta_pages"])
                     {
-                        ImagesToDownload.Add(new ImageModel()
+                        lock (ImagesToDownload)
                         {
-                            Url = img_url["image_urls"]["original"].ToString(),
-                            Name = IllustDetails["title"].ToString(),
-                            ID = img_url["image_urls"]["original"].ToString()
-                                .Split('/')
-                                .Last()
-                                .Replace(".png", string.Empty)
-                                .Replace(".jpg", string.Empty)
-                        });
+                            ImagesToDownload.Add(new ImageModel()
+                            {
+                                Url = img_url["image_urls"]["original"].ToString(),
+                                Name = IllustDetails["title"].ToString(),
+                                ID = img_url["image_urls"]["original"].ToString().Split('/').Last().Split('.')[0],
+                                FileType = img_url["image_urls"]["original"].ToString().Split('/').Last().Split('.')[1]
+                            });
+                        }
 
                     }
                 }
                 else
                 {
-                    ImagesToDownload.Add(new ImageModel()
+                    lock (ImagesToDownload)
                     {
-                        Url = IllustDetails["meta_single_page"]["original_image_url"].ToString(),
-                        Name = IllustDetails["title"].ToString(),
-                        ID = IllustDetails["id"].ToString()
-                    });
+                        ImagesToDownload.Add(new ImageModel()
+                        {
+                            Url = IllustDetails["meta_single_page"]["original_image_url"].ToString(),
+                            Name = IllustDetails["title"].ToString(),
+                            ID = IllustDetails["id"].ToString(),
+                            FileType = IllustDetails["meta_single_page"]["original_image_url"].ToString().Split('/').Last().Split('.')[1]
+                        });
+                    }
 
                 }
             }
         }
 
         public override async Task<bool> auth(string refreshToken)
         {
+            if (IsLoggedIn) return true;
             var clientTime = DateTime.UtcNow.ToString("s") + "+00:00";
             var data = new Dictionary<string, string>()
             {
@@ -208,6 +211,8 @@ public override async Task<bool> auth(string refreshToken)
                 var accessToken = jsonResponse["response"]["access_token"]?.ToString() ??
                                   throw new Exception("Bad API Response");
                 RefreshToken = jsonResponse["response"]["refresh_token"].ToString();
+                if (Client.DefaultRequestHeaders.Contains("Authorization"))
+                    Client.DefaultRequestHeaders.Remove("Authorization");
                 Client.DefaultRequestHeaders.Add("Authorization", $"Bearer {accessToken}");
             }
             catch (HttpRequestException)
@@ -243,6 +248,8 @@ public override async Task<string> login(string username, string password)
                 var accessToken = jsonResponse["response"]["access_token"]?.ToString() ??
                                   throw new Exception("Bad API Response");
                 RefreshToken = jsonResponse["response"]["refresh_token"].ToString();
+                if (Client.DefaultRequestHeaders.Contains("Authorization"))
+                    Client.DefaultRequestHeaders.Remove("Authorization");
                 Client.DefaultRequestHeaders.Add("Authorization", $"Bearer {accessToken}");
             }
             catch (HttpRequestException)

ArtAPI/models.cs

@@ -17,5 +17,9 @@ public class ImageModel
         /// platform-specific(Artstation, Deviantart, Pixiv...etc) ID of the image
         /// </summary>
         public string ID { get; set; }
+        /// <summary>
+        /// file type of the image (png, jpg, gif)
+        /// </summary>
+        public string FileType { get; set; } = "jpg";
     }
 }