Improves detection in liked-by downloader

- Uses a more generic regex pattern for matching images and videos in
the TumblrLikedByDownloader (#77).

src/TumblThree/TumblThree.Applications/Downloader/TumblrLikedByDownloader.cs

@@ -75,15 +75,6 @@ private string ResizeTumblrImageUrl(string imageUrl)
                 .ToString();
         }
 
-        /// <returns>
-        ///     Return the url without the size and type suffix (e.g.
-        ///     https://68.media.tumblr.com/51a99943f4aa7068b6fd9a6b36e4961b/tumblr_mnj6m9Huml1qat3lvo1).
-        /// </returns>
-        protected override string GetCoreImageUrl(string url)
-        {
-            return url.Split('_')[0] + "_" + url.Split('_')[1];
-        }
-
         protected override bool CheckIfFileExistsInDirectory(string url)
         {
             string fileName = url.Split('/').Last();
@@ -199,10 +190,13 @@ private void AddPhotoUrlToDownloadList(string document, IList<string> tags)
         {
             if (blog.DownloadPhoto)
             {
-                var regex = new Regex("data-big-photo=\"(.*)\" ");
+                var regex = new Regex("\"http[\\S]*media.tumblr.com[\\S]*(jpg|png|gif)\"");
                 foreach (Match match in regex.Matches(document))
                 {
-                    string imageUrl = match.Groups[1].Value;
+                    string imageUrl = match.Groups[0].Value;
+                    if (imageUrl.Contains("avatar") || imageUrl.Contains("previews"))
+                        continue;                    
+                    imageUrl = imageUrl.Substring(1, imageUrl.Length - 2);
                     if (blog.SkipGif && imageUrl.EndsWith(".gif"))
                     {
                         continue;
@@ -218,10 +212,11 @@ private void AddVideoUrlToDownloadList(string document, IList<string> tags)
         {
             if (blog.DownloadVideo)
             {
-                var regex = new Regex("<source src=\"(.*)\" type=\"video/mp4\"");
+                var regex = new Regex("\"http[\\S]*.com/video_file/[\\S]*\"");
                 foreach (Match match in regex.Matches(document))
                 {
-                    string videoUrl = match.Groups[1].Value;
+                    string videoUrl = match.Groups[0].Value;
+                    videoUrl = videoUrl.Substring(1, videoUrl.Length - 2);
                     // FIXME: postId
                     if (shellService.Settings.VideoSize == 1080)
                     {