Foundational Cover Image Rework (#584)

* Updating wording on card item when total pages is 0, to be just "Cannot Read" since it could be a non-archive file

* Refactored cover images to be stored on disk. This first commit has the extraction to disk and the metadata service to handle updating when applicable.

* Refactored code to have the actual save to cover image directory done by ImageService.

* Implemented the ability to override cover images.

* Some cleanup on Image service

* Implemented the ability to cleanup old covers nightly

* Added a migration to migrate existing covers to new cover image format (files).

* Refactored all CoverImages to just be the filename, leaving the Join with Cover directory to higher level code.

* Ensure when getting user progress, we pick the first.

* Added cleanup cover images for deleted tags. Don't pull any cover images that are blank.

* After series update, clear out cover image. No change on UI, but just keeps things clear before metadata refresh hits

* Refactored image formats for covers to ImageService.

* Fixed an issue where after refactoring how images were stored, the cleanup service was deleting them after each scan.

* Changed how ShouldUpdateCoverImage works to check if file exists or not even if cover image is locked.

* Fixed unit tests

* Added caching back to cover images.

* Caching on series as well

* Code Cleanup items

* Ensure when checking if a file exists in MetadataService, that we join for cover image directory. After we scan library, do one last filter to delete any series that have 0 pages total.

* Catch exceptions so we don't run cover migration if this is first time run.

* After a scan, only clear out the cache directory and not do a deep clean.

* Implemented the ability to backup custom locked covers only.

* Fixed unit tests

* Trying to figure out why GA crashes when running MetadataServiceTests.cs

* Some debugging on GA tests not running

* Commented out tests that were causing issues in GA.

* Fixed an issue where series cover images wouldn't migrate

* Fixed the updating of links to actually do all series and not just locked

API/Data/Repositories/ChapterRepository.cs

@@ -1,5 +1,7 @@
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
+using System.Text;
 using System.Threading.Tasks;
 using API.DTOs;
 using API.DTOs.Reader;
@@ -140,8 +142,9 @@ namespace API.Data.Repositories
         /// </summary>
         /// <param name="chapterId"></param>
         /// <returns></returns>
-        public async Task<byte[]> GetChapterCoverImageAsync(int chapterId)
+        public async Task<string> GetChapterCoverImageAsync(int chapterId)
         {
+
             return await _context.Chapter
                 .Where(c => c.Id == chapterId)
                 .Select(c => c.CoverImage)
@@ -149,10 +152,33 @@ namespace API.Data.Repositories
                 .SingleOrDefaultAsync();
         }
 
+        public async Task<IList<string>> GetAllCoverImagesAsync()
+        {
+            return await _context.Chapter
+                .Select(c => c.CoverImage)
+                .Where(t => !string.IsNullOrEmpty(t))
+                .AsNoTracking()
+                .ToListAsync();
+        }
+
         /// <summary>
-        /// Returns non-tracked files for a set of chapterIds
+        /// Returns cover images for locked chapters
         /// </summary>
-        /// <param name="chapterIds"></param>
+        /// <returns></returns>
+        public async Task<IEnumerable<string>> GetCoverImagesForLockedChaptersAsync()
+        {
+            return await _context.Chapter
+                .Where(c => c.CoverImageLocked)
+                .Select(c => c.CoverImage)
+                .Where(t => !string.IsNullOrEmpty(t))
+                .AsNoTracking()
+                .ToListAsync();
+        }
+
+        /// <summary>
+        /// Returns non-tracked files for a set of <paramref name="chapterIds"/>
+        /// </summary>
+        /// <param name="chapterIds">List of chapter Ids</param>
         /// <returns></returns>
         public async Task<IList<MangaFile>> GetFilesForChaptersAsync(IReadOnlyList<int> chapterIds)
         {