Fix title sort bug, invalidate titles of the Library

Refactor remove cache

src/library/entry.cr

@@ -90,7 +90,8 @@ class Entry
     end
 
     @book.entry_sort_title_cache = nil
-    @book.remove_sorted_caches [SortMethod::Auto, SortMethod::Title], username
+    @book.remove_sorted_entries_cache [SortMethod::Auto, SortMethod::Title],
+      username
   end
 
   def sort_title_db

src/library/title.cr

@@ -320,7 +320,13 @@ class Title
       @sort_title = sort_title
     end
 
-    remove_sorted_caches [SortMethod::Auto, SortMethod::Title], username
+    if parents.size > 0
+      target = parents[-1].titles
+    else
+      target = Library.default.titles
+    end
+    remove_sorted_titles_cache target,
+      [SortMethod::Auto, SortMethod::Title], username
   end
 
   def sort_title_db
@@ -612,7 +618,8 @@ class Title
     zip + titles.flat_map &.deep_entries_with_date_added
   end
 
-  def remove_sorted_caches(sort_methods : Array(SortMethod), username : String)
+  def remove_sorted_entries_cache(sort_methods : Array(SortMethod),
+                                  username : String)
     [false, true].each do |ascend|
       sort_methods.each do |sort_method|
         sorted_entries_cache_key =
@@ -621,15 +628,14 @@ class Title
         LRUCache.invalidate sorted_entries_cache_key
       end
     end
+  end
+
+  def remove_sorted_caches(sort_methods : Array(SortMethod), username : String)
+    remove_sorted_entries_cache sort_methods, username
     parents.each do |parent|
-      [false, true].each do |ascend|
-        sort_methods.each do |sort_method|
-          sorted_titles_cache_key = SortedTitlesCacheEntry.gen_key username,
-            parent.titles, SortOptions.new(sort_method, ascend)
-          LRUCache.invalidate sorted_titles_cache_key
-        end
-      end
+      remove_sorted_titles_cache parent.titles, sort_methods, username
     end
+    remove_sorted_titles_cache Library.default.titles, sort_methods, username
   end
 
   def bulk_progress(action, ids : Array(String), username)

src/util/util.cr

@@ -91,25 +91,25 @@ def sort_titles(titles : Array(Title), opt : SortOptions, username : String)
   cached_titles = LRUCache.get cache_key
   return cached_titles if cached_titles.is_a? Array(Title)
 
-  ary = titles
-
   case opt.method
   when .time_modified?
-    ary.sort { |a, b| (a.mtime <=> b.mtime).or \
+    ary = titles.sort { |a, b| (a.mtime <=> b.mtime).or \
       compare_numerically a.sort_title, b.sort_title }
   when .progress?
-    ary.sort do |a, b|
+    ary = titles.sort do |a, b|
       (a.load_percentage(username) <=> b.load_percentage(username)).or \
         compare_numerically a.sort_title, b.sort_title
     end
   when .title?
-    ary.sort { |a, b| compare_numerically a.sort_title, b.sort_title }
+    ary = titles.sort do |a, b|
+      compare_numerically a.sort_title, b.sort_title
+    end
   else
     unless opt.method.auto?
       Logger.warn "Unknown sorting method #{opt.not_nil!.method}. Using " \
                   "Auto instead"
     end
-    ary.sort { |a, b| compare_numerically a.sort_title, b.sort_title }
+    ary = titles.sort { |a, b| compare_numerically a.sort_title, b.sort_title }
   end
 
   ary.reverse! unless opt.not_nil!.ascend
@@ -118,6 +118,18 @@ def sort_titles(titles : Array(Title), opt : SortOptions, username : String)
   ary
 end
 
+def remove_sorted_titles_cache(titles : Array(Title),
+                               sort_methods : Array(SortMethod),
+                               username : String)
+  [false, true].each do |ascend|
+    sort_methods.each do |sort_method|
+      sorted_titles_cache_key = SortedTitlesCacheEntry.gen_key username,
+        titles, SortOptions.new(sort_method, ascend)
+      LRUCache.invalidate sorted_titles_cache_key
+    end
+  end
+end
+
 class String
   # Returns the similarity (in [0, 1]) of two paths.
   # For the two paths, separate them into arrays of components, count the