Centralize sorting code

lib/core/notes_cache.dart

@@ -54,59 +54,19 @@ class NotesCache {
     }
   }
 
-  Future buildCache(NotesFolder rootFolder, SortingMode sortOrder) {
+  Future buildCache(NotesFolder rootFolder, SortingMode sortingMode) {
     print("Saving the NotesCache");
     // FIXME: This could be optimized quite a bit
     var files = rootFolder.getAllNotes();
     assert(files.every((n) => n.loadState == NoteLoadState.Loaded));
 
-    files.sort(_buildSortingFunc(sortOrder));
+    files.sort(sortingMode.sortingFunction());
     files = files.sublist(0, 10);
     var fileList = files.map((f) => f.filePath).toList();
 
     return saveToDisk(fileList);
   }
 
-  Function _buildSortingFunc(SortingMode order) {
-    switch (order) {
-      case SortingMode.Modified:
-        return (Note a, Note b) {
-          var aDt = a.modified ?? a.fileLastModified;
-          var bDt = b.modified ?? b.fileLastModified;
-          if (aDt == null && bDt != null) {
-            return -1;
-          }
-          if (aDt != null && bDt == null) {
-            return -1;
-          }
-          if (bDt == null || aDt == null) {
-            return 0;
-          }
-          return bDt.compareTo(aDt);
-        };
-
-      // FIXE: We should have an actual created date!
-      case SortingMode.Created:
-        return (Note a, Note b) {
-          var aDt = a.created ?? a.fileLastModified;
-          var bDt = b.created ?? b.fileLastModified;
-          if (aDt == null && bDt != null) {
-            return -1;
-          }
-          if (aDt != null && bDt == null) {
-            return -1;
-          }
-          if (bDt == null || aDt == null) {
-            return 0;
-          }
-          return bDt.compareTo(aDt);
-        };
-    }
-
-    assert(false, "Why is the sorting Func nill?");
-    return () => {};
-  }
-
   @visibleForTesting
   Future<List<String>> loadFromDisk() async {
     String contents = "";

lib/core/sorted_notes_folder.dart

@@ -9,16 +9,21 @@ class SortedNotesFolder
     with NotesFolderNotifier
     implements NotesFolderReadOnly {
   final NotesFolder folder;
-  SortingMode sortingMode;
+
+  SortingMode _sortingMode;
+  NoteSortingFunction _sortFunc;
 
   List<Note> _notes = [];
 
   SortedNotesFolder({
     @required this.folder,
-    @required this.sortingMode,
+    @required SortingMode sortingMode,
   }) {
+    _sortingMode = sortingMode;
+    _sortFunc = _sortingMode.sortingFunction();
+
     _notes = List<Note>.from(folder.notes);
-    _notes.sort(_compare);
+    _notes.sort(_sortFunc);
 
     folder.addFolderAddedListener(_folderAddedListener);
     folder.addFolderRemovedListener(_folderRemovedListener);
@@ -56,7 +61,7 @@ class SortedNotesFolder
     var i = 0;
     for (; i < _notes.length; i++) {
       var n = _notes[i];
-      if (_compare(n, note) > 0) {
+      if (_sortFunc(n, note) > 0) {
         break;
       }
     }
@@ -75,48 +80,10 @@ class SortedNotesFolder
   }
 
   void _entityChanged() {
-    _notes.sort(_compare);
+    _notes.sort(_sortFunc);
     notifyListeners();
   }
 
-  int _compare(Note a, Note b) {
-    switch (sortingMode) {
-      case SortingMode.Created:
-        // vHanda FIXME: We should use when the file was created in the FS, but that doesn't
-        //               seem to be acessible via dart
-        var aDt = a.created ?? a.fileLastModified;
-        var bDt = b.created ?? b.fileLastModified;
-        if (aDt == null && bDt != null) {
-          return -1;
-        }
-        if (aDt != null && bDt == null) {
-          return -1;
-        }
-        if (bDt == null || aDt == null) {
-          return 0;
-        }
-        return bDt.compareTo(aDt);
-
-      case SortingMode.Modified:
-        var aDt = a.modified ?? a.fileLastModified;
-        var bDt = b.modified ?? b.fileLastModified;
-        if (aDt == null && bDt != null) {
-          return -1;
-        }
-        if (aDt != null && bDt == null) {
-          return -1;
-        }
-        if (bDt == null || aDt == null) {
-          return 0;
-        }
-        if (bDt == null || aDt == null) {
-          return 0;
-        }
-        return bDt.compareTo(aDt);
-    }
-    return 0;
-  }
-
   @override
   List<Note> get notes => _notes;
 
@@ -127,8 +94,9 @@ class SortedNotesFolder
   bool get isEmpty => folder.isEmpty;
 
   void changeSortingMode(SortingMode sm) {
-    sortingMode = sm;
+    _notes.sort(_sortFunc);
-    _notes.sort(_compare);
     notifyListeners();
   }
+
+  SortingMode get sortingMode => _sortingMode;
 }

lib/core/sorting_mode.dart

@@ -1,3 +1,7 @@
+import 'package:gitjournal/core/note.dart';
+
+typedef NoteSortingFunction = int Function(Note a, Note b);
+
 class SortingMode {
   static const Modified = SortingMode("Last Modified", "Modified");
   static const Created = SortingMode("Created", "Created");
@@ -43,4 +47,46 @@ class SortingMode {
     assert(false, "SortingMode toString should never be called");
     return "";
   }
+
+  NoteSortingFunction sortingFunction() {
+    switch (_str) {
+      case "Created":
+        return (Note a, Note b) {
+          // vHanda FIXME: We should use when the file was created in the FS, but that doesn't
+          //               seem to be acessible via dart
+          var aDt = a.created ?? a.fileLastModified;
+          var bDt = b.created ?? b.fileLastModified;
+          if (aDt == null && bDt != null) {
+            return -1;
+          }
+          if (aDt != null && bDt == null) {
+            return -1;
+          }
+          if (bDt == null || aDt == null) {
+            return 0;
+          }
+          return bDt.compareTo(aDt);
+        };
+
+      case "Modified":
+      default:
+        return (Note a, Note b) {
+          var aDt = a.modified ?? a.fileLastModified;
+          var bDt = b.modified ?? b.fileLastModified;
+          if (aDt == null && bDt != null) {
+            return -1;
+          }
+          if (aDt != null && bDt == null) {
+            return -1;
+          }
+          if (bDt == null || aDt == null) {
+            return 0;
+          }
+          if (bDt == null || aDt == null) {
+            return 0;
+          }
+          return bDt.compareTo(aDt);
+        };
+    }
+  }
 }