Test, fix limiting number of saved positions

lib/position-manager/position-data-manager.dart

@@ -61,7 +61,7 @@ class PositionDataManager extends IPositionDataManager {
 class HivePositionDataManager extends IPositionDataManager {
   static final positionHive = HiveImpl();
   static const positionBoxName = "positions";
-  static const int maxSavedPositions = 2000;
+  static const int maxSavedPositions = 200;
 
   Box<Position> positionBox;
   HivePositionDataManager();
@@ -120,22 +120,22 @@ class HivePositionDataManager extends IPositionDataManager {
       await positionBox.put(position.id.limitFromEnd(255), position);
     } else {
       // No need to clutter the DB with zeros - that's the default, anyway.
-      await positionBox.delete(position.id);
+      await positionBox.delete(position.id.limitFromEnd(255));
     }
   }
 
   /// Make sure we don't try to hold too many positions in memory.
   Future<void> _constrainBoxSize() async {
+    // E.g: There are 3 items, we're aloud max of 2, we need to delete 1.
     int amountPositionsToDelete = positionBox.length - maxSavedPositions;
 
     if (amountPositionsToDelete < 1) {
       return;
     }
 
     final positions = positionBox.values.toList();
-    positions.sort((p1, p2) =>
-        p2.createdDate.millisecondsSinceEpoch -
-        p1.createdDate.millisecondsSinceEpoch);
+
+    positions.sort((p1, p2) => p1.createdDate.compareTo(p2.createdDate));
     final positionsToDelete = positions.take(amountPositionsToDelete);
 
     await Stream.fromFutures(

lib/position-manager/position.dart

@@ -5,15 +5,19 @@ part 'position.g.dart';
 /// Keep track of the last position of an audio file.
 @HiveType(typeId: 0)
 class Position extends HiveObject {
-  Position({Duration position, String id}) {
+  Position({Duration position, this.id}) {
     if (position != null) {
       this.position = position;
     }
-    this.id = id;
+
+    _createdDate = DateTime.now().millisecondsSinceEpoch;
   }
 
   /// When the file was created, or the position was last updated.
-  DateTime get createdDate => DateTime.fromMillisecondsSinceEpoch(_createdDate);
+  /// If [_createdDate] isn't set, consider it as being 0, which makes the record very old, and will probably be
+  /// deleted soon.
+  DateTime get createdDate =>
+      DateTime.fromMillisecondsSinceEpoch(_createdDate ?? 0);
 
   Duration get position => Duration(milliseconds: _position ?? 0);
 
@@ -22,17 +26,13 @@ class Position extends HiveObject {
   }
 
   /// Expose the id whose position is being described, independent of hive storage.
-  String get id {
-    return key ?? _id;
-  }
-
-  set id(String id) => _id = id;
+  /// This is important because the hive id is truncated according to hive requirements.
+  @HiveField(2)
+  String id;
 
   @HiveField(0)
   int _position;
 
   @HiveField(1)
   int _createdDate;
-
-  String _id;
 }