Cleaning up code with Ember.computed

refactoring.diff

device: DS.belongsTo('device'),
 
-  isNotIngestable: function() {
-    return Ember.isNone(this.get('device'));
-  }.property('device'),
-
-  isScanning: function() {
-    var device = this.get('device');
-    var deviceIsConnected = !Ember.isNone(device);
-    var deviceHasntFoundFiles = device && Ember.isNone(device.get('files'));
-
-    return (deviceIsConnected && deviceHasntFoundFiles);
-  }.property('device', 'device.files'),
-
-  isEmpty: function() {
-    var device = this.get('device');
-    var deviceIsConnected = !Ember.isNone(device);
-    var deviceHasNoFiles = device && device.get('hasNoFiles');
-
-    return deviceIsConnected && deviceHasNoFiles;
-  }.property('device.files'),
-
-  isIngestable: function() {
-    var device = this.get('device');
-    var deviceIsConnected = !Ember.isNone(device);
-    var deviceHasFiles = device && device.get('hasFiles');
-    var deviceHasNoIngest = device && Ember.isNone(device.get('ingest'));
-
-    return deviceIsConnected && deviceHasFiles && deviceHasNoIngest;
-  }.property('device.files', 'device.ingest'),
+  hasNoDevice: Ember.computed.none('device'),
+  deviceIsConnected: Ember.computed.not('hasNoDevice'),
+  hasNoIngest: Ember.computed.none('ingest'),
+
+  isNotIngestable: Ember.computed.alias('hasNoDevice'),
+  isScanning: Ember.computed.alias('device.scanningForFiles'),
+  isEmpty: Ember.computed.alias('device.hasNoFiles'),
+  isIngestable: Ember.computed.and('device.hasFiles', 'hasNoIngest'),
 
   state: function() {
     if (this.get('isNotIngestable')) {return 'not-ingestable';}