Simplify tab counts calculation and move into a separate module

Refactor some repetition in the functions that produced the counts for
the Annotations, Page Notes and Orphans tabs and extract it into a
separate module where it is easier to test.

Moving this into a single function also makes it easier to memoize
later, so we can avoid recalculating it when the list of annotations has
not changed between two app states.

h/static/scripts/tab-counts.js

+'use strict';
+
+var metadata = require('./annotation-metadata');
+
+function countIf(list, predicate) {
+  return list.reduce(function (count, item) {
+    return predicate(item) ? count + 1 : count;
+  }, 0);
+}
+
+/**
+ * Return a count of the number of Annotations, Page Notes, Orphans and
+ * annotations still being anchored in a set of `annotations`
+ */
+function tabCounts(annotations, opts) {
+  opts = opts || {separateOrphans: false};
+
+  var counts = {
+    notes: countIf(annotations, metadata.isPageNote),
+    annotations: countIf(annotations, metadata.isAnnotation),
+    orphans: countIf(annotations, metadata.isOrphan),
+    anchoring: countIf(annotations, metadata.isWaitingToAnchor),
+  };
+
+  if (opts.separateOrphans) {
+    return counts;
+  } else {
+    return Object.assign({}, counts, {
+      annotations: counts.annotations + counts.orphans,
+      orphans: 0,
+    });
+  }
+}
+
+module.exports = tabCounts;

h/static/scripts/test/tab-counts-test.js

+'use strict';
+
+var fixtures = require('./annotation-fixtures');
+var tabCounts = require('../tab-counts');
+
+describe('tabCounts', function () {
+  var annotation = Object.assign(fixtures.defaultAnnotation(), {$orphan:false});
+  var orphan = Object.assign(fixtures.defaultAnnotation(), {$orphan:true});
+
+  it('counts Annotations and Orphans together when the Orphans tab is not enabled', function () {
+    assert.deepEqual(tabCounts([annotation, orphan]), {
+      anchoring: 0,
+      annotations: 2,
+      notes: 0,
+      orphans: 0,
+    });
+  });
+
+  it('counts Annotations and Orphans separately when the Orphans tab is enabled', function () {
+    assert.deepEqual(tabCounts([annotation, orphan], {separateOrphans: true}), {
+      anchoring: 0,
+      annotations: 1,
+      notes: 0,
+      orphans: 1,
+    });
+  });
+});

h/static/scripts/widget-controller.js

@@ -5,6 +5,7 @@ var events = require('./events');
 var memoize = require('./util/memoize');
 var metadata = require('./annotation-metadata');
 var scopeTimeout = require('./util/scope-timeout');
+var tabCounts = require('./tab-counts');
 var uiConstants = require('./ui-constants');
 
 function firstKey(object) {
@@ -38,48 +39,6 @@ module.exports = function WidgetController(
   features, groups, rootThread, settings, streamer, streamFilter, store,
   VirtualThreadList
 ) {
-
-  /**
-   * Returns the number of annotations which are not yet anchored.
-   */
-  function countWaitingToAnchorAnnotations (annotations) {
-    var total = annotations.reduce(function (count, annotation) {
-      return annotation && metadata.isWaitingToAnchor(annotation) ? count + 1 : count;
-    }, 0);
-    return total;
-  }
-
-  /**
-   * Returns the number of top level annotations which are unanchored i.e orphans.
-   */
-  function countOrphans(annotations) {
-    var total = annotations.reduce(function (count, annotation) {
-      return annotation && metadata.isOrphan(annotation) ? count + 1 : count;
-    }, 0);
-    return total;
-  }
-
-  /**
-   * Returns the number of top level annotations which are of type annotations
-   * and not notes or replies.
-   */
-  function countAnnotations(annotations) {
-    var total = annotations.reduce(function (count, annotation) {
-      return annotation && metadata.isAnnotation(annotation) ? count + 1 : count;
-    }, 0);
-    return total;
-  }
-
-  /**
-   * Returns the number of top level annotations which are of type notes.
-   */
-  function countNotes(annotations) {
-    var total = annotations.reduce(function (count, annotation) {
-      return annotation && metadata.isPageNote(annotation) ? count + 1 : count;
-    }, 0);
-    return total;
-  }
-
   /**
    * Returns the height of the thread for an annotation if it exists in the view
    * or undefined otherwise.
@@ -114,19 +73,21 @@ module.exports = function WidgetController(
   // to reserve space for threads which are not actually rendered.
   var visibleThreads = new VirtualThreadList($scope, window, thread());
   var unsubscribeAnnotationUI = annotationUI.subscribe(function () {
-    visibleThreads.setRootThread(thread());
-    $scope.selectedTab = annotationUI.getState().selectedTab;
+    var state = annotationUI.getState();
 
-    $scope.waitingToAnchorAnnotations = countWaitingToAnchorAnnotations(annotationUI.getState().annotations) > 0;
+    visibleThreads.setRootThread(thread());
+    $scope.selectedTab = state.selectedTab;
 
-    $scope.totalNotes = countNotes(annotationUI.getState().annotations);
-    $scope.totalOrphans = countOrphans(annotationUI.getState().annotations);
+    var counts = tabCounts(state.annotations, {
+      separateOrphans: features.flagEnabled('orphans_tab'),
+    });
 
-    if (!features.flagEnabled('orphans_tab')) {
-      $scope.totalAnnotations = $scope.totalAnnotations + $scope.totalOrphans;
-    } else {
-      $scope.totalAnnotations = countAnnotations(annotationUI.getState().annotations);
-    }
+    Object.assign($scope, {
+      totalNotes: counts.notes,
+      totalAnnotations: counts.annotations,
+      totalOrphans: counts.orphans,
+      waitingToAnchorAnnotations: counts.anchoring > 0,
+    });
   });
 
   $scope.$on('$destroy', unsubscribeAnnotationUI);