Improve the multi-selection experience

New features:
- select all filtered cards
- assign or unassign a member to selected cards
- archive selected cards

This commit also fix the card sort indexes calculation when a multi-
selection is drag-dropped.

client/lib/escapeActions.js

@@ -153,6 +153,6 @@ Mousetrap.bindGlobal('esc', function() {
 $(document).on('click', function(evt) {
   if (evt.which === 1 &&
     $(evt.target).closest('a,button,.is-editable').length === 0) {
-    EscapeActions.clickExecute(evt, 'detailsPane');
+    EscapeActions.clickExecute(evt, 'multiselection');
   }
 });

client/lib/multiSelection.js

@@ -72,17 +72,21 @@ MultiSelection = {
     return this._isActive.get();
   },
 
+  count: function() {
+    return Cards.find(this.getMongoSelector()).count();
+  },
+
   isEmpty: function() {
-    return this._selectedCards.get().length === 0;
+    return this.count() === 0;
   },
 
   activate: function() {
     if (! this.isActive()) {
       EscapeActions.executeUpTo('detailsPane');
       this._isActive.set(true);
-      Sidebar.setView(this.sidebarView);
       Tracker.flush();
     }
+    Sidebar.setView(this.sidebarView);
   },
 
   disable: function() {
@@ -152,5 +156,7 @@ Blaze.registerHelper('MultiSelection', MultiSelection);
 
 EscapeActions.register('multiselection',
   function() { MultiSelection.disable(); },
-  function() { return MultiSelection.isActive(); }
+  function() { return MultiSelection.isActive(); }, {
+    noClickEscapeOn: '.js-minicard,.js-board-sidebar-content'
+  }
 );

client/lib/utils.js

@@ -37,23 +37,26 @@ Utils = {
   },
 
   // Determine the new sort index
-  getSortIndex: function(prevCardDomElement, nextCardDomElement) {
+  calculateIndex: function(prevCardDomElement, nextCardDomElement, nCards) {
+    nCards = nCards || 1;
+
     // If we drop the card to an empty column
     if (! prevCardDomElement && ! nextCardDomElement) {
-      return 0;
+      return {base: 0, increment: 1};
     // If we drop the card in the first position
     } else if (! prevCardDomElement) {
-      return Blaze.getData(nextCardDomElement).sort - 1;
+      return {base: Blaze.getData(nextCardDomElement).sort - 1, increment: -1};
     // If we drop the card in the last position
     } else if (! nextCardDomElement) {
-      return Blaze.getData(prevCardDomElement).sort + 1;
+      return {base: Blaze.getData(prevCardDomElement).sort + 1, increment: 1};
     }
     // In the general case take the average of the previous and next element
     // sort indexes.
     else {
       var prevSortIndex = Blaze.getData(prevCardDomElement).sort;
       var nextSortIndex = Blaze.getData(nextCardDomElement).sort;
-      return (prevSortIndex + nextSortIndex) / 2;
+      var increment = (nextSortIndex - prevSortIndex) / (nCards + 1);
+      return {base: prevSortIndex + increment, increment: increment};
     }
   }
 };