open pdf attachments in a new tab

app/coffee/utils.coffee

@@ -215,6 +215,9 @@ _.mixin
 isImage = (name) ->
     return name.match(/\.(jpe?g|png|gif|gifv|webm)/i) != null
 
+isPdf = (name) ->
+    return name.match(/\.(pdf)/i) != null
+
 patch = (oldImmutable, newImmutable) ->
     pathObj = {}
 
@@ -252,4 +255,5 @@ taiga.stripTags = stripTags
 taiga.replaceTags = replaceTags
 taiga.defineImmutableProperty = defineImmutableProperty
 taiga.isImage = isImage
+taiga.isPdf = isPdf
 taiga.patch = patch

app/modules/components/attachment-link/attachment-link.directive.coffee

@@ -28,6 +28,9 @@ AttachmentLinkDirective = ($parse, attachmentsPreviewService, lightboxService) -
                 scope.$apply ->
                     lightboxService.open($('tg-attachments-preview'))
                     attachmentsPreviewService.fileId = attachment.getIn(['file', 'id'])
+            else if taiga.isPdf(attachment.getIn(['file', 'name']))
+                event.preventDefault()
+                window.open(attachment.getIn(['file', 'url']))
 
         scope.$on "$destroy", -> el.off()
     return {