generate permanent link for thread/comment on client side

lms/static/coffee/src/discussion/content.coffee

@@ -367,6 +367,15 @@ initializeFollowThread = (thread) ->
 
     MathJax.Hub.Queue ["Typeset", MathJax.Hub, $contentBody.attr("id")]
     id = $content.attr("_id")
+
+    discussion_id = $content.parents(".discussion").attr("_id")
+    if $content.hasClass("thread")
+      permalink = Discussion.urlFor("permanent_link_thread", discussion_id, id)
+    else
+      thread_id = $content.parents(".thread").attr("_id")
+      permalink = Discussion.urlFor("permanent_link_comment", discussion_id, thread_id, id)
+    $local(".discussion-permanent-link").attr "href", permalink
+
     if not Discussion.getContentInfo id, 'editable'
       $local(".discussion-edit").remove()
     if not Discussion.getContentInfo id, 'can_reply'

lms/static/coffee/src/discussion/utils.coffee

@@ -16,7 +16,7 @@ wmdEditors = {}
             .addClass(cls).html(txt)
             .click -> handler(this)
     
-  urlFor: (name, param, param1) ->
+  urlFor: (name, param, param1, param2) ->
     {
       follow_discussion      : "/courses/#{$$course_id}/discussion/#{param}/follow"
       unfollow_discussion    : "/courses/#{$$course_id}/discussion/#{param}/unfollow"
@@ -43,6 +43,8 @@ wmdEditors = {}
       tags_autocomplete      : "/courses/#{$$course_id}/discussion/threads/tags/autocomplete"
       retrieve_discussion    : "/courses/#{$$course_id}/discussion/forum/#{param}/inline"
       retrieve_single_thread : "/courses/#{$$course_id}/discussion/forum/#{param}/threads/#{param1}"
+      permanent_link_thread  : "/courses/#{$$course_id}/discussion/forum/#{param}/threads/#{param1}"
+      permanent_link_comment : "/courses/#{$$course_id}/discussion/forum/#{param}/threads/#{param1}##{param2}"
     }[name]
 
   safeAjax: (params) ->

lms/templates/discussion/_thread.html

@@ -88,6 +88,7 @@
     ${render_info(content)}
     ${render_link("discussion-link discussion-reply discussion-reply-" + type, "Reply")}
     ${render_link("discussion-link discussion-edit", "Edit")}
+    ${render_link("discussion-link discussion-permanent-link", "Permanent Link")}
 
     <span class="discussion-endorse-control">
       % if content.get('endorsed', False):