Issue #431 - Prevent comment link expiry - Added functionality for comment linking

*   `media.html`
    *   Changed comment textarea handle from `comment` => `field_comment`
    *   Active comment is hilighted with the CSS class name `comment_active`
    	and also with the hyperlink anchor #comment
    *   Changed media.html so that pagination always uses
    	Route('mediagoblin.user_pages.media_home') as base_url
*   `user_pages/forms.py`
    *   Renamed MediaComment form field `comment` => `field_comment`
*   `user_pages/routing.py`
    *   Added route for `/u/joar/m/123..456/c/234..567/`, points to `media_home`
*   `user_pages/views.py`
    *   `media_home` now checks if the request contains a comment id parameter
        then acts accordingly with pagination whether to call it with a
        `jump_to_id` or not.
    *	`media_post_comment` - Updated MediaCommentForm field name
        `comment` => `field_comment`
*   `util.py`
    *   `redirect` now supports querystring arguments. - NOT USED (should we
        keep it? I think so, it might be useful, sometime [don't call me a
        code hoarder]).
    *   `Pagination.__init__` now accepts one further argument, the `jump_to_id`.
        It assist the comment linking functionality in finding and returning the
        proper page for a comment.
        This feature will work for all kinds of objects. It might not be
        optimal, but it is well functional :)

1 files changed, 32 insertions, 4 deletions

diff --git a/mediagoblin/util.py b/mediagoblin/util.py
index ab219df0..7b1e4a2a 100644
--- a/mediagoblin/util.py
+++ b/mediagoblin/util.py
@@ -14,6 +14,8 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+from __future__ import division
+
 from email.MIMEText import MIMEText
 import gettext
 import pkg_resources
@@ -21,7 +23,7 @@ import smtplib
 import sys
 import re
 import urllib
-from math import ceil
+from math import ceil, floor
 import copy
 
 from babel.localedata import exists
@@ -35,6 +37,8 @@ from mediagoblin import mg_globals
 from mediagoblin import messages
 from mediagoblin.db.util import ObjectId
 
+from itertools import izip, count
+
 TESTS_ENABLED = False
 def _activate_testing():
     """
@@ -133,7 +137,16 @@ def render_to_response(request, template, context):
 
 def redirect(request, *args, **kwargs):
     """Returns a HTTPFound(), takes a request and then urlgen params"""
-    return exc.HTTPFound(location=request.urlgen(*args, **kwargs))
+    
+    querystring = None
+    if kwargs.get('querystring'):
+        querystring = kwargs.get('querystring')
+        del kwargs['querystring']
+
+    return exc.HTTPFound(
+        location=''.join([
+                request.urlgen(*args, **kwargs),
+                querystring if querystring else '']))
 
 
 def setup_user_in_request(request):
@@ -418,7 +431,8 @@ class Pagination(object):
     get actual data slice through __call__().
     """
 
-    def __init__(self, page, cursor, per_page=PAGINATION_DEFAULT_PER_PAGE):
+    def __init__(self, page, cursor, per_page=PAGINATION_DEFAULT_PER_PAGE,
+                 jump_to_id=False):
         """
         Initializes Pagination
 
@@ -426,11 +440,25 @@ class Pagination(object):
          - page: requested page
          - per_page: number of objects per page
          - cursor: db cursor 
+         - jump_to_id: ObjectId, sets the page to the page containing the object
+           with _id == jump_to_id.
         """
-        self.page = page    
+        self.page = page
         self.per_page = per_page
         self.cursor = cursor
         self.total_count = self.cursor.count()
+        self.active_id = None
+
+        if jump_to_id:
+            cursor = copy.copy(self.cursor)
+
+            for (doc, increment) in izip(cursor, count(0)):
+                if doc['_id'] == jump_to_id:
+                    self.page = 1 + int(floor(increment / self.per_page))
+
+                    self.active_id = jump_to_id
+                    break
+
 
     def __call__(self):
         """