1 files changed, 109 insertions, 0 deletions
diff --git a/mediagoblin/tools/pagination.py b/mediagoblin/tools/pagination.py
new file mode 100644
index 00000000..859b60fb
--- /dev/null
+++ b/mediagoblin/tools/pagination.py
@@ -0,0 +1,109 @@
+# GNU MediaGoblin -- federated, autonomous media hosting
+# Copyright (C) 2011 MediaGoblin contributors.  See AUTHORS.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# 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/>.
+
+import urllib
+import copy
+from math import ceil, floor
+from itertools import izip, count
+
+PAGINATION_DEFAULT_PER_PAGE = 30
+
+class Pagination(object):
+    """
+    Pagination class for mongodb queries.
+
+    Initialization through __init__(self, cursor, page=1, per_page=2),
+    get actual data slice through __call__().
+    """
+
+    def __init__(self, page, cursor, per_page=PAGINATION_DEFAULT_PER_PAGE,
+                 jump_to_id=False):
+        """
+        Initializes Pagination
+
+        Args:
+         - 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.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):
+        """
+        Returns slice of objects for the requested page
+        """
+        return self.cursor.skip(
+            (self.page - 1) * self.per_page).limit(self.per_page)
+
+    @property
+    def pages(self):
+        return int(ceil(self.total_count / float(self.per_page)))
+
+    @property
+    def has_prev(self):
+        return self.page > 1
+
+    @property
+    def has_next(self):
+        return self.page < self.pages
+
+    def iter_pages(self, left_edge=2, left_current=2,
+                   right_current=5, right_edge=2):
+        last = 0
+        for num in xrange(1, self.pages + 1):
+            if num <= left_edge or \
+               (num > self.page - left_current - 1 and \
+                num < self.page + right_current) or \
+               num > self.pages - right_edge:
+                if last + 1 != num:
+                    yield None
+                yield num
+                last = num
+
+    def get_page_url_explicit(self, base_url, get_params, page_no):
+        """ 
+        Get a page url by adding a page= parameter to the base url
+        """ 
+        new_get_params = copy.copy(get_params or {})
+        new_get_params['page'] = page_no
+        return "%s?%s" % (
+            base_url, urllib.urlencode(new_get_params))
+
+    def get_page_url(self, request, page_no):
+        """ 
+        Get a new page url based of the request, and the new page number.
+
+        This is a nice wrapper around get_page_url_explicit()
+        """ 
+        return self.get_page_url_explicit(
+            request.path_info, request.GET, page_no)