--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/backend/AbstractFeedUpdater.py	Wed Aug 24 10:53:46 2011 +0200
@@ -0,0 +1,54 @@
+
+from datetime import datetime
+import feedparser
+import logging
+
+STATUS_ERROR = 400
+log = logging.getLogger("FeedUpdater")
+
+class AbstractFeedUpdater(object):
+    '''
+    Abstract base class for FeedUpdater implementations - handles all the parsing of the feed.
+    Subclasses need to implement creating and storing the new feed entries.
+    '''
+
+    def __init__(self, feed):
+        self.feed = feed
+
+    def update(self):
+        log.info("updating " + self.feed.rss_url)
+        result = self._retrieveFeed()
+        for entry in result.entries:
+            self._normalize(entry)
+            self._processEntry(entry)
+        self.feed.incrementNextUpdateDate()
+
+    def _retrieveFeed(self):
+        result = feedparser.parse(self.feed.rss_url)
+        # bozo flags if a feed is well-formed.
+#        if result["bozo"] > 0:
+#            raise FeedUpdateException()
+        status = result["status"]
+        if status >= STATUS_ERROR:
+            raise FeedUpdateException("HTTP status " + str(status))
+        return result
+
+    def _normalize(self, entry):
+        if not hasattr(entry, "id"):
+            entry.id = entry.link
+        if not hasattr(entry, "updated_parsed"):
+            entry.updated_parsed = datetime.today()
+        else:
+            entry.updated_parsed = datetime(*entry.updated_parsed[:6])
+        if not hasattr(entry, "summary"):
+            if hasattr(entry, "content"):
+                entry.summary = entry.content[0].value
+            else:
+                entry.summary = ""
+
+    def _processEntry(self, entry):
+        raise Exception("_processEntry is abstract, subclasses must override")
+
+
+class FeedUpdateException(Exception):
+    pass