Implemented retrieval of alerts history

Tools/GardeningServer/alerts.py

Index: Tools/GardeningServer/alerts.py
diff --git a/Tools/GardeningServer/alerts.py b/Tools/GardeningServer/alerts.py
index 071dc7da47c6cf9f5e7f6756e47b44c06d733c75..05eb7be534765d872c393bacf521df1f8e050074 100644
--- a/Tools/GardeningServer/alerts.py
+++ b/Tools/GardeningServer/alerts.py
@@ -10,6 +10,8 @@ import webapp2
 import zlib
 
 from google.appengine.api import memcache
+from google.appengine.api import users
+from google.appengine.datastore import datastore_query
 from google.appengine.ext import ndb
 
 LOGGER = logging.getLogger(__name__)
@@ -24,12 +26,13 @@ class DateTimeEncoder(json.JSONEncoder):
 
 
 class AlertsJSON(ndb.Model):
+    type = ndb.StringProperty()
     json = ndb.BlobProperty(compressed=True)
     date = ndb.DateTimeProperty(auto_now_add=True)
 
 
 class AlertsHandler(webapp2.RequestHandler):
-    MEMCACHE_ALERTS_KEY = 'alerts'
+    ALERTS_TYPE = 'alerts'
 
     # Has no 'response' member.
     # pylint: disable=E1101
@@ -55,10 +58,11 @@ class AlertsHandler(webapp2.RequestHandler):
         self.send_json_data(uncompressed)
 
     def get(self):
-        self.get_from_memcache(AlertsHandler.MEMCACHE_ALERTS_KEY)
+        self.get_from_memcache(AlertsHandler.ALERTS_TYPE)
 
-    def save_alerts_to_history(self, alerts):
-        last_entry = AlertsJSON.query().order(-AlertsJSON.date).get()
+    def post_to_history(self, alerts_type, alerts):
+        last_query = AlertsJSON.query().filter(AlertsJSON.type == alerts_type)
+        last_entry = last_query.order(-AlertsJSON.date).get()
         last_alerts = json.loads(last_entry.json) if last_entry else {}
 
         # Only changes to the fields with 'alerts' in the name should cause a
@@ -71,7 +75,9 @@ class AlertsHandler(webapp2.RequestHandler):
             return filtered_json
 
         if alert_fields(last_alerts) != alert_fields(alerts):
-            new_entry = AlertsJSON(json=self.generate_json_dump(alerts))
+            new_entry = AlertsJSON(
+                json=self.generate_json_dump(alerts),
+                type=alerts_type)
             new_entry.put()
 
     # Has no 'response' member.
@@ -95,16 +101,57 @@ class AlertsHandler(webapp2.RequestHandler):
 
         return alerts
 
-    def update_alerts(self, memcache_key):
+    def update_alerts(self, alerts_type):
         alerts = self.parse_alerts(self.request.get('content'))
         if alerts:
-            self.post_to_memcache(memcache_key, alerts)
-            self.save_alerts_to_history(alerts)
+            self.post_to_memcache(alerts_type, alerts)
+            self.post_to_history(alerts_type, alerts)
 
     def post(self):
-        self.update_alerts(AlertsHandler.MEMCACHE_ALERTS_KEY)
+        self.update_alerts(AlertsHandler.ALERTS_TYPE)
+
+
+class AlertsHistory(webapp2.RequestHandler):
+    MAX_LIMIT_PER_PAGE = 50
+
+    def get(self):
+        alerts_query = AlertsJSON.query().order(-AlertsJSON.date)
+        result_json = {}
+
+        user = users.get_current_user()
+        if not user:
+            result_json['redirect-url'] = users.create_login_url(
+                self.request.uri)
+
+        # Return only public alerts for non-internal users.
+        if not user or not user.email().endswith('@google.com'):
+            alerts_query = alerts_query.filter(
+                AlertsJSON.type == AlertsHandler.ALERTS_TYPE)
+
+        cursor = self.request.get('cursor')
+        if cursor:
+            cursor = datastore_query.Cursor(urlsafe=cursor)
+
+        limit = int(self.request.get('limit', self.MAX_LIMIT_PER_PAGE))
+        limit = min(self.MAX_LIMIT_PER_PAGE, limit)
+
+        if cursor:
+            alerts, next_cursor, has_more = alerts_query.fetch_page(
+                limit, start_cursor=cursor)
+        else:
+            alerts, next_cursor, has_more = alerts_query.fetch_page(limit)
+
+        result_json.update({
+            'has_more': has_more,
+            'cursor': next_cursor.urlsafe() if next_cursor else '',
+            'history': [json.loads(alert.json) for alert in alerts]
+        })
+
+        self.response.headers['Content-Type'] = 'application/json'
+        self.response.out.write(json.dumps(result_json))
 
 
 app = webapp2.WSGIApplication([
-    ('/alerts', AlertsHandler)
+    ('/alerts', AlertsHandler),
+    ('/alerts-history', AlertsHistory)
 ])