implemented offline caching

decal

@@ -62,6 +62,9 @@ parser.add_argument("-n",
                     action="store",
                     type=int,
                     help="show n months")
+parser.add_argument("-s","--sync",
+                    action="store_true",
+                    help="sync the calendar cache")
 
 args = vars(parser.parse_args())
 
@@ -74,7 +77,10 @@ if args["create"]:
 if not os.path.exists(configpath):
     config['DEFAULT'] = {'uri': 'your caldav server here',
                          'user': 'your username here',
-                         'password': 'your pass here'}
+                         'password': 'your pass here',
+                         'cache':os.env['HOME']+'/.cache/decal.json',
+                         'cacheEnabled':1,
+                         'syncAfter':1}
     print("Creating an empty config in ~/.config/decal.conf")
     with open(configpath,'w') as configfile:
         config.write(configfile)
@@ -189,13 +195,6 @@ else:
     start,end = getbounds(args["year"],args["month"],1)
     offset = 1
 
-# connect to the DAV and receive calendars
-client = caldav.DAVClient(url = config['DEFAULT']['uri'],
-                          username = config['DEFAULT']['user'],
-                          password = config['DEFAULT']['password'])
-principal = client.principal()
-calendars = principal.calendars()
-
 # aggregate selected calendars
 def aggregateCalendars(calendars):
     calendars2 = []
@@ -205,10 +204,6 @@ def aggregateCalendars(calendars):
             calendars2.append(cal)
     return calendars2
 
-if "calendars" in config['DEFAULT']:
-    calendars = aggregateCalendars(calendars)
-
-
 def daysOfEvent(event):
     event = event.vobject_instance.vevent.contents
     curdate = event["dtstart"][0].value
@@ -234,7 +229,6 @@ def jsonifyEvent(event):
             evdata[key] = event[key][0].value
     return evdata
 
-
 def generateDateTree(calendars):
     events = {}
     for cal in calendars:
@@ -246,10 +240,42 @@ def generateDateTree(calendars):
                 events[date].append(jsonifyEvent(event))
     return events
 
-events = generateDateTree(calendars)
+cache = None
+if "cache" in config['DEFAULT']:
+    if os.path.exists(config['DEFAULT']['cache']):
+        with open(config['DEFAULT']['cache'],"r") as file:
+            cache = json.loads(file.read())
+
+def updateCriteria():
+    if not ("cacheEnabled" in config["DEFAULT"]):
+        return False
+    if (not (config['DEFAULT']["cacheEnabled"] == "1")):
+        return False
+    if not cache:
+        return True
+    date = datetime.datetime.strptime(cache["lastsync"],"%Y-%m-%d")
+    if args["sync"]:
+        return True
+    return (date.date() <= today - timedelta(days=int(config['DEFAULT']["syncAfter"])))
+
+#Update cache if update criteria are met.
+if updateCriteria():
+    # connect to the DAV and receive calendars
+    client = caldav.DAVClient(url = config['DEFAULT']['uri'],
+                              username = config['DEFAULT']['user'],
+                              password = config['DEFAULT']['password'])
+    principal = client.principal()
+    calendars = principal.calendars()
+    if "calendars" in config['DEFAULT']:
+        calendars = aggregateCalendars(calendars)
+    cache = generateDateTree(calendars)
+    cache["lastsync"] = str(today)
+    with open(config['DEFAULT']['cache'],"w") as file:
+        file.write(json.dumps(cache))
+events = cache
 
 if args["json"]:
-    print(json.JSONEncoder().encode(events))
+    print(json.dumps(events))
     exit(0)
 
 # and now we're just generating calendar lines