From f1a87e5496367b91bdcd2f8bc356bd9bfb6d80c9 Mon Sep 17 00:00:00 2001
From: Stacy Brock <brock@oregonstate.edu>
Date: Wed, 14 Apr 2021 14:37:26 -0700
Subject: [PATCH] Add 4hr cache for filtered messages; add log helper func

---
 mail-filter.py | 41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/mail-filter.py b/mail-filter.py
index 7d415ef..123554c 100644
--- a/mail-filter.py
+++ b/mail-filter.py
@@ -45,6 +45,11 @@ handler = logging.handlers.TimedRotatingFileHandler(
 handler.setFormatter(formatter)
 logger.addHandler(handler)
 
+# helper function for logging
+def log(msg, level=logging.INFO):
+    print(msg)
+    logger.log(level, msg)
+
 
 class O365MailFilter(object):
     _scopes = [
@@ -56,7 +61,10 @@ class O365MailFilter(object):
         self._config = config
         self._is_canceled = False
         self._folders = {}
-        self._normalized = {}
+        self._filtered_cache = {
+            'last_reset': None,
+            'ids': set()
+        }
 
         # auth with O365
         self._authenticate()
@@ -74,13 +82,13 @@ class O365MailFilter(object):
         if not self._account.is_authenticated:
             self._account.authenticate(scopes=self._scopes)
 
-        logger.info('Authentication successful')
+        log('Authentication successful')
 
     def _load_filters(self):
         """ load filter code from a file on disk """
         loader = SourceFileLoader('filters', self._config['FILTERS_FILE'])
         module = loader.load_module()
-        module.normalize_lists(self)
+        module.init_filters(self)
         # make 'filter_message()' implemented in the file available for use
         # within this class as 'self._filter_message()'
         self._filter_message = module.filter_message
@@ -95,17 +103,25 @@ class O365MailFilter(object):
         for folder in folders:
             self._folders[folder.name] = folder.folder_id
 
+    def _clear_cache(self):
+        """ clear the filtered message cache """
+        log('Clearing filtered message cache...', logging.DEBUG)
+        self._filtered_cache = {
+            'last_reset': pendulum.now(),
+            'ids': set()
+        }
+
     def _repr_message(self, message):
         """ returns a str representation of a message suitable for logging """
         # to = ','.join([r.address for r in message.to])
         return f"[FROM: {message.sender.address} SUBJ: {message.subject}]"
 
     def _log_result(self, message, result):
-        logger.info(f"{self._repr_message(message)} RESULT: {result}")
+        log(f"{self._repr_message(message)} RESULT: {result}")
 
     def filter(self):
-        self._load_filters()
         self._load_folders()
+        self._load_filters()
 
         mailbox = self._account.mailbox()
         inbox = mailbox.inbox_folder()
@@ -122,26 +138,35 @@ class O365MailFilter(object):
         messages = inbox.get_messages(query=query, limit=limit, batch=25)
 
         for message in messages:
+            if message.object_id in self._filtered_cache['ids']:
+                # we've already filtered this message, so skip it
+                continue
             self._filter_message(self, message)
+            self._filtered_cache['ids'].add(message.object_id)
 
     def run(self):
         """ run filter as a loop """
         while not self._is_canceled:
+            # clear the filtered message cache if it's older than 4 hours
+            if (self._filtered_cache['last_reset'] is None or
+                    self._filtered_cache['last_reset'] < pendulum.now().subtract(hours=4)):
+                self._clear_cache()
+
             self.filter()
             time.sleep(self._config['CHECK_INTERVAL'])
 
-        logger.info('Done.')
+        log('Done.')
 
     def exit(self):
         self._is_canceled = True
 
 
-logger.info('Initializing O365 mail filter...')
+log('Initializing O365 mail filter...')
 o365mf = O365MailFilter(config)
 
 def exit(signum, frame):
     """ signal handler for a clean exit """
-    logger.info(f"Caught signal {signum}, exiting...")
+    log(f"Caught signal {signum}, exiting...")
     o365mf.exit()
 
 if __name__ == '__main__':