From e2cb49669edd04bb73741fdabc10f206e97e71be Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Sat, 20 Jul 2019 12:46:59 -0300
Subject: [PATCH] dispatcher: add basics of subscription flags

---
 litecord/dispatcher.py        | 41 ++++++++++++++++++++++++++---------
 litecord/gateway/websocket.py | 24 ++++++++++++--------
 litecord/pubsub/dispatcher.py |  2 +-
 3 files changed, 47 insertions(+), 20 deletions(-)

diff --git a/litecord/dispatcher.py b/litecord/dispatcher.py
index 8d38303..29748a9 100644
--- a/litecord/dispatcher.py
+++ b/litecord/dispatcher.py
@@ -17,7 +17,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 """
 
-from typing import List, Any
+from typing import List, Any, Dict
 
 from logbook import Logger
 
@@ -57,7 +57,7 @@ class EventDispatcher:
             'lazy_guild': LazyGuildDispatcher(self),
         }
 
-    async def action(self, backend_str: str, action: str, key, identifier):
+    async def action(self, backend_str: str, action: str, key, identifier, *args):
         """Send an action regarding a key/identifier pair to a backend.
 
         Action is usually "sub" or "unsub".
@@ -69,13 +69,24 @@ class EventDispatcher:
         key = backend.KEY_TYPE(key)
         identifier = backend.VAL_TYPE(identifier)
 
-        return await method(key, identifier)
+        return await method(key, identifier, *args)
 
-    async def subscribe(self, backend: str, key: Any, identifier: Any):
+    async def subscribe(self, backend: str, key: Any, identifier: Any,
+                        flags: Dict[str, Any] = None):
         """Subscribe a single element to the given backend."""
+        flags = flags or {}
+
         log.debug('SUB backend={} key={} <= id={}',
                   backend, key, identifier, backend)
 
+        # this is a hacky solution for backwards compatibility between backends
+        # that implement flags and backends that don't.
+
+        # passing flags to backends that don't implement flags will
+        # cause errors as expected.
+        if flags:
+            return await self.action(backend, 'sub', key, identifier, flags)
+
         return await self.action(backend, 'sub', key, identifier)
 
     async def unsubscribe(self, backend: str, key: Any, identifier: Any):
@@ -93,24 +104,34 @@ class EventDispatcher:
         """Alias to unsubscribe()."""
         return await self.unsubscribe(backend, key, identifier)
 
-    async def sub_many(self, backend_str: str, identifier: Any, keys: list):
+    async def sub_many(self, backend_str: str, identifier: Any,
+                       keys: list, flags: Dict[str, Any] = None):
         """Subscribe to multiple channels (all in a single backend)
         at a time.
 
         Usually used when connecting to the gateway and the client
         needs to subscribe to all their guids.
         """
+        flags = flags or {}
         for key in keys:
-            await self.subscribe(backend_str, key, identifier)
+            await self.subscribe(backend_str, key, identifier, flags)
 
     async def mass_sub(self, identifier: Any,
                        backends: List[tuple]):
         """Mass subscribe to many backends at once."""
-        for backend_str, keys in backends:
-            log.debug('subscribing {} to {} keys in backend {}',
-                      identifier, len(keys), backend_str)
+        for bcall in backends:
+            backend_str, keys = bcall[0], bcall[1]
 
-            await self.sub_many(backend_str, identifier, keys)
+            if len(bcall) == 2:
+                flags = {}
+            elif len(bcall == 3):
+                # we have flags
+                flags = bcall[2]
+
+            log.debug('subscribing {} to {} keys in backend {}, flags: {}',
+                      identifier, len(keys), backend_str, flags)
+
+            await self.sub_many(backend_str, identifier, keys, flags)
 
     async def dispatch(self, backend_str: str, key: Any, *args, **kwargs):
         """Dispatch an event to the backend.
diff --git a/litecord/gateway/websocket.py b/litecord/gateway/websocket.py
index af660f2..d68f2d6 100644
--- a/litecord/gateway/websocket.py
+++ b/litecord/gateway/websocket.py
@@ -437,17 +437,23 @@ class GatewayWebsocket:
         # fetch all group dms the user is a member of.
         gdm_ids = await self.user_storage.get_gdms_internal(user_id)
 
-        log.info('subscribing to {} guilds', len(guild_ids))
-        log.info('subscribing to {} dms', len(dm_ids))
-        log.info('subscribing to {} group dms', len(gdm_ids))
+        log.info('subscribing to {} guilds {} dms {} gdms',
+                 len(guild_ids), len(dm_ids), len(gdm_ids))
 
-        # TODO(gw-guild-subscriptions)
-        #  make a channel:typing and guild:presence subchannels
-        await self.ext.dispatcher.mass_sub(user_id, [
-            ('guild', guild_ids),
+        # guild_subscriptions:
+        #  enables dispatching of guild subscription events
+        #  (presence and typing events)
+
+        # we enable processing of guild_subscriptions by adding flags
+        # when subscribing to the given backend. those are optional.
+        channels_to_sub = [
+            ('guild', guild_ids,
+             {'presence': guild_subscriptions, 'typing': guild_subscriptions}),
             ('channel', dm_ids),
-            ('channel', gdm_ids)
-        ])
+            ('channel', gdm_ids),
+        ]
+
+        await self.ext.dispatcher.mass_sub(user_id, channels_to_sub)
 
         if not self.state.bot:
             # subscribe to all friends
diff --git a/litecord/pubsub/dispatcher.py b/litecord/pubsub/dispatcher.py
index dd03ef2..4ad5ee7 100644
--- a/litecord/pubsub/dispatcher.py
+++ b/litecord/pubsub/dispatcher.py
@@ -89,7 +89,7 @@ class Dispatcher:
             try:
                 await state.ws.dispatch(event, data)
                 res.append(state.session_id)
-            except:
+            except Exception:
                 log.exception('error while dispatching')
 
         return res