Sync: split _confirm() into two functions

One is responsible for sending the confirmation prompt while the other
waits for the reaction. The split allows for the confirmation prompt
to be edited with the results of automatic syncs too.

1 files changed, 32 insertions, 10 deletions

diff --git a/bot/cogs/sync/syncers.py b/bot/cogs/sync/syncers.py
index 2ba9a2a3a..2376a3f6f 100644
--- a/bot/cogs/sync/syncers.py
+++ b/bot/cogs/sync/syncers.py
@@ -21,6 +21,7 @@ _Diff = namedtuple('Diff', ('created', 'updated', 'deleted'))
 class Syncer(abc.ABC):
     """Base class for synchronising the database with objects in the Discord cache."""
 
+    _REACTION_EMOJIS = (constants.Emojis.check_mark, constants.Emojis.cross_mark)
     CONFIRM_TIMEOUT = 60 * 5  # 5 minutes
     MAX_DIFF = 10
 
@@ -33,17 +34,16 @@ class Syncer(abc.ABC):
         """The name of the syncer; used in output messages and logging."""
         raise NotImplementedError
 
-    async def _confirm(self, author: Member, message: t.Optional[Message] = None) -> bool:
+    async def _send_prompt(self, message: t.Optional[Message] = None) -> t.Optional[Message]:
         """
-        Send a prompt to confirm or abort a sync using reactions and return True if confirmed.
+        Send a prompt to confirm or abort a sync using reactions and return the sent message.
 
         If a message is given, it is edited to display the prompt and reactions. Otherwise, a new
-        message is sent to the dev-core channel and mentions the core developers role.
+        message is sent to the dev-core channel and mentions the core developers role. If the
+        channel cannot be retrieved, return None.
         """
         log.trace(f"Sending {self.name} sync confirmation prompt.")
 
-        allowed_emoji = (constants.Emojis.check_mark, constants.Emojis.cross_mark)
-        mention = ""
         msg_content = (
             f'Possible cache issue while syncing {self.name}s. '
             f'More than {self.MAX_DIFF} {self.name}s were changed. '
@@ -64,7 +64,7 @@ class Syncer(abc.ABC):
                         f"Failed to fetch channel for sending sync confirmation prompt; "
                         f"aborting {self.name} sync."
                     )
-                    return False
+                    return None
 
             mention = f"<@&{constants.Roles.core_developer}> "
             message = await channel.send(f"{mention}{msg_content}")
@@ -73,9 +73,19 @@ class Syncer(abc.ABC):
 
         # Add the initial reactions.
         log.trace(f"Adding reactions to {self.name} syncer confirmation prompt.")
-        for emoji in allowed_emoji:
+        for emoji in self._REACTION_EMOJIS:
             await message.add_reaction(emoji)
 
+        return message
+
+    async def _wait_for_confirmation(self, author: Member, message: Message) -> bool:
+        """
+        Wait for a confirmation reaction by `author` on `message` and return True if confirmed.
+
+        If `author` is a bot user, then anyone with the core developers role may react to confirm.
+        If there is no reaction within `CONFIRM_TIMEOUT` seconds, return False. To acknowledge the
+        reaction (or lack thereof), `message` will be edited.
+        """
         def check(_reaction, user):  # noqa: TYP
             # For automatic syncs, check for the core dev role instead of an exact author
             has_role = any(constants.Roles.core_developer == role.id for role in user.roles)
@@ -83,9 +93,15 @@ class Syncer(abc.ABC):
                 _reaction.message.id == message.id
                 and not user.bot
                 and has_role if author.bot else user == author
-                and str(_reaction.emoji) in allowed_emoji
+                and str(_reaction.emoji) in self._REACTION_EMOJIS
             )
 
+        # Preserve the core-dev role mention in the message edits so users aren't confused about
+        # where notifications came from.
+        mention = ""
+        if message.role_mentions:
+            mention = message.role_mentions[0].mention
+
         reaction = None
         try:
             log.trace(f"Waiting for a reaction to the {self.name} syncer confirmation prompt.")
@@ -137,8 +153,14 @@ class Syncer(abc.ABC):
         totals = {k: len(v) for k, v in diff._asdict().items() if v is not None}
 
         log.trace(f"Determining if confirmation prompt should be sent for {self.name} syncer.")
-        if sum(totals.values()) > self.MAX_DIFF and not await self._confirm(author, message):
-            return  # Sync aborted.
+        if sum(totals.values()) > self.MAX_DIFF:
+            message = await self._send_prompt(message)
+            if not message:
+                return  # Couldn't get channel.
+
+            confirmed = await self._wait_for_confirmation(author, message)
+            if not confirmed:
+                return  # Sync aborted.
 
         await self._sync(diff)