From b2018d9ae94f8f688b07684537b00903f09b49fe Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Fri, 11 Jun 2021 11:04:22 +0300
Subject: [PATCH] Decrypt events in get_event. Fixes #123

---
 maubot/matrix.py | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/maubot/matrix.py b/maubot/matrix.py
index 756ec95..f93b80d 100644
--- a/maubot/matrix.py
+++ b/maubot/matrix.py
@@ -23,7 +23,8 @@ from mautrix.client import Client as MatrixClient, SyncStream
 from mautrix.util.formatter import MatrixParser, MarkdownString, EntityType
 from mautrix.util import markdown
 from mautrix.types import (EventType, MessageEvent, Event, EventID, RoomID, MessageEventContent,
-                           MessageType, TextMessageEventContent, Format, RelatesTo)
+                           MessageType, TextMessageEventContent, Format, RelatesTo, EncryptedEvent)
+from mautrix.errors import DecryptionError
 
 
 class HumanReadableString(MarkdownString):
@@ -132,10 +133,19 @@ class MaubotMatrixClient(MatrixClient):
         return super().dispatch_event(event, source)
 
     async def get_event(self, room_id: RoomID, event_id: EventID) -> Event:
-        event = await super().get_event(room_id, event_id)
-        if isinstance(event, MessageEvent):
-            event.content.trim_reply_fallback()
-            return MaubotMessageEvent(event, self)
+        evt = await super().get_event(room_id, event_id)
+        if isinstance(evt, EncryptedEvent) and self.crypto:
+            try:
+                self.crypto_log.trace(f"get_event: Decrypting {evt.event_id} in {evt.room_id}...")
+                decrypted = await self.crypto.decrypt_megolm_event(evt)
+            except DecryptionError as e:
+                self.crypto_log.warning(f"get_event: Failed to decrypt {evt.event_id}: {e}")
+                return
+            self.crypto_log.trace(f"get_event: Decrypted {evt.event_id}: {decrypted}")
+            evt = decrypted
+        if isinstance(evt, MessageEvent):
+            evt.content.trim_reply_fallback()
+            return MaubotMessageEvent(evt, self)
         else:
-            event.client = self
-        return event
+            evt.client = self
+        return evt