From 6f4faf7a580c554c7d50267734f7a875e49267fb Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Sat, 19 Dec 2020 12:48:08 +0200
Subject: [PATCH] Store Matrix redaction state and ignore deletions of redacted
 messages

---
 ..._add_matrix_redaction_state_to_message_.py | 25 +++++++++++++++++++
 mautrix_telegram/abstract_user.py             |  4 +++
 mautrix_telegram/db/message.py                |  4 ++-
 mautrix_telegram/portal/matrix.py             | 14 ++++++++---
 4 files changed, 42 insertions(+), 5 deletions(-)
 create mode 100644 alembic/versions/7de69cf5809e_add_matrix_redaction_state_to_message_.py

diff --git a/alembic/versions/7de69cf5809e_add_matrix_redaction_state_to_message_.py b/alembic/versions/7de69cf5809e_add_matrix_redaction_state_to_message_.py
new file mode 100644
index 00000000..15d2ecb0
--- /dev/null
+++ b/alembic/versions/7de69cf5809e_add_matrix_redaction_state_to_message_.py
@@ -0,0 +1,25 @@
+"""Add Matrix redaction state to message table
+
+Revision ID: 7de69cf5809e
+Revises: 888275d58e57
+Create Date: 2020-12-19 12:39:57.368568
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '7de69cf5809e'
+down_revision = '888275d58e57'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    with op.batch_alter_table('message', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('redacted', sa.Boolean(), server_default=sa.false(), nullable=True))
+
+
+def downgrade():
+    with op.batch_alter_table('message', schema=None) as batch_op:
+        batch_op.drop_column('redacted')
diff --git a/mautrix_telegram/abstract_user.py b/mautrix_telegram/abstract_user.py
index 7d8a3e32..dbe71487 100644
--- a/mautrix_telegram/abstract_user.py
+++ b/mautrix_telegram/abstract_user.py
@@ -420,6 +420,8 @@ class AbstractUser(ABC):
 
         for message_id in update.messages:
             for message in DBMessage.get_all_by_tgid(TelegramID(message_id), self.tgid):
+                if message.redacted:
+                    continue
                 message.delete()
                 number_left = DBMessage.count_spaces_by_mxid(message.mxid, message.mx_room)
                 if number_left == 0:
@@ -433,6 +435,8 @@ class AbstractUser(ABC):
 
         for message_id in update.messages:
             for message in DBMessage.get_all_by_tgid(TelegramID(message_id), channel_id):
+                if message.redacted:
+                    continue
                 message.delete()
                 await self._try_redact(message)
 
diff --git a/mautrix_telegram/db/message.py b/mautrix_telegram/db/message.py
index e39f2a72..a765650a 100644
--- a/mautrix_telegram/db/message.py
+++ b/mautrix_telegram/db/message.py
@@ -15,7 +15,8 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 from typing import Optional, Iterator, List
 
-from sqlalchemy import Column, UniqueConstraint, Integer, String, and_, func, desc, select
+from sqlalchemy import (Column, UniqueConstraint, Integer, String, Boolean, and_, func, desc,
+                        select, false)
 
 from mautrix.types import RoomID, EventID
 from mautrix.util.db import Base
@@ -31,6 +32,7 @@ class Message(Base):
     tgid: TelegramID = Column(Integer, primary_key=True)
     tg_space: TelegramID = Column(Integer, primary_key=True)
     edit_index: int = Column(Integer, primary_key=True)
+    redacted: bool = Column(Boolean, server_default=false())
 
     __table_args__ = (UniqueConstraint("mxid", "mx_room", "tg_space", name="_mx_id_room_2"),)
 
diff --git a/mautrix_telegram/portal/matrix.py b/mautrix_telegram/portal/matrix.py
index 2bdccafb..e1276454 100644
--- a/mautrix_telegram/portal/matrix.py
+++ b/mautrix_telegram/portal/matrix.py
@@ -435,12 +435,18 @@ class PortalMatrix(BasePortal, ABC):
         space = self.tgid if self.peer_type == "channel" else real_deleter.tgid
         message = DBMessage.get_by_mxid(event_id, self.mxid, space)
         if not message:
-            return
-        if message.edit_index == 0:
+            self.log.trace(f"Ignoring Matrix redaction of unknown event {event_id}")
+        elif message.redacted:
+            self.log.debug("Ignoring Matrix redaction of already redacted event "
+                           f"{message.mxid} in {message.mx_room}")
+        elif message.edit_index != 0:
+            message.edit(redacted=True)
+            self.log.debug("Ignoring Matrix redaction of edit event "
+                           f"{message.mxid} in {message.mx_room}")
+        else:
+            message.edit(redacted=True)
             await real_deleter.client.delete_messages(self.peer, [message.tgid])
             await self._send_delivery_receipt(redaction_event_id)
-        else:
-            self.log.debug(f"Ignoring deletion of edit event {message.mxid} in {message.mx_room}")
 
     async def _update_telegram_power_level(self, sender: 'u.User', user_id: TelegramID,
                                            level: int) -> None: