User correct Matrix accounts when redacting events

changelog.d/766.bugfix

@@ -0,0 +1 @@
+User correct Matrix accounts when redacting events.

src/BaseSlackHandler.ts

@@ -50,6 +50,7 @@ export interface ISlackEventMessageAttachment {
 }
 
 export interface ISlackMessageEvent extends ISlackEvent {
+    team?: string;
     team_domain?: string;
     team_id?: string;
     user?: string;

src/SlackEventHandler.ts

@@ -18,6 +18,7 @@ import { BaseSlackHandler, ISlackEvent, ISlackMessageEvent, ISlackUser } from ".
 import { BridgedRoom } from "./BridgedRoom";
 import { Main, METRIC_RECEIVED_MESSAGE } from "./Main";
 import { Logger } from "matrix-appservice-bridge";
+import { TeamEntry } from "./datastore/Models";
 const log = new Logger("SlackEventHandler");
 
 /**
@@ -289,11 +290,10 @@ export class SlackEventHandler extends BaseSlackHandler {
                 }
             }
         } else if (msg.subtype === "message_deleted" && msg.deleted_ts) {
-            const originalEvent = await this.main.datastore.getEventBySlackId(msg.channel, msg.deleted_ts);
-            if (originalEvent) {
-                const botClient = this.main.botIntent.matrixClient;
-                await botClient.redactEvent(originalEvent.roomId, originalEvent.eventId);
-                return;
+            try {
+                await this.deleteMessage(msg, team);
+            } catch (err) {
+                log.error(err);
             }
             // If we don't have the event
             throw Error("unknown_message");
@@ -315,6 +315,42 @@ export class SlackEventHandler extends BaseSlackHandler {
         return room.onSlackMessage(msg);
     }
 
+    private async deleteMessage(msg: ISlackMessageEvent, team: TeamEntry): Promise<void> {
+        const originalEvent = await this.main.datastore.getEventBySlackId(msg.channel, msg.deleted_ts!);
+        if (originalEvent) {
+            const previousMessage = msg.previous_message;
+            if (!previousMessage) {
+                throw new Error(`Cannot delete message with no previous_message: ${JSON.stringify(msg)}`);
+            }
+
+            // Try to determine the Matrix user responsible for deleting the message, fallback to our main bot if all else fails
+            if (!previousMessage.user) {
+                log.warn("We don't know the original sender of", previousMessage, "will try to remove with our bot");
+            }
+
+            const isOurMessage = previousMessage.subtype === 'bot_message' && (previousMessage.bot_id === team.bot_id);
+
+            if (previousMessage.user && !isOurMessage) {
+                try {
+                    const ghost = await this.main.ghostStore.get(previousMessage.user, previousMessage.team_domain, previousMessage.team);
+                    await ghost.redactEvent(originalEvent.roomId, originalEvent.eventId);
+                    return;
+                } catch (err) {
+                    log.warn(`Failed to remove message on behalf of ${previousMessage.user}, falling back to our bot`);
+                }
+            }
+
+            try {
+                const botClient = this.main.botIntent.matrixClient;
+                await botClient.redactEvent(originalEvent.roomId, originalEvent.eventId, "Deleted on Slack");
+            } catch (err) {
+                throw new Error(
+                    `Failed to remove message ${JSON.stringify(previousMessage)} with our Matrix bot. insufficient power level? Error: ${err}`
+                );
+            }
+        }
+    }
+
     private async handleReaction(event: ISlackEventReaction, teamId: string) {
         // Reactions store the channel in the item
         const channel = event.item.channel;

src/SlackGhost.ts

@@ -321,6 +321,13 @@ export class SlackGhost {
         return Slackdown.parse(body);
     }
 
+    public async redactEvent(roomId: string, eventId: string) {
+        if (!this._intent) {
+            throw Error('No intent associated with ghost');
+        }
+        await this._intent.matrixClient.redactEvent(roomId, eventId);
+    }
+
     public async sendInThread(roomId: string, text: string, slackRoomId: string,
         slackEventTs: string, replyEvent: IMatrixReplyEvent): Promise<void> {
         const content = {