fix(contrib): handle matrix media placeholder captions (#572)

Recognize bridge-generated media captions like "Alice sent an image" so bridge messages keep the real sender and drop the duplicated placeholder caption.

Also make the shared sender helper return the sender id for forwarded messages and stop guessing captionless media senders from recent cache.

Reference: https://t.me/ArchlinuxCN_Appearance/294784

Author: LuciusChen

contrib/telega-bridge-bot.el

@@ -314,8 +314,15 @@ If FORCE-UPDATE is non-nil, force update the file."
 
 (defun telega-bridge-bot--matrix-file-spliter (text)
   "Split TEXT into username and message."
-  ;; Split with file type prefix
-  (split-string text " sent \\(a file\\|an image\\|a video\\): "))
+  (when (string-match
+         "\\`\\(.+?\\) sent \\(a file\\|an image\\|a video\\)\\(?:: \\(.*\\)\\)?\\'"
+         text)
+    (list
+     (match-string 1 text)
+     ;; Keep empty string for bridge-generated placeholder captions like
+     ;; \"Alice sent an image\" so caller can still replace sender and
+     ;; clear the duplicated caption.
+     (or (match-string 3 text) ""))))
 
 
 ;;; bridge
@@ -378,6 +385,23 @@ Return a string if STRING is non-nil."
   "Return cached bridge username for CHAT-ID and BOT-ID."
   (gethash (list chat-id bot-id) telega-bridge-bot--recent-counterparty-name))
 
+(defun telega-bridge-bot--set-msg-sender (msg sender-id)
+  "Set MSG sender to SENDER-ID."
+  (plist-put msg :sender_id (list :@type "messageSenderUser" :user_id sender-id)))
+
+(defun telega-bridge-bot--cached-msg-sender-name (msg chat-id bot-id)
+  "Return bridge sender name for MSG using signature or recent cache."
+  (or (telega-tl-str msg :author_signature)
+      (telega-bridge-bot--cached-counterparty-name chat-id bot-id)))
+
+(defun telega-bridge-bot--apply-bridge-sender (msg chat-id bot-id username)
+  "Apply bridge sender USERNAME to MSG in CHAT-ID from BOT-ID."
+  (let ((sender-id
+         (telega-bridge-bot--update-user-info
+          (telega--tl-get msg :id) chat-id bot-id username)))
+    (telega-bridge-bot--set-msg-sender msg sender-id)
+    sender-id))
+
 (defun telega-bridge-bot--file-id (path)
   "Return file id based on PATH and modification time seconds."
   (let* ((mtime (file-attribute-modification-time (file-attributes path)))
@@ -463,16 +487,13 @@ If FORCE-UPDATE is non-nil, force update the user info."
 
 (defun telega-bridge-bot--update-sticker (msg)
   "Update sender id in sticker MSG using recently resolved bridge username."
-  (when-let* ((msg-id (telega--tl-get msg :id))
-              (chat-id (telega--tl-get msg :chat_id))
+  (when-let* ((chat-id (telega--tl-get msg :chat_id))
               (bot-id (telega--tl-get (telega-msg-sender msg) :id))
               (counterparty-info (telega-bridge-bot--counterparty-info chat-id bot-id))
               (content (telega--tl-get msg :content))
               (sticker-p (eq (telega--tl-type content) 'messageSticker))
-              (name (or (telega-tl-str msg :author_signature)
-                        (telega-bridge-bot--cached-counterparty-name chat-id bot-id))))
-    (let ((sender-id (telega-bridge-bot--update-user-info msg-id chat-id bot-id name)))
-      (plist-put msg :sender_id (list :@type "messageSenderUser" :user_id sender-id)))))
+              (name (telega-bridge-bot--cached-msg-sender-name msg chat-id bot-id)))
+    (telega-bridge-bot--apply-bridge-sender msg chat-id bot-id name)))
 
 (defun telega-bridge-bot--download-async-callback (chat-id msg-id)
   "Callback for `telega-bridge-bot--download-async'.
@@ -487,8 +508,7 @@ Will update CHAT-ID MSG-ID when download completed."
 
 (defun telega-bridge-bot--update-fmt-text (msg)
   "Update sender id and remove duplicated username in MSG."
-  (when-let* ((msg-id (telega--tl-get msg :id))
-              (chat-id (telega--tl-get msg :chat_id))
+  (when-let* ((chat-id (telega--tl-get msg :chat_id))
               (bot-id (telega--tl-get (telega-msg-sender msg) :id))
               (counterparty-info (telega-bridge-bot--counterparty-info chat-id bot-id)) ; check if it is a bridge bot
               (counterparty-type (plist-get counterparty-info :type))
@@ -503,44 +523,43 @@ Will update CHAT-ID MSG-ID when download completed."
               (name-and-body (funcall spliter content-text-text))
               (name (car name-and-body))
               (body (cadr name-and-body))) ; skip if no body
-    (let ((sender-id (telega-bridge-bot--update-user-info msg-id chat-id bot-id name)))
-      ;; replace sender
-      (plist-put msg :sender_id (list :@type "messageSenderUser" :user_id sender-id))
-      ;; remove duplicated username in body
-      ;; we don't use body directly here
-      ;; because then we only need to make sure the name is correct
-      ;; makes it easier to write the split function
-      (plist-put
-       content :text
-       (telega-bridge-bot--remove-username content-text body)))))
+    (let ((sender-id
+           (telega-bridge-bot--apply-bridge-sender msg chat-id bot-id name)))
+      (prog1 sender-id
+        ;; remove duplicated username in body
+        ;; we don't use body directly here
+        ;; because then we only need to make sure the name is correct
+        ;; makes it easier to write the split function
+        (plist-put
+         content :text
+         (telega-bridge-bot--remove-username content-text body))))))
 
 (defun telega-bridge-bot--update-file (msg)
   "Update sender id and remove file caption in MSG."
-  (when-let* ((msg-id (telega--tl-get msg :id))
-              (chat-id (telega--tl-get msg :chat_id))
+  (when-let* ((chat-id (telega--tl-get msg :chat_id))
               (bot-id (telega--tl-get (telega-msg-sender msg) :id))
               (counterparty-info (telega-bridge-bot--counterparty-info chat-id bot-id)) ; check if it is a bridge bot
               (counterparty-type (plist-get counterparty-info :type))
-              (content (telega--tl-get msg :content))
-              (content-caption (telega--tl-get content :caption))
-              (fmt-text-p (eq (telega--tl-type content-caption) 'formattedText))
-              (content-caption-text (telega--tl-get content-caption :text)) ; get the msg text
-              (spliter (telega--tl-get
-                        telega-bridge-bot--counterparty-handler-plist
-                        counterparty-type :file-spliter))
-              (name-and-body (funcall spliter content-caption-text))
-              (name (car name-and-body))
-              (body (cadr name-and-body))) ; skip if no body
-    (let ((sender-id (telega-bridge-bot--update-user-info msg-id chat-id bot-id name)))
-      ;; replace sender
-      (plist-put msg :sender_id (list :@type "messageSenderUser" :user_id sender-id))
-      ;; remove caption
-      (plist-put content :caption nil))))
+              (content (telega--tl-get msg :content)))
+    (let* ((content-caption (telega--tl-get content :caption))
+           (content-caption-text (telega--tl-get content-caption :text))
+           (spliter (telega--tl-get
+                     telega-bridge-bot--counterparty-handler-plist
+                     counterparty-type :file-spliter))
+           (name-and-body (and content-caption-text
+                               (funcall spliter content-caption-text)))
+           (name (car-safe name-and-body)))
+      (when name
+        (let ((sender-id
+               (telega-bridge-bot--apply-bridge-sender
+                msg chat-id bot-id name)))
+          (prog1 sender-id
+            ;; remove bridge-generated caption when sender came from caption
+            (plist-put content :caption nil)))))))
 
 (defun telega-bridge-bot--update-forwarded (msg)
   "Update forwarded sender id and remove duplicated username in MSG."
-  (when-let* ((msg-id (telega--tl-get msg :id))
-              (forward-info (telega--tl-get msg :forward_info))
+  (when-let* ((forward-info (telega--tl-get msg :forward_info))
               (fwd-info-p (eq (telega--tl-type forward-info) 'messageForwardInfo))
               (bot-id (telega--tl-get forward-info :origin :sender_user_id))
               (chat-id (telega--tl-get forward-info :from_chat_id))
@@ -556,13 +575,16 @@ Will update CHAT-ID MSG-ID when download completed."
               (name-and-body (funcall spliter content-text-text))
               (name (car name-and-body))
               (body (cadr name-and-body))) ; skip if no body
-    (let ((sender-id (telega-bridge-bot--update-user-info msg-id chat-id bot-id name)))
-      ;; replace sender
-      (plist-put forward-info :origin (list :@type "messageOriginUser" :sender_user_id sender-id))
-      ;; remove duplicated username in body
-      (plist-put
-       content :text
-       (telega-bridge-bot--remove-username content-text body)))))
+    (let ((sender-id
+           (telega-bridge-bot--apply-bridge-sender msg chat-id bot-id name)))
+      (prog1 sender-id
+        ;; replace sender
+        (plist-put forward-info :origin
+                   (list :@type "messageOriginUser" :sender_user_id sender-id))
+        ;; remove duplicated username in body
+        (plist-put
+         content :text
+         (telega-bridge-bot--remove-username content-text body))))))
 
 (defun telega-bridge-bot--update-msg (msg &rest _)
   "Replace the sender in MSG with the other party's sender."