Linkify typed usernames/id in markdown

src/backend/html_markdown.py

@@ -3,6 +3,8 @@
 """HTML and Markdown processing tools."""
 
 import re
+from typing import Dict, Optional
+from urllib.parse import quote
 
 import html_sanitizer.sanitizer as sanitizer
 import mistune
@@ -162,13 +164,33 @@ class HTMLProcessor:
 
 
     def from_markdown(
-        self, text: str, inline: bool = False, outgoing: bool = False,
+        self,
+        text:              str,
+        inline:            bool                     = False,
+        outgoing:          bool                     = False,
+        mentionable_users: Optional[Dict[str, str]] = None,
     ) -> str:
         """Return filtered HTML from Markdown text."""
 
+        if mentionable_users:
+            text = self.markdown_linkify_users(text, mentionable_users)
+
         return self.filter(self._markdown_to_html(text), inline, outgoing)
 
 
+    def markdown_linkify_users(self, text: str, users: Dict[str, str]) -> str:
+        print(text)
+
+        for user_id, username in users.items():
+            repl = rf"\1[{user_id}](https://matrix.to/#/{quote(user_id)})\2"
+            text = re.sub(rf"(^|\W){user_id}($|\W)", repl, text)
+
+            repl = rf"\1[{username}](https://matrix.to/#/{quote(user_id)})\2"
+            text = re.sub(rf"(^|\W){username}($|\W)", repl, text)
+
+        return text
+
+
     def filter(
         self, html: str, inline: bool = False, outgoing: bool = False,
     ) -> str:

src/backend/matrix_client.py

@@ -308,6 +308,15 @@ class MatrixClient(nio.AsyncClient):
     async def send_text(self, room_id: str, text: str) -> None:
         """Send a markdown `m.text` or `m.notice` (with `/me`) message ."""
 
+        from_md = partial(
+            HTML.from_markdown,
+            mentionable_users={
+                user_id: member.display_name or user_id
+                for user_id, member in
+                self.models[self.user_id, room_id, "members"].items()
+            },
+        )
+
         escape = False
         if text.startswith("//") or text.startswith(r"\/"):
             escape = True
@@ -317,13 +326,13 @@ class MatrixClient(nio.AsyncClient):
             event_type = nio.RoomMessageEmote
             text       = text[len("/me "): ]
             content    = {"body": text, "msgtype": "m.emote"}
-            to_html    = HTML.from_markdown(text, inline=True, outgoing=True)
-            echo_body  = HTML.from_markdown(text, inline=True)
+            to_html    = from_md(text, inline=True, outgoing=True)
+            echo_body  = from_md(text, inline=True)
         else:
             event_type = nio.RoomMessageText
             content    = {"body": text, "msgtype": "m.text"}
-            to_html    = HTML.from_markdown(text, outgoing=True)
-            echo_body  = HTML.from_markdown(text)
+            to_html    = from_md(text, outgoing=True)
+            echo_body  = from_md(text)
 
         if to_html not in (html.escape(text), f"<p>{html.escape(text)}</p>"):
             content["format"]         = "org.matrix.custom.html"