Handle surrogates in a non-hacky way

mautrix_telegram/formatter/util.py

@@ -0,0 +1,16 @@
+# Unicode surrogate handling
+# From https://github.com/LonamiWebs/Telethon/blob/master/telethon/extensions/markdown.py
+import struct
+
+
+def add_surrogates(text):
+    if text is None:
+        return None
+    return "".join("".join(chr(y) for y in struct.unpack("<HH", x.encode("utf-16-le")))
+                   if (0x10000 <= ord(x) <= 0x10FFFF) else x for x in text)
+
+
+def remove_surrogates(text):
+    if text is None:
+        return None
+    return text.encode("utf-16", "surrogatepass").decode("utf-16")