Add file_id codec

pyrogram/client/utils.py

@@ -1,3 +1,5 @@
+from base64 import b64encode, b64decode
+
 import pyrogram
 from pyrogram.api import types
 
@@ -163,3 +165,39 @@ def parse_message_service(message: types.MessageService, users: dict, chats: dic
         migrate_from_chat_id=migrate_from_chat_id,
         group_chat_created=group_chat_created
     )
+
+
+def decode(s):
+    s = b64decode(s + "=" * (-len(s) % 4), "-_")
+    r = b""
+
+    assert s[-1] == 2
+
+    i = 0
+    while i < len(s) - 1:
+        if s[i] != 0:
+            r += bytes([s[i]])
+        else:
+            r += b"\x00" * s[i + 1]
+            i += 1
+
+        i += 1
+
+    return r
+
+
+def encode(s):
+    r = b""
+    n = 0
+
+    for i in s + bytes([2]):
+        if i == 0:
+            n += 1
+        else:
+            if n:
+                r += b"\x00" + bytes([n])
+                n = 0
+
+            r += bytes([i])
+
+    return b64encode(r, b"-_").decode().rstrip("=")