Added get_url() method for Message object and shifted_id property for Chat object (#585)

* Added get_url() method for Message object and shifted_id property for Chat object

* Added missing closing bracket to shifted_id description

* Added basic groups to skipped pattern, simplified code

* Return None instead of raising TypeError, removed redundant f-string

* Change get_url typing to Optional[str]

* Better shifted_id method

* get_url tests added

* Added whitespace (E226)

* Code format with black

* Parametrized test

aiogram/types/chat.py

@@ -54,3 +54,19 @@ class Chat(TelegramObject):
     """*Optional*. Unique identifier for the linked chat, i.e. the discussion group identifier for a channel and vice versa; for supergroups and channel chats. This identifier may be greater than 32 bits and some programming languages may have difficulty/silent defects in interpreting it. But it is smaller than 52 bits, so a signed 64 bit integer or double-precision float type are safe for storing this identifier. Returned only in :class:`aiogram.methods.get_chat.GetChat`."""
     location: Optional[ChatLocation] = None
     """*Optional*. For supergroups, the location to which the supergroup is connected. Returned only in :class:`aiogram.methods.get_chat.GetChat`."""
+
+    @property
+    def shifted_id(self) -> int:
+        """
+        Returns shifted chat ID (positive and without "-100" prefix).
+        Mostly used for private links like t.me/c/chat_id/message_id
+
+        Currently supergroup/channel IDs have 10-digit ID after "-100" prefix removed.
+        However, these IDs might become 11-digit in future. So, first we remove "-100"
+        prefix and count remaining number length. Then we multiple
+        -1 * 10 ^ (number_length + 2)
+        Finally, self.id is substracted from that number
+        """
+        short_id = str(self.id).replace("-100", "")
+        shift = int(-1 * pow(10, len(short_id) + 2))
+        return shift - self.id

aiogram/types/message.py

@@ -1760,6 +1760,25 @@ class Message(TelegramObject):
 
         return DeleteMessage(chat_id=self.chat.id, message_id=self.message_id)
 
+    def get_url(self, force_private: bool = False) -> Optional[str]:
+        """
+        Returns message URL. Cannot be used in private (one-to-one) chats.
+        If chat has a username, returns URL like https://t.me/username/message_id
+        Otherwise (or if {force_private} flag is set), returns https://t.me/c/shifted_chat_id/message_id
+
+        :param force_private: if set, a private URL is returned even for a public chat
+        :return: string with full message URL
+        """
+        if self.chat.type in ("private", "group"):
+            return None
+
+        if not self.chat.username or force_private:
+            chat_value = f"c/{self.chat.shifted_id}"
+        else:
+            chat_value = self.chat.username
+
+        return f"https://t.me/{chat_value}/{self.message_id}"
+
 
 class ContentType(helper.Helper):
     mode = helper.HelperMode.snake_case

tests/test_api/test_methods/test_get_url.py

@@ -0,0 +1,51 @@
+import datetime
+from typing import Optional
+
+import pytest
+from aiogram.types import Chat, Message
+
+from tests.mocked_bot import MockedBot
+
+
+class TestGetMessageUrl:
+    @pytest.mark.parametrize(
+        "chat_type,chat_id,chat_username,force_private,expected_result",
+        [
+            ["private", 123456, "username", False, None],
+            ["group", -123456, "username", False, None],
+            ["supergroup", -1001234567890, None, False, "https://t.me/c/1234567890/10"],
+            ["supergroup", -1001234567890, None, True, "https://t.me/c/1234567890/10"],
+            ["supergroup", -1001234567890, "username", False, "https://t.me/username/10"],
+            ["supergroup", -1001234567890, "username", True, "https://t.me/c/1234567890/10"],
+            ["channel", -1001234567890, None, False, "https://t.me/c/1234567890/10"],
+            ["channel", -1001234567890, None, True, "https://t.me/c/1234567890/10"],
+            ["channel", -1001234567890, "username", False, "https://t.me/username/10"],
+            ["channel", -1001234567890, "username", True, "https://t.me/c/1234567890/10"],
+            # 2 extra cases: 9-digit ID and 11-digit ID (without "-100")
+            ["supergroup", -100123456789, None, True, "https://t.me/c/123456789/10"],
+            ["supergroup", -10012345678901, None, True, "https://t.me/c/12345678901/10"],
+        ],
+    )
+    def test_method(
+        self,
+        bot: MockedBot,
+        chat_type: str,
+        chat_id: int,
+        chat_username: Optional[str],
+        force_private: bool,
+        expected_result: Optional[str],
+    ):
+
+        fake_chat = Chat(id=chat_id, username=chat_username, type=chat_type)
+        fake_message_id = 10
+        fake_message = Message(
+            message_id=fake_message_id,
+            date=datetime.datetime.now(),
+            text="test",
+            chat=fake_chat,
+        )
+
+        if expected_result is None:
+            assert fake_message.get_url(force_private=force_private) is None
+        else:
+            assert fake_message.get_url(force_private=force_private) == expected_result