Add: --chat option now accepts invitation link

Author: Kostya K

README.md

@@ -26,7 +26,10 @@ Binaries for Linux, Windows and MacOS are available in [Releases](https://github
 ## Usage
 
 Mandatory parameters are <chat_name> e.g. @Python, @CSharp or a title of a dialogue, as seen in the UI, and <phone_num> - a telephone number. A phone number is needed for authentication and will not be stored anywhere. After the first successful authorization it will create telegram_chat_dump.session file containing auth token. The information from this file is being reused in next runs. If this is not a desirable behaviour, use -cl flag to delete session file on exit.
->Note: You can use telegram dialogue multi-word title like so: `--chat="Telegram Geeks"` with double quotes. However, when using multi-word title (rather than @channel_name), you need to join the channel first. Only then you will be able to dump it. This way you can dump __private__ dialogues which doesn't have @channel_name.
+>Note1: You can use telegram dialogue multi-word title like so: `--chat="Telegram Geeks"` with double quotes. However, when using multi-word title (rather than @channel_name), you need to join the channel first. Only then you will be able to dump it. This way you can dump __private__ dialogues which doesn't have @channel_name.
+
+>Note2: For private channels you can also pass an invitation link as chat name. E.g. `--chat="https://t.me/joinchat/XXXXXYYYYZZZZZ"`.
+__IMPORTANT__: It only works when you (the logged-in user) has already joined the private chat that the invitation link corresponds to.
 
 ```
 telegram-messages-dump -c <chat_name> -p <phone_num> [-l <count>] [-o <file>] [-cl]

telegram_messages_dump/chat_dump_settings.py

@@ -3,7 +3,7 @@
 """ This Module contains classes related to CLI interactions"""
 
 import argparse
-# import dateutil.parser
+from telegram_messages_dump.utils import JOIN_CHAT_PREFIX_URL
 
 
 class ChatDumpSettings:
@@ -72,9 +72,13 @@ def __init__(self, usage):
             parser.error('Exporter name is invalid.')
 
         # Default output file if not specified by user
-        out_file = 'telegram_{}.log'.format(args.chat)
-        if args.out:
+        OUTPUT_FILE_TEMPLATE = 'telegram_{}.log'
+        if args.out != '':
             out_file = args.out
+        elif args.chat.startswith(JOIN_CHAT_PREFIX_URL):
+            out_file = OUTPUT_FILE_TEMPLATE.format(args.chat.rsplit('/', 1)[-1])
+        else:
+            out_file = OUTPUT_FILE_TEMPLATE.format(args.chat)
 
         self.chat_name = args.chat
         self.phone_num = args.phone

telegram_messages_dump/telegram_dumper.py

@@ -20,6 +20,7 @@
 from telethon.errors.rpc_error_list import UsernameInvalidError
 from telethon.tl.functions.contacts import ResolveUsernameRequest
 from telegram_messages_dump.utils import sprint
+from telegram_messages_dump.utils import JOIN_CHAT_PREFIX_URL
 from telegram_messages_dump.exceptions import DumpingError
 from telegram_messages_dump.exceptions import MetadataError
 from telegram_messages_dump.exporter_context import ExporterContext
@@ -79,7 +80,7 @@ def run(self):
             except ValueError as ex:
                 ret_code = 1
                 self.logger.error('%s', ex,
-                              exc_info=self.logger.level > logging.INFO)
+                                  exc_info=self.logger.level > logging.INFO)
                 return
             # Fetch history in chunks and save it into a resulting file
             self._do_dump(chatObj)
@@ -144,6 +145,23 @@ def _getChannel(self):
         """
         name = self.settings.chat_name
 
+        # For private channуls try to resolve channel peer object from its invitation link
+        # Note: it will only work if the login user has already joined the private channel.
+        # Otherwise, get_entity will throw ValueError
+        if name.startswith(JOIN_CHAT_PREFIX_URL):
+            self.logger.debug('Trying to resolve as invite url.')
+            try:
+                peer = self.get_entity(name)
+                if peer:
+                    sprint('Invitation link "{}" resolved into channel id={}'.format(
+                        name, peer.id))
+                    return peer
+            except ValueError as ex:
+                self.logger.debug('Failed to resolve "%s" as an invitation link. %s',
+                                  self.settings.chat_name,
+                                  ex,
+                                  exc_info=self.logger.level > logging.INFO)
+
         if name.startswith('@'):
             name = name[1:]
             self.logger.debug('Trying ResolveUsernameRequest().')

telegram_messages_dump/utils.py

@@ -10,3 +10,6 @@ def sprint(string, *args, **kwargs):
         string = string.encode('utf-8', errors='ignore') \
             .decode('ascii', errors='ignore')
         print(string, *args, **kwargs)
+
+
+JOIN_CHAT_PREFIX_URL = 'https://t.me/joinchat/'