This bot handles, processes, and forwards messages from a number of group chats to a single group chat to create some kind of a knowledge base. The bot automatically finds hashtags in messages sent to source chats, and forwards a message to one or more topic in the source group based on the hashtags found.

Built using the python-telegram-bot library v21, tested and run on Ubuntu 22.04 with Python v3.11.4.

1. Support media group forwarding https://github.com/python-telegram-bot/python-telegram-bot/wiki/Frequently-requested-design-patterns#how-do-i-deal-with-a-media-group
   Here https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L131
   And here https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L215 (see also point 3 below)
2. Disallow any /save command arguments except hashtags. It should be impossible to type /save sometext. Only /save #tag1 #tag2 should be allowed.
   Here https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L197
3. Research why saving images and files without any caption doesn't work properly when saving using the /save command with arguments
   Here https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L215
4. Support regular expressions to search hashtags instead of hashtags = [word for word in context.args if word[0]=='#' and len(word) > 1].
   Here and across the whole script https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L217C21-L217C97
5. Add .lowercase to all entries of thread_id = HASHTAG_THREAD_MAP.get(tag, None) to ignore hashtag cases when sending messages to the target group.
   Here and in other places https://github.com/AlexJameson/auto-forwarder-bot/blob/main/bot.py#L137

Basically, the bot listens to all messages in source groups, parses these messages to find hashtags, and then sends messages to each topic that corresponds to a message hashtags. The bot ignores messages in the following cases:

1. A text message content consists only of hashtags without any other text (while it's a valid case for photos or document captions);
2. Hashtags in the message are shorter than 4 symbols including the hash symbol, like #1 or #hh.

In case a message contains valid hashtags and content but the hashtags don't correspond to any topics in the target group, the bot forwards this message to the Miscellaneous topic.

For more information on this process, see Hashtags and Topics.

Sometimes you might want to save a message that initially didn't have any hashtags, or these hashtags were added later when the author edited the message. Then you can send the /save command as a reply to the message you want to forward to the target chat.

You can call the /save command either without arguments or pass any number of space-separated hashtags. Let's see these two cases in more detail:

• You see a message that contains one or more hashtags, and you want to save this message. To forward the message, just reply to it with the /save command, and the bot will send it to all corresponding topics based on the hashtags in the message.

• You see a message that is of interest but doesn't contain any hashtags. In this case, you can reply to this message with the /save command with a sequence of space-separated hashtags as follows: /save #knowledge #text #tools. The bot will forward the message to which you reply to all corresponding topics, once to each topic.

  When you use this method, the bot ignores the message content and selects target topics based only on hashtags passed as arguments. See the full list of available hashtags in the Hashtags and Topics section.

The bot tries to map the hashtags received to the values from a from a predefined dictionary. This dictionary contains hashtags and corresponding topic IDs. Hashtags are unique and serve as keys while the topic IDs can repeat so that a single topic can contain messages having several different hashtags.

You don't need topic IDs until you want to contribute to the above mentioned dictionary. The bot accepts only hashtags as command arguments.

If a message has one or more hashtags that are not listed in the table below, and has no messages from the table, the bot sends such message to the Miscellaneous topic whose ID is 30.

The following table displays available hashtags, topics, and topic IDs (in Russian):