Implement conditions for members

[y9san9]

Right now that feature is already included in bot description, but is not done yet. So goal of this issue is to implement it.

Possible conditions

• subscriptions on some channels
• invite friends function

Conditions should be appeared in a giveaway description such as:

[TITLE]

Conditions:
- ...
- ...

[Participation hint]

[y9san9]

Invite friend function is like bot's killer-feature, it should work as following:

I am giveaway creator and posting giveaway message. If the invite friends feature is enabled, there will be additional SwitchInlineQueryInlineKeyboardButton "Invite friends" with text "[command]_[giveawayId]_[referralId]".

The inline result of such text will be article:

Invitation to channel from [fullname]:

If you join [link] the sender of this message will be able to participate in giveaway

With reply markup of "Joined" button.

When the user you sent this inline message join channel and click "Joined", bot will check if user actually was subscribed and then allow you to participate in giveaway (if required amount of invited users is reached).

When giveaway raffled, bot should check again if at least required amount of users are still subscribed to channel (you can invite actually 5 users when giveaway requires only 3, but if two of invited will leave channel, you still can be winner)

Also there should be additional callback data button "Check subscribers" with answer how many your subscribers are still subscribed

[y9san9]

Important: User should be able to be invited into channel only one time, so it requires to create new table referrals: userId to channelId

[y9san9]

Still working, a lot of work done, a lot of work still should be done.