Need Expert with FCM cloud messaging for my existing Android app

Need a expert who know firebase topic messaging ( Android Studio ) very well. please do not bid if you not expert in this topic. I has a small and simple android app for communicate with my clients. Now you want to develop a single screen, admin to send text and image messages to users. The app has 2 parts : 1. for (Admin ) posting my products, and display to customers, who installed my app ( Guest) and Users [ logged in with mobile number verification]. -> this part already done. 2. second part is to send text and image messages using firebase topic messages. Now you want to do this part like whatsapp. 2a : there are 3 types of app user. 1. Guest ( Just app installer ), 2. User ( Who verified their mobile number ) and 3. Admin ( Who has full permission to post products and send messages to user. ) 2b : app have one chat screen, but Admin only can send text and images by this screen. and User only get these messages. ( not for guest ). 2c: so user auto subscribe to "broadcast_messages" topic when they mobile verified. ( Admin will send messages to this topic, and user only will get.) 2d: notification should appear when new message arrive to user. if they click on it app should open with broadcast screen with text or image messages. 2e: all messages should save in users device's sqlite table for offline view. same time images should download their device like whatsapp. 2f: images can upload to server ( if admin send image ) 2g: 3 dots on top right corner for clear sent ( for admin ) and received ( for user ) messages. 2h: received images ( user ) can view with zoom. 2i : app have logout feature, if user log out they become as just guest, so automatically they unsubscribe to "broadcast_messages" topic, and no longer they receive these messages. I am expecting very well known freelancer, so don't apply who don't know firebase correctly. And my budget is fixed ( 100 $ ), don't expect extra. and correctly mention your timeline. Milestone will release only after you provide perfect app and delivered source code.