Getting Started

Process creator authorization and download its channels memberships
Authorize supporter by his google account, check if has subscription to creator youtube channel, save his email and subscribed channel data

To get creator channel memberships application has to authorize creator using his google account:

run application: ./gradlew bootRun
go to login page: http://localhost:8080/login
click button: "login with google"
authorize with Tyrion Frey (test creator account)
after correct authorization and redirect to page http://localhost:8080/loginSuccess will be visible parsed memberships data in "Your channels members" section

Supporter youtube membership is verified using google authorization, and his email data is saved:

go to login page: http://localhost:8080/login
click button: "login with google"
authorize with supporter google auccount that join to some of creator youtube channel (for test purpose I used my google account and I manually hardcoded its channel in ChannelMembershipsRepository)
after correct authorization and redirect to page http://localhost:8080/loginSuccess will be visible supporter youtube channels ids, creators channels ids that supporter joined on youtube ("You have joined memberships for channels" section), and form for putting email address
email address included as default in form is address parsed from supporter google profile
it could be changed and submitted
after submitting it is saved and confirmation page is shown

google authorization is done using spring-security-web and spring-security-oauth2 libraries
google profile data, youtube user channels data and youtube memberships data are fetched using google apis, there are retrofit interfaces (for memberships api genereted from tapir definitions) and okhttp client is used.
data is stored in memory repositories implementation, so application restart forces memberships fetching rerun

wbaumann/-google-members-api-client