require 'googleauth'

# Get the environment configured authorization
scopes =  ['https://www.googleapis.com/auth/cloud-platform',
           'https://www.googleapis.com/auth/compute']
authorization = Google::Auth.get_application_default(scopes)

# Add the the access token obtained using the authorization to a hash, e.g
# headers.
some_headers = {}
authorization.apply(some_headers)

require 'googleauth'
require 'googleauth/web_user_authorizer'
require 'googleauth/stores/redis_token_store'
require 'redis'

client_id = Google::Auth::ClientId.from_file('/path/to/client_secrets.json')
scope = ['https://www.googleapis.com/auth/drive']
token_store = Google::Auth::Stores::RedisTokenStore.new(redis: Redis.new)
authorizer = Google::Auth::WebUserAuthorizer.new(
  client_id, scope, token_store, '/oauth2callback')


get('/authorize') do
  # NOTE: Assumes the user is already authenticated to the app
  user_id = request.session['user_id']
  credentials = authorizer.get_credentials(user_id, request)
  if credentials.nil?
    redirect authorizer.get_authorization_url(login_hint: user_id, request: request)
  end
  # Credentials are valid, can call APIs
  # ...
end

get('/oauth2callback') do
  target_url = Google::Auth::WebUserAuthorizer.handle_auth_callback_deferred(
    request)
  redirect target_url
end

require 'googleauth'
require 'googleauth/stores/file_token_store'

OOB_URI = 'urn:ietf:wg:oauth:2.0:oob'

scope = 'https://www.googleapis.com/auth/drive'
client_id = Google::Auth::ClientId.from_file('/path/to/client_secrets.json')
token_store = Google::Auth::Stores::FileTokenStore.new(
  :file => '/path/to/tokens.yaml')
authorizer = Google::Auth::UserAuthorizer.new(client_id, scope, token_store)

user_id = ENV['USER']
credentials = authorizer.get_credentials(user_id)
if credentials.nil?
  url = authorizer.get_authorization_url(base_url: OOB_URI )
  puts "Open #{url} in your browser and enter the resulting code:"
  code = gets
  credentials = authorizer.get_and_store_credentials_from_code(
    user_id: user_id, code: code, base_url: OOB_URI)
end

# OK to use credentials

scope = 'https://www.googleapis.com/auth/androidpublisher'

authorizer = Google::Auth::ServiceAccountCredentials.make_creds(
  json_key_io: File.open('/path/to/service_account_json_key.json'),
  scope: scope)

authorizer.fetch_access_token!

require 'googleauth'
require 'google/apis/drive_v3'

Drive = ::Google::Apis::DriveV3
drive = Drive::DriveService.new

scope = 'https://www.googleapis.com/auth/drive'

authorizer = Google::Auth::ServiceAccountCredentials.from_env(scope: scope)
drive.authorization = authorizer

list_files = drive.list_files()

scope = 'https://www.googleapis.com/auth/androidpublisher'

authorizer = Google::Auth::ServiceAccountCredentials.make_creds(
  json_key_io: File.open('/path/to/service_account_json_key.json'),
  scope: scope
)
authorizer.update!(sub: "email-to-impersonate@your-domain.com")

authorizer.fetch_access_token!

require 'googleauth'
require 'google/apis/drive_v3'

Drive = ::Google::Apis::DriveV3
drive = Drive::DriveService.new

# Auths with ENV vars:
# "GOOGLE_CLIENT_ID",
# "GOOGLE_CLIENT_EMAIL",
# "GOOGLE_ACCOUNT_TYPE", 
# "GOOGLE_PRIVATE_KEY"
auth = ::Google::Auth::ServiceAccountCredentials
  .make_creds(scope: 'https://www.googleapis.com/auth/drive')
drive.authorization = auth

list_files = drive.list_files()