local_auth_flow_google.rb

# Google docs query command-line sample.

require 'google/apis/drive_v2'
require 'google/api_client/client_secrets'
require 'google/api_client/auth/installed_app'
require 'google/api_client/auth/storage'
require 'google/api_client/auth/storages/file_store'
require 'logger'
require 'json'

CREDENTIAL_STORE_FILE = "#{$0}-oauth2.json"

# Handles authentication and loading of the API.
def setup
  storage = Google::APIClient::Storage.new(
    Google::APIClient::FileStore.new(CREDENTIAL_STORE_FILE))
  storage.authorize
  if storage.authorization.nil?
    client_secrets = Google::APIClient::ClientSecrets.load
    # The InstalledAppFlow is a helper class to handle the OAuth 2.0 installed
    # application flow, which ties in with Stroage to store credentials
    # between runs.
    flow = Google::APIClient::InstalledAppFlow.new(
      :client_id => client_secrets.client_id,
      :client_secret => client_secrets.client_secret,
      :scope => ['https://www.googleapis.com/auth/drive.metadata.readonly']
    )
    flow.authorize(storage)
  end
  return storage.authorization
end

def dump_files(auth_client)
  drive = Google::Apis::DriveV2::DriveService.new
  files = drive.list_files(options: { authorization: auth_client })
  puts JSON.pretty_generate(files.to_h)
end


if __FILE__ == $0
  authorization = setup()
  dump_files(authorization)
end