module GoogleCells

# File lib/google_cells.rb, line 24
def self.configure
  self.config ||= Configuration.new
  yield(config)

  self.client = Google::APIClient.new(
    :application_name => 'GoogleCells App',
    :application_version => '0.0.3'
  )
  if config.path_to_credentials_file
    config_from_file
  elsif config.client_id
    config_web_application
  else
    config_service_account
  end
  client.authorization.scope = ['https://www.googleapis.com/auth/drive',
    'https://spreadsheets.google.com/feeds']
  client.authorization.token_credential_uri = 'https://accounts.google.com/o/oauth2/token'

  config
end

# File lib/google_cells.rb, line 75
def self.config_from_file
  flow = Google::APIClient::FileStorage.new(
    :path => config.path_to_credentials_file
  )
  client.authorization = flow.authorize
end

# File lib/google_cells.rb, line 65
def self.config_service_account
  key = Google::APIClient::KeyUtils.load_from_pkcs12(config.key_file, 
    config.key_secret)
  opts = { issuer: config.service_account_email,
    signing_key: key }

  client.authorization = Signet::OAuth2::Client.new(opts)
  client.authorization.audience = 'https://accounts.google.com/o/oauth2/token'
end

# File lib/google_cells.rb, line 60
def self.config_web_application
  client.authorization.client_id = config.client_id
  client.authorization.client_secret = config.client_secret
end