module Doorkeeper::Request

def authorization_strategy(response_type)
  build_strategy_class(response_type)
end

def build_strategy_class(grant_or_request_type)
  strategy_class_name = grant_or_request_type.to_s.tr(" ", "_").camelize
  "Doorkeeper::Request::#{strategy_class_name}".constantize
end

def get_strategy(grant_type, available)
  raise NameError unless available.include?(grant_type.to_s)
  build_strategy_class(grant_type)
end

def token_grant_types
  Doorkeeper.config.token_grant_types
end

def token_strategy(grant_type)
  raise Errors::MissingRequiredParameter, :grant_type if grant_type.blank?
  get_strategy(grant_type, token_grant_types)
rescue NameError
  raise Errors::InvalidTokenStrategy
end