module AuthStrategist
  class Authorize
    attr_reader :strategy

    def self.call(options = {})
      new(options).call
    end

    def initialize(options = {})
      @strategy = choose_strategy(options)
    end

    def call
      strategy.authorize!
    end

    private

    def choose_strategy(options = {})
      strategy_name = options.delete(:strategy)
      raise(strategy_name_blank) if strategy_name.nil?

      strategy_class = strategies[strategy_name]
      raise(strategy_not_found(strategy_name)) if strategy_class.nil?

      strategy_class.new(options)
    end

    def strategies
      AuthStrategist.strategies.to_h
    end

    def strategy_not_found(strategy_name)
      StandardError.new("Strategy :#{strategy_name} was not found.")
    end

    def strategy_name_blank
      StandardError.new(':strategy option must not be blank.')
    end
  end
end