module Producer
  module Core
    class Task
      class DSL
        class << self
          def evaluate(name, env, &block)
            dsl = new(&block)
            dsl.evaluate(env)
            Task.new(name, dsl.actions)
          end

          def define_action(keyword, klass)
            define_method(keyword) do |*args|
              @actions << klass.new(@env, *args)
            end
          end
        end

        define_action :echo,  Actions::Echo
        define_action :sh,    Actions::ShellCommand

        attr_accessor :actions

        def initialize(&block)
          @block    = block
          @actions  = []
        end

        def evaluate(env)
          @env = env
          instance_eval &@block
        rescue ConditionNotMetError
        end

        private

        def condition(&block)
          fail ConditionNotMetError unless block.call
        end
      end
    end
  end
end