# a configuration error
class Restfulie::Client::Mikyung::ConfigurationError < Restfulie::Common::Error::RestfulieError
end

# Provides a DSL to build your process in a human readable way.
#
# Example:
# When there is a machine
# And  already installed
# Then reboot
#
# Before creating your DSL you should provide your method content:
#
# When /there (are|is an|is a|is) (.*)/ do |resource, regex|
#   resource.keys.first==regex[2]
# end
# 
# When "already installed" do |resource|
#   @installed
# end
# 
# Then "reboot" do |resource|
#   resource.machine.boot.post! :boot => {:reason => "Installed #{@software[:name]}"}
# end
class Restfulie::Client::Mikyung::RestProcessModel
  
  # concatenates anything to a current expression
  def method_missing(sym, *args)
    Restfulie::Client::Mikyung::Concatenator.new(sym.to_s, *args)
  end
  
  # the list of results
  def then_rules
    @then_rules ||= []
  end
  
  # the list of conditions
  def conditions
    @conditions ||= []
  end
  
  # the list of conditional rules
  def when_rules
    @when_rules ||= []
  end
  
  # creates a When rule or block
  #
  # When blocks should return true or false whether the current resource matches what you expect:
  # When /there (are|is an|is a|is) (.*)/ do |resource, regex|
  #   resource.keys.first==regex[2]
  # end
  #
  # When rules will group conditions and rules together:
  # When there is a machine
  # And  already installed
  # Then reboot
  def When(concat, &block)
    if concat.respond_to? :content
      @condition = when_factory(concat)
      conditions << @condition
    else
      when_rules << [concat, block]
    end
  end
  
  # Adds a constraint to the current scenario
  def And(concat)
    @condition.and when_factory(concat)
  end
  
  # Adds a negative constraint to the current scenario
  def But(concat)
    @condition.but when_factory(concat)
  end
  
  # Creates a result rule
  #
  # example:
  # Then "reboot" do |resource|
  #   resource.machine.boot.post! :boot => {:reason => "Installed #{@software[:name]}"}
  # end
  def Then(concat, &block)
    if concat.respond_to? :content
      @condition.results_on Restfulie::Client::Mikyung::ThenCondition.new(concat.content)
    else
      then_rules << [concat, block]
    end
  end

  # Goes through every scenario and finds which one fits the current server steady state.
  # Picks this step and executes the business rule attached to it.
  def next_step(resource, mikyung)
    conditions.each do |c|
      if c.should_run_for(resource, self)
        return c.execute(resource, self, mikyung)
      end
    end
    nil
  end
  
  private
  
  def when_factory(concat)
    rule = when_rules.find do |rule|
      concat.content.match(rule[0])
    end
    if rule.nil?
      raise Restfulie::Client::Mikyung::ConfigurationError, "You forgot to create '#{concat.content}' prior to its usage."
    end
    Restfulie::Client::Mikyung::WhenCondition.new(concat.content, rule, concat.content.match(rule[0]))
  end

end