module CostQuery::Validation
  def register_validations(validation_methods)
    validation_methods.each do |val_method|
      const_name = val_method.to_s.camelize
      begin
        val_module = CostQuery::Validation.const_get const_name
        metaclass.send(:include, val_module)
        val_method = "validate_" + val_method.to_s
        if method(val_method)
          validations << val_method
        else
          warn "#{val_module.name} does not define #{val_method}"
        end
      rescue NameError
        warn "No Module CostQuery::Validation::#{const_name} found to validate #{val_method}"
      end
    end
  end
  
  def errors
    @errors ||= []
    @errors
  end

  def validations
    @validations ||= []
    @validations
  end

  def validate(values = [])
    errors.clear
    return true if validations.empty?
    validations.all? do |validation|
      send(validation, values) unless values.empty?
    end
  end

end