module PowerTools
  
  module ActionController
    
    # Pilfered from Bruce Williams' (http://codefluency.com) plugin which now seems to be unavailable.
    module ParamTypes

      def self.included(base)
        base.instance_eval do
          @@param_type_handlers = {}
          cattr_accessor :param_type_handlers
          prepend_before_filter :convert_param_types
        end
        base.extend(ClassInstanceMethods)
      end

      module ClassInstanceMethods
        def add_param_type(name,&block)
          self.param_type_handlers[name.kind_of?(Regexp) ? name : name.to_s] = block
        end
        def handler_for_param_type(param_type)
          self.param_type_handlers.each do |criteria,handler|
            if param_type == criteria || (criteria.kind_of?(Regexp) && criteria.match(param_type))
              return handler
            end
          end
          return false
        end
      end

      def convert_param_types(object=params)
        if object.kind_of?(Hash)
          extra_params = {}
          object.each do |key,value|
            if match = /^(.+)\((.+)\)$/.match(key.to_s)
              new_key, param_type = match.captures
              if handler = ::ActionController::Base.handler_for_param_type(param_type)
                this_value = convert_param_types(object.delete(key))
                # If there's already a key by the same name in this hash (without a type)
                # whose value is an array add its values before calling the handler
                this_value = if this_value.kind_of?(Array) && object[new_key].kind_of?(Array)
                  this_value + object[new_key]
                else
                  this_value
                end
                case handler.arity
                when 1
                  object[new_key] = handler.call(this_value)
                when 3
                  handler.call(extra_params, new_key, this_value)
                end
              end
            else
              object[key] = convert_param_types(value)
            end
          end
          object.update(extra_params)
        end
        object
      end        

    end
  end
  
end