module Trigga
  module ParamFu
    def self.included(base)
      base.extend(ClassMethods)
      base.send(:include, InstanceMethods)
    end
    
    module ClassMethods
      def require_obj_or_id(opts, key)
        obj_or_id(opts,key)
        raise ArgumentError.new("#{key} or #{key_with_id(key)} are required") unless opts[key_with_id(key)]
        opts
      end
      
      def require_param(opts, *keys)
        keys.to_a.each do |k|
          raise ArgumentError.new("#{k} is required") unless opts[k]
        end
        opts
      end

      def obj_or_id(opts, key)
        opts[key_with_id(key)] ||= opts[key].id if opts[key]
      end
      
      def key_with_id(key)
        (key.to_s + '_id').to_sym
      end
      
      def require_one_of( opts, *keys )
        present = (opts.keys & keys)
        raise ArgumentError.new( "at least one of the arguments #{keys.inspect} is required" ) if present.empty?
        return present
      end
    end
    
    module InstanceMethods
      def require_obj_or_id(opts,key)
        self.class.require_obj_or_id(opts, key)
      end
      def obj_or_id(opts, key)
        self.class.obj_or_id(opts, key)
      end
      def require_param(opts, *keys)
        self.class.require_param(opts, *keys)
      end
      def require_one_of( opts, *keys )
        self.class.require_one_of( opts, *keys )
      end
    end
  end
end