require 'ext/string'
module PageMagic
  module Elements
    class InvalidElementNameException < Exception
    end

    class InvalidMethodNameException < Exception
    end

    def self.extended clazz
      clazz.class_eval do
        unless instance_methods.include?(:browser_element)
          attr_reader :browser_element
        end

        def element_definitions
          self.class.element_definitions
        end
      end
    end

    def method_added method
      raise InvalidMethodNameException, "method name matches element name" if element_definitions[method]
    end

    def elements(browser_element, *args)
      element_definitions.values.collect { |definition| definition.call(browser_element, *args) }
    end

    TYPES = [:element, :text_field, :button, :link, :checkbox, :select_list, :radios, :textarea, :section]
    TYPES.each do |type|
      define_method type do |*args, &block|

        first_arg = args.first
        if first_arg.is_a?(Symbol)
          name, selector = args

          add_element_definition(name) do |*args_for_block|
            page_section = PageMagic::Element.new name, args_for_block.delete_at(0), type, selector
            page_section.instance_exec *args_for_block, &(block || Proc.new {})
            page_section
          end

        elsif first_arg < PageMagic::Element
          section_class, name, selector = args

          unless selector
            selector = section_class.selector
            name = section_class.name.to_snake_case.to_sym
          end

          add_element_definition(name) do |parent_browser_element|
            section_class.new(name, parent_browser_element, :section, selector|| section_class.selector)
          end

        end
      end
    end

    def add_element_definition name, &block
      raise InvalidElementNameException, "duplicate page element defined" if element_definitions[name]

      methods = respond_to?(:instance_methods) ? instance_methods : methods()
      raise InvalidElementNameException, "a method already exists with this method name" if methods.find { |method| method == name }

      element_definitions[name] = block
    end

    def element_definitions
      @element_definitions ||= {}
    end
  end
end