module Watir
  class TaggedElementLocator
    include Watir
    include Watir::Exception

    def initialize(container, tag)
      @container = container
      @tag = tag
    end
    
    def set_specifier(how, what)    
      if how.class == Hash and what.nil?
        specifiers = how
      else
        specifiers = {how => what}
      end
        
      @specifiers = {:index => 1} # default if not specified

      specifiers.each do |how, what|  
        what = what.to_i if how == :index
        how = :href if how == :url
        how = :class_name if how == :class
        
        @specifiers[how] = what
      end

    end

    def each_element tag
      @container.document.getElementsByTagName(tag).each do |ole_element| 
        yield Element.new(ole_element) 
      end
    end    

    def locate
      index_target = @specifiers[:index]

      count = 0
      each_element(@tag) do |element|
        
        catch :next_element do
          @specifiers.each do |how, what|
            next if how == :index
            unless match? element, how, what
              throw :next_element
            end
          end
          count += 1
          unless index_target == count
            throw :next_element
          end
          return element.ole_object          
        end

      end # elements
      nil
    end
    
    def match?(element, how, what)
      begin 
        method = element.method(how)
      rescue NameError
        raise MissingWayOfFindingObjectException,
              "#{how} is an unknown way of finding a <#{@tag}> element (#{what})"
      end
      case method.arity
      when 0
        what.matches method.call
      when 1
       	method.call(what)
      else
        raise MissingWayOfFindingObjectException,
              "#{how} is an unknown way of finding a <#{@tag}> element (#{what})"
      end
    end

  end  
end