module Converters

  def flickr(string, options = {})
    # https://www.flickr.com/photos/fotokunstsusanne/23160248869

    {:maxwidth => nil, :maxheight => nil, :link_options => {}}.merge(options)
    @regex = %r{https?://(www\.)?flickr\.com/photos/[^\s<]*}

    string.gsub(@regex) do |match|
      params = { :url => match, :format => "json" }
      [:maxwidth, :maxheight].each{|p| params[p] = options[p] unless options[p].nil? or !options[p] > 0}

      uri = URI("http://www.flickr.com/services/oembed")
      uri.query = URI.encode_www_form(params)

      response = JSON.parse(Net::HTTP.get(uri))

      link_options = Array(options[:link_options]).reject { |k,v| v.nil? }.map { |k, v| %{#{k}="#{REXML::Text::normalize(v)}"} }.join(' ')
      %{<a href="#{match}"#{ ' ' + link_options unless link_options.empty? }><img src="#{response["url"]}" alt="#{response["title"]}" title="#{response["title"]}" /></a>}
    end
  end

end