require 'sinatra/base'
require 'sinatra/url_for'

module Sinatra
  module StaticAssets
    # In HTML <link> and <img> tags have no end tag.
    # In XHTML, on the contrary, these tags must be properly closed.
    #
    # We can choose the appropriate behaviour with +closed+ option:
    #
    #   image_tag "/images/foo.png", :alt => "Foo itself", :closed => true
    #
    # The default value of +closed+ option is +false+.
    #
    def image_tag(source, options = {})
      options[:src] = url_for(source)
      tag("img", options)
    end

    def stylesheet_link_tag(*sources)
      list, options = extract_options(sources)
      list.collect { |source| stylesheet_tag(source, options) }.join("\n")
    end

    def javascript_script_tag(*sources)
      list, options = extract_options(sources)
      list.collect { |source| javascript_tag(source, options) }.join("\n")
    end
    
    def link_to(desc, url, options = {})
      tag("a", options.merge(:href => url_for(url))) do
        desc
      end
    end
    
    private
    
    def tag(name, options = {})
      start_tag = "<#{name}#{tag_options(options) if options}"
      if block_given?
        content = yield
        "#{start_tag}>#{content}</#{name}>"
      else
        "#{start_tag}/>"
      end
    end
    
    def tag_options(options)
      unless options.empty?
        attrs = []
        attrs = options.map { |key, value| %(#{key}="#{Rack::Utils.escape_html(value)}") }
        " #{attrs.sort * ' '}" unless attrs.empty?
      end
    end
    
    def stylesheet_tag(source, options = {})
      tag("link", { :type => "text/css",
            :charset => "utf-8", :media => "screen", :rel => "stylesheet",
            :href => url_for(source) }.merge(options))
    end
    
    def javascript_tag(source, options = {})
      tag("script", { :type => "text/javascript", :charset => "utf-8",
            :src => url_for(source) }.merge(options)) do
      end
    end
    
    def extract_options(a)
      opts = a.last.is_a?(::Hash) ? a.pop : {}
      [a, opts]  
    end

  end

  helpers StaticAssets
end