# Title: Simple Image tag for Jekyll

 # Authors: Brandon Mathis http://brandonmathis.com
 #          Felix Schäfer, Frederic Hemberger
 # Description: Easily output images with optional class names, width, height, title and alt attributes

 #

 # Syntax {% img [class name(s)] [http[s]:/]/path/to/image [width [height]] [title text | "title text" ["alt text"]] %}

 #

 # Examples:
 # {% img /images/ninja.png Ninja Attack! %}
 # {% img left half http://site.com/images/ninja.png Ninja Attack! %}
 # {% img left half http://site.com/images/ninja.png 150 150 "Ninja Attack!" "Ninja in attack posture" %}

 #
 # Output:

 # <img src="/images/ninja.png">
 # <img class="left half" src="http://site.com/images/ninja.png" title="Ninja Attack!" alt="Ninja Attack!">
 # <img class="left half" src="http://site.com/images/ninja.png" width="150" height="150" title="Ninja Attack!" alt="Ninja in attack posture">

 #
 
 module Jekyll
 
   class ImageTag < Liquid::Tag
     @img = nil
 
     def initialize(tag_name, markup, tokens)

       attributes = ['class', 'src', 'width', 'height', 'title']
 
       if markup =~ /(?<class>\S.*\s+)?(?<src>(?:https?:\/\/|\/|\S+\/)\S+)(?:\s+(?<width>\d+))?(?:\s+(?<height>\d+))?(?<title>\s+.+)?/i
         @img = attributes.reduce({}) { |img, attr| img[attr] = $~[attr].strip if $~[attr]; img }

         if /(?:"|')(?<title>[^"']+)?(?:"|')\s+(?:"|')(?<alt>[^"']+)?(?:"|')/ =~ @img['title']
           @img['title']  = title
           @img['alt']    = alt

         else

           @img['alt']    = @img['title'].gsub!(/"/, '"')

         end

         @img['class'].gsub!(/"/, '')

       end
       super
     end
 
     def render(context)
       if @img

         "<img #{@img.collect {|k,v| "#{k}=\"#{v}\"" if v}.join(" ")}>"

       else

         "Error processing input, expected syntax: {% img [class name(s)] [http[s]:/]/path/to/image [width [height]] [title text | \"title text\" [\"alt text\"]] %}"

       end
     end
   end
 end
 
 Liquid::Template.register_tag('img', Jekyll::ImageTag)