module OpenGraphHelper
  def og_title(post)
    meta_tag_with_property('og:title', post_page_title(post, :length => 140))
  end

  def og_type(post)
    meta_tag_with_property('og:type', 'article')
  end

  def og_url(post)
    meta_tag_with_property('og:url', post_url(post))
  end

  def og_image(post)
    tags = post.photos.map{|x| meta_tag_with_property('og:image', x.url(:thumb_large))}
    tags << meta_tag_with_property('og:image', default_image_url) if tags.empty?
    tags.join(' ')
  end

  def og_site_name
    meta_tag_with_property('og:site_name', 'Diaspora*')
  end

  def og_description(post)
    meta_tag_with_property('og:description', post_page_title(post, :length => 1000))
  end

  def og_type
    # the diaspora og namespace was already taken :(
    meta_tag_with_property('og:type', 'joindiaspora:post')
  end

  def og_page_specific_tags(post)
    [og_title(post), og_type,
      og_url(post), og_image(post), 
      og_description(post)].join(' ').html_safe
  end

  def meta_tag_with_property(name, content)
    content_tag(:meta, '', :property => name, :content => content)
  end

  private

  # This method compensates for hosting assets off of s3
  def default_image_url
    if image_path('asterisk.png').include?("http")
      image_path('asterisk.png')
    else
      "#{root_url.chop}#{image_path('asterisk.png')}"
    end
  end
end