{% assign default_author = site.data.config.default_author | default: site.theme_config.default_author %}
{% assign github_username = site.github.owner_name %}
{% assign author_name = include.author | default: default_author | default: github_username %}
{% assign author = site.data.authors[author_name] %}
{% assign author_link = author.links.first[1] %}

{% if author_name %}
  •
  <span itemprop="author" itemscope itemtype="http://schema.org/Person">
    <span itemprop="name">

      {% if author %}
        {% if author_link %}
          <a href="{{ author_link }}" title="{{ author.name }}">{{ author.name }}</a>
        {% else %}
          {{ author.name }}
        {% endif %}
      {% else %}
        {{ author_name | default: "unknown author" }}
      {% endif %}
    </span>
  </span>
{% endif %}