{% assign author = page.author | default: page.authors | default: site.author %} {% if author %}

{% if author.name %}
  {% assign author_name = author.name %}
{% else %}
  {% if site.data.authors and site.data.authors[author] %}
    {% assign author_name = site.data.authors[author].name %}
  {% else %}
    {% assign author_name = author %}
  {% endif %}
{% endif %}

{% if author.picture %}
  {% assign author_picture = author.picture %}
{% else %}
  {% if site.data.authors and site.data.authors[author] %}
    {% assign author_picture = site.data.authors[author].picture %}
  {% endif %}
{% endif %}
{% assign author_picture = author_picture | relative_url %}

{% if author.twitter %}
  {% assign author_twitter = author.twitter %}
{% else %}
  {% if site.data.authors and site.data.authors[author] %}
    {% assign author_twitter = site.data.authors[author].twitter %}
  {% else %}
    {% assign author_twitter = site.twitter_username %}
  {% endif %}
{% endif %}

{% endif %}