post-footer.html

{% if include.page_en_url %}
  {% assign current_page_en_url = include.page_en_url %}
{% else %}
  {% assign current_page_en_url = page.url %}
{% endif %}

{% comment %}
  Loop through all the chapters in order to:
    - create full array of chapters
    - index english version of current chapter
{% endcomment %}

{% assign all_chapters = "" | split: "" %}
{% assign current = 0 %}
{% for sections in site.data.chapterlist %}
  {% assign chapters = sections[1].chapters %}
  {% for chapter in chapters %}
    {% if chapter.url == current_page_en_url %}
      {% assign index = current %}
    {% endif %}
    {% assign all_chapters = all_chapters | push: chapter %}
    {% assign current = current | plus: 1 %}
    {% for subchapter in chapter.subchapters %}
      {% if subchapter.url == current_page_en_url %}
        {% assign index = current %}
      {% endif %}
      {% assign all_chapters = all_chapters | push: subchapter %}
      {% assign current = current | plus: 1 %}
    {% endfor %}
  {% endfor %}
{% endfor %}

{% assign size = all_chapters | size %}

<div class="post-footer">
  <hr />

  {% assign previous = index | minus: 1 %}
  {% if previous != -1 %}

    {% comment %} Set previous page based on current index {% endcomment %}

    {% assign previous_url = all_chapters[previous].url %}

    {% comment %} If non-english, find page same language previous page {% endcomment %}
    {% if page.lang != "en" %}

      {% comment %} If non-english, find ref of previous page {% endcomment %}

      {% assign prev_pages = site.chapters | where:"url", previous_url %}
      {% assign prev_page_ref = prev_pages[0].ref %}
      {% if prev_page_ref %}

        {% comment %} Find chapter of matching language and ref {% endcomment %}

        {% assign cur_lang_pages = site.chapters | where:"ref", prev_page_ref | where:"lang", page.lang %}
        {% if cur_lang_pages[0] %}
          {% assign previous_url = cur_lang_pages[0].url %}
        {% endif %}
      {% endif %}
    {% endif %}

    <a class="previous" href="{{ previous_url }}">
      &larr; Previous
    </a>
  {% endif %}

  <a class="toc" href="{% link guide.md %}#table-of-contents">Table of Contents</a>

  {% assign next = index | plus: 1 %}
  {% if next != size %}

    {% comment %} Set next page based on current index {% endcomment %}

    {% assign next_url = all_chapters[next].url %}

    {% comment %} If non-english, find page same language next page {% endcomment %}
    {% if page.lang != "en" %}

      {% comment %} If non-english, find ref of next page {% endcomment %}

      {% assign next_pages = site.chapters | where:"url", next_url %}
      {% assign next_page_ref = next_pages[0].ref %}
      {% if next_page_ref %}

        {% comment %} Find chapter of matching language and ref {% endcomment %}

        {% assign cur_lang_pages = site.chapters | where:"ref", next_page_ref | where:"lang", page.lang %}
        {% if cur_lang_pages[0] %}
          {% assign next_url = cur_lang_pages[0].url %}
        {% endif %}
      {% endif %}
    {% endif %}

    <a class="next" href="{{ next_url }}">Next &rarr;</a>
  {% endif %}

</div>