bulma/docs/_includes/components/pagination.html

{% assign currentLinkId = page.breadcrumb | last %}

{% assign currentCategoryIndex = page.breadcrumb | size | minus: 2 %}
{% assign currentCategoryId = page.breadcrumb[currentCategoryIndex] %}

{% assign sameCategoryIds = site.data.links.categories[currentCategoryId] %}
{% assign categorySize    = sameCategoryIds | size %}
{% assign lastIndex       = categorySize | minus: 1 %}

{% for categoryId in site.data.links.categoryIds %}
  {% if categoryId == currentCategoryId %}
    {% assign prevCategoryIndex = forloop.index0 | minus: 1 %}
    {% assign nextCategoryIndex = forloop.index0 | plus: 1 %}
  {% endif %}
{% endfor %}

{% for linkId in sameCategoryIds %}
  {% if linkId == currentLinkId %}
    {% assign prevIndex = forloop.index0 | minus: 1 %}
    {% assign nextIndex = forloop.index0 | plus: 1 %}
  {% endif %}
{% endfor %}

<!-- Previous link -->
<!-- If first index in list -->
{% if prevIndex == -1 %}
  {% assign prevCategoryId    = site.data.links.categoryIds[prevCategoryIndex] %}
  {% assign prevCategoryLinks = site.data.links.categories[prevCategoryId] %}
  {% assign prevCategorySize  = prevCategoryLinks | size %}
  {% assign prevLastIndex     = prevCategorySize | minus: 1 %}
  {% assign prevLinkId        = prevCategoryLinks[prevLastIndex] %}
{% else %}
  {% assign prevCategoryId = currentCategoryId %}
  {% assign prevLinkId = sameCategoryIds[prevIndex] %}
{% endif %}

<!-- Next link -->
<!-- If last index in list -->
{% if nextIndex == categorySize %}
  {% assign nextCategoryId = site.data.links.categoryIds[nextCategoryIndex] %}
  {% assign nextCategory   = site.data.links.categories[nextCategoryId] %}
  {% assign nextLinkId     = nextCategory[0] %}
{% else %}
  {% assign nextCategoryId = currentCategoryId %}
  {% assign nextLinkId = sameCategoryIds[nextIndex] %}
{% endif %}

{% unless page.hide_pagination %}
  {% if prevLinkId or nextLinkId %}
    <nav class="bd-docs-pagination bd-pagination-links">
      {% if prevLinkId %}
        {% assign prevLink = site.data.links.by_id[prevLinkId] %}
        <a
          class="button bd-fat-button is-primary is-light bd-pagination-prev"
          href="{{ site.url }}{{ prevLink.path }}"
          title="{{ prevLink.name }}"
        >
          <i>←</i>
          <span>
            <em>{{ prevCategoryId }}:</em>
            <strong>{{ prevLink.name }}</strong>
          </span>
        </a>
      {% endif %}

      {% if nextLinkId %}
        {% assign nextLink = site.data.links.by_id[nextLinkId] %}
        <a
          class="button bd-fat-button is-primary is-light bd-pagination-next"
          href="{{ site.url }}{{ nextLink.path }}"
          title="{{ nextLink.name }}"
        >
          <span>
            <em>{{ nextCategoryId }}:</em>
            <strong>{{ nextLink.name }}</strong>
          </span>
          <i>→</i>
        </a>
      {% endif %}
    </nav>
  {% endif %}
{% endunless %}