{%- comment -%}
  Include as: {%- include css/activation.scss.liquid -%}
  Depends on: page, site.
  Results in: page-dependent (non-nested) CSS rules for inclusion in a head style element,
    which needs to be suppressed when JS is enabled.
  Includes:
    sorted_pages.html.
  Overwrites: 
    activation_no_nav_link, activation_pages, activation_pages_top_size, activation_page, activation_title,
    activation_first_level, activation_second_level, activation_third_level,
    activation_first_level_reversed, activation_second_level_reversed,
    activation_first_level_index, activation_second_level_index, activation_third_level_index,
    activation_index, activation_collection_prefix, activation_other_collection_prefix.
  Should not be cached, because it depends on page.
  (For a site with only top-level pages, the rendering of this file is always empty.
  This property could be detected, and used to reduce the build time for such sites.)
{%- endcomment -%}

{%- comment -%}
  The CSS rules in activation_no_nav_link are for use on pages excluded from the main navigation.
  - The first rule ensures that no nav-link has a background image.
  - The other two rules ensure that all folding collections are expanded.
{%- endcomment -%}

{%- capture activation_no_nav_link %}
.site-nav ul li a {
  background-image: none;
}

{%- if site.just_the_docs.collections %}
.site-nav > ul.nav-category-list > li > button svg {
  transform: rotate(-90deg);
}
.site-nav > ul.nav-category-list > li.nav-list-item > ul.nav-list {
  display: block;
}
{%- endif %}
{% endcapture -%}

{%- if page.title == nil or page.nav_exclude == true -%}

{{ activation_no_nav_link }}

{%- else -%}

{%- assign activation_pages = site[page.collection]
      | default: site.html_pages
      | where_exp: "item", "item.title != nil"
      | where_exp: "item", "item.nav_exclude != true" -%}

{%- assign activation_first_level_index = nil -%}
{%- assign activation_second_level_index = nil -%}
{%- assign activation_third_level_index = nil -%}
{%- assign activation_first_level_reversed = nil -%}
{%- assign activation_second_level_reversed = nil -%}

{%- comment -%}
  The generated CSS depends on the position of the current page in each level in
  the navigation.
{%- endcomment -%}

{%- assign activation_title = page.grand_parent | default: page.parent | default: page.title -%}
{%- assign activation_first_level = activation_pages
      | where_exp: "item", "item.parent == nil" -%}
{%- include sorted_pages.html pages = activation_first_level -%}
{%- for activation_page in sorted_pages -%}
  {%- if activation_page.title == activation_title -%}
    {%- assign activation_first_level_index = forloop.index -%}
    {%- assign activation_first_level_reversed = activation_page.child_nav_order -%}
    {%- break -%}
  {%- endif -%}
{%- endfor -%}

{%- if activation_first_level_index == nil -%}

{{ activation_no_nav_link }}

{%- else -%}

{%- if page.grand_parent -%}
  {%- assign activation_title = page.parent -%}
  {%- assign activation_second_level = activation_pages
        | where_exp: "item", "item.grand_parent == nil"
        | where_exp: "item", "item.parent == page.grand_parent" -%}
{%- elsif page.parent -%}
  {%- assign activation_title = page.title -%}
  {%- assign activation_second_level = activation_pages
        | where_exp: "item", "item.grand_parent == nil"
        | where_exp: "item", "item.parent == page.parent" -%}
{%- endif -%}
{%- if page.parent -%}
  {%- include sorted_pages.html pages = activation_second_level -%}
  {%- for activation_page in sorted_pages -%}
    {%- if activation_page.title == activation_title -%}
      {%- assign activation_second_level_index = forloop.index -%}
      {%- assign activation_second_level_reversed = activation_page.child_nav_order -%}
      {%- if activation_first_level_reversed -%}
        {%- assign activation_second_level_index = sorted_pages | size | plus: 1 | minus: activation_second_level_index -%}
      {%- endif -%}
      {%- break -%}
    {%- endif -%}
  {%- endfor -%}
{%- endif -%}

{%- if page.grand_parent -%}
  {%- assign activation_third_level = activation_pages
        | where_exp: "item", "item.parent == page.parent"
        | where_exp: "item", "item.grand_parent == page.grand_parent" -%}
  {%- include sorted_pages.html pages = activation_third_level -%}
  {%- assign activation_third_level = sorted_pages -%}
  {%- for activation_page in sorted_pages -%}
    {%- if activation_page.title == page.title -%}
      {%- assign activation_third_level_index = forloop.index -%}
      {%- if activation_second_level_reversed -%}
        {%- assign activation_third_level_index = sorted_pages | size | plus: 1 | minus: activation_third_level_index -%}
      {%- endif -%}
      {%- break -%}
    {%- endif -%}
  {%- endfor -%}
{%- endif -%}

{%- if activation_second_level_index == nil and activation_third_level_index -%}

{{ activation_no_nav_link }}

{%- else -%}

{%- comment -%}
  The site-nav is:
  - an optional ul.nav-list with li.nav-list-items for non-collection top-level pages
  - an optional ul.nav-list with li.nav-list-item.externals
  - any number of just-the-docs.collections
  
  A non-foldable collection is:
  - a div.nav-category with the collection name, followed by:
  - a ul.nav-list with li.nav-list-items for its top-level pages
  
  A foldable collection is:
  - a ul.nav-list.nav-category-list with a single li.nav-list-item containing:
    - an optional button with the expander svg
    - a div.nav-category with the collection name
    - a ul.nav-list with li.nav-list-items for its top-level pages
  
  The generated CSS uses:
  - activation_collection_prefix, to select the site-nav > ul.nav-list for the page
  - activation_other_collection_prefix, to select all the other site-nav > ul.nav-lists
{%- endcomment -%}

{%- if page.collection == nil -%}

  {%- capture activation_collection_prefix -%}
  .site-nav > ul.nav-list:first-child
  {%- endcapture -%}

  {%- capture activation_other_collection_prefix -%}
  .site-nav > ul.nav-list:not(:first-child)
  {%- endcapture -%}

{%- else -%}

  {%- for activation_collection in site.just_the_docs.collections -%}
    {%- if activation_collection[0] == page.collection -%}
      {%- assign activation_index = forloop.index -%}
      {%- break -%}
    {%- endif -%}
  {%- endfor -%}

  {%- assign activation_pages_top_size = site.html_pages
          | where_exp:"item", "item.title != nil"
          | where_exp:"item", "item.parent == nil"
          | where_exp:"item", "item.nav_exclude != true"
          | size -%}
  {%- if activation_pages_top_size > 0 -%}
    {%- assign activation_index = activation_index | plus: 1 -%}
  {%- endif -%}

  {%- if site.nav_external_links -%}
    {%- assign activation_index = activation_index | plus: 1 -%}
  {%- endif -%}

  {%- capture activation_collection_prefix -%}
  .site-nav > ul:nth-of-type({{ activation_index }})
  {%- if site.just_the_docs.collections[page.collection].nav_fold %} > li > ul
  {%- endif -%}
  {%- endcapture -%}

  {%- capture activation_other_collection_prefix -%}
  .site-nav > ul:not(:nth-of-type({{ activation_index }}))
  {%- endcapture -%}

{%- endif -%}

{%- comment -%}
  The required background image of the link to the current page may involve SCSS.
  To avoid page-dependent SCSS, all nav links initially have that background image.
  The following rule removes the image from the links to all parents, siblings,
  and children of the current page.
{%- endcomment %}

{% if activation_third_level_index -%}

{{ activation_collection_prefix }} > li > a,
{{ activation_collection_prefix }} > li > ul > li > a,
{{ activation_collection_prefix }} > li > ul > li > ul > li:not(:nth-child({{ activation_third_level_index }})) > a {
  background-image: none;
}

{%- elsif activation_second_level_index -%}

{{ activation_collection_prefix }} > li > a,
{{ activation_collection_prefix }} > li > ul > li:not(:nth-child({{ activation_second_level_index }})) > a,
{{ activation_collection_prefix }} > li > ul > li > ul > li > a {
  background-image: none;
}

{%- else -%}

{{ activation_collection_prefix }} > li:not(:nth-child({{ activation_first_level_index }})) > a,
{{ activation_collection_prefix }} > li > ul > li > a,
{{ activation_collection_prefix }} > li > ul > li > ul > li > a {
  background-image: none;
}

{%- endif %}

{%- comment -%}
  The following rule removes the image from the links to pages in other collections.
{%- endcomment %}

{{ activation_other_collection_prefix }} a,
.site-nav li.external a {
  background-image: none;
}

{%- comment -%}
  The following rule styles the link to the current page.
{%- endcomment %}

{{ activation_collection_prefix }} > li:nth-child({{ activation_first_level_index }})
{%- if activation_second_level_index %} > ul > li:nth-child({{ activation_second_level_index }})
{%- if activation_third_level_index %} > ul > li:nth-child({{ activation_third_level_index }})
{%- endif -%}
{%- endif %} > a {
  font-weight: 600;
  text-decoration: none;
}

{%- comment -%}
  The following rules unfold all collections, and display the links to any children
  of the current page.
  
  To avoid dependence on the SCSS variable nav-list-expander-right, the direction
  of the rotation of the expander icon is fixed, and corresponds to the appearance
  when nav-list-expander-right is true. This results in a minor visual difference
  between the appearance of active expander icons when JS is enabled/disabled and
  nav-list-expander-right is false, which seems unavoidable.
{%- endcomment %}

{%- if site.just_the_docs.collections %}
.site-nav > ul.nav-category-list > li > button svg,
{% endif -%}
{{ activation_collection_prefix }} > li:nth-child({{ activation_first_level_index }}) > button svg
{%- if activation_second_level_index -%},
{{ activation_collection_prefix }} > li:nth-child({{ activation_first_level_index }}) > ul > li:nth-child({{ activation_second_level_index }}) > button svg
{%- endif %} {
  transform: rotate(-90deg);
}

{%- if site.just_the_docs.collections %}
.site-nav > ul.nav-category-list > li.nav-list-item > ul.nav-list,
{% endif -%}
{{ activation_collection_prefix }} > li.nav-list-item:nth-child({{ activation_first_level_index }}) > ul.nav-list
{%- if activation_second_level_index %},
{{ activation_collection_prefix }} > li.nav-list-item:nth-child({{ activation_first_level_index }}) > ul.nav-list > li.nav-list-item:nth-child({{ activation_second_level_index }}) > ul.nav-list
{%- endif %} {
  display: block;
}

{%- endif -%}
{%- endif -%}
{%- endif -%}