From a6f0452115dd57dfbecfa42e4851b663c0979edc Mon Sep 17 00:00:00 2001
From: Peter Mosses <18308236+pdmosses@users.noreply.github.com>
Date: Sat, 23 Jul 2022 06:56:23 +0200
Subject: [PATCH] Fix nav disambiguation issues involving grandparents (#890)

- add an extra filter to children-list to fix #854
- strengthen condition for assignment to first_level_url

Tested with Jekyll 3.9.2 and 4.2.2

Note: Jekyll 3.9.2 doesn't support `| where: "grand_parent:  nil"`
---
 _includes/nav.html | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/_includes/nav.html b/_includes/nav.html
index 3881008..0d2e6ef 100644
--- a/_includes/nav.html
+++ b/_includes/nav.html
@@ -67,9 +67,9 @@
         <a href="{{ node.url | relative_url }}" class="nav-list-link{% if page.url == node.url %} active{% endif %}">{{ node.title }}</a>
         {%- if node.has_children -%}
           {%- if node.child_nav_order == 'desc' -%}
-            {%- assign children_list = pages_list | where: "parent", node.title | reverse -%}
+            {%- assign children_list = pages_list | where: "parent", node.title | where_exp:"item", "item.grand_parent == nil" | reverse -%}
           {%- else -%}
-            {%- assign children_list = pages_list | where: "parent", node.title -%}
+            {%- assign children_list = pages_list | where: "parent", node.title | where_exp:"item", "item.grand_parent == nil" -%}
           {%- endif -%}
           <ul class="nav-list ">
           {%- for child in children_list -%}
@@ -119,7 +119,7 @@
 
   {%- for node in pages_list -%}
     {%- if node.parent == nil -%}
-      {%- if page.parent == node.title or page.grand_parent == node.title -%}
+      {%- if page.grand_parent == node.title or page.parent == node.title and page.grand_parent == nil -%}
         {%- assign first_level_url = node.url | relative_url -%}
       {%- endif -%}
       {%- if node.has_children -%}