From 18608c867a6cbe7880ea0273c463d4be93f2cc9f Mon Sep 17 00:00:00 2001
From: Harald Eilertsen <haraldei@anduin.net>
Date: Mon, 28 Aug 2017 22:23:44 +0200
Subject: Fix prev/next links for posts.

Now points to prev/next post in same language as the current post.
---
 blog/_layouts/post.html    | 12 +++++-----
 blog/_plugins/prev_next.rb | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 6 deletions(-)
 create mode 100644 blog/_plugins/prev_next.rb

diff --git a/blog/_layouts/post.html b/blog/_layouts/post.html
index 8a3cccb..f4f2a59 100644
--- a/blog/_layouts/post.html
+++ b/blog/_layouts/post.html
@@ -13,11 +13,11 @@ layout: default
     {{ content }}
   </section>
   <footer>
-    {% if page.previous %}
-      <div class="prev-post"><a href="{{ page.previous.url | prepend: site.baseurl }}">{{ page.previous.title }}</a></div>
-    {% endif %}
-    {% if page.next %}
-      <div class="next-post"><a href="{{ page.next.url | prepend: site.baseurl }}">{{ page.next.title }}</a></div>
-    {% endif %}
+    <div class="prev-post">
+      {% link_to_prev_page Forrige: %}
+    </div>
+    <div class="next-post">
+      {% link_to_next_page Neste: %}
+    </div>
   </footer>
 </article>
diff --git a/blog/_plugins/prev_next.rb b/blog/_plugins/prev_next.rb
new file mode 100644
index 0000000..7e9c983
--- /dev/null
+++ b/blog/_plugins/prev_next.rb
@@ -0,0 +1,57 @@
+require 'pry-byebug'
+
+module Jekyll
+  class PrevNextTag < Liquid::Tag
+
+    def initialize(tag_name, text, tokens)
+      super
+      @tag = tag_name
+      @text = text
+    end
+
+    def render(context)
+      page = context['page']
+      other_page = case @tag
+      when "link_to_prev_page" then find_prev(page)
+      when "link_to_next_page" then find_next(page)
+      else nil
+      end
+
+      if other_page
+        %Q{<a href="#{other_page['url']}">#{@text} #{other_page['title']}</a>}
+      else
+        ""
+      end
+    end
+
+    private
+
+    def find_prev(obj)
+      n = obj.previous
+      loop do
+        if n && n['lang'] != obj['lang']
+          n = n.previous
+        else
+          break
+        end
+      end
+      return n
+    end
+
+    def find_next(obj)
+      n = obj.next
+      loop do
+        if n && n['lang'] != obj['lang']
+          n = n.next
+        else
+          break
+        end
+      end
+      return n
+    end
+
+  end
+end
+
+Liquid::Template.register_tag('link_to_next_page', Jekyll::PrevNextTag)
+Liquid::Template.register_tag('link_to_prev_page', Jekyll::PrevNextTag)
-- 
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