1 files changed, 57 insertions, 0 deletions
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)