From ca6336c7157541d55d6672687f951dd5c065c2a9 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 14 Jun 2019 16:45:59 -0400
Subject: [PATCH] user guide: add page navigation links

---
 rb/assets/user_guide.html.erb | 13 +++++++++++
 rb/gen_user_guide.rb          | 41 +++++++++++++++++++++++++++++------
 2 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/rb/assets/user_guide.html.erb b/rb/assets/user_guide.html.erb
index c88ec3a..380d18b 100644
--- a/rb/assets/user_guide.html.erb
+++ b/rb/assets/user_guide.html.erb
@@ -28,6 +28,19 @@
       a {
         text-decoration: none;
       }
+      #page_nav {
+        margin-top: 2em;
+      }
+      #page_nav_prev {
+        float: left;
+      }
+      #page_nav_toc {
+        text-align: center;
+      }
+      #page_nav_next {
+        float: right;
+        text-align: right;
+      }
       .code {
         padding-left: 2ex;
       }
diff --git a/rb/gen_user_guide.rb b/rb/gen_user_guide.rb
index 3b3e872..1e5d50c 100644
--- a/rb/gen_user_guide.rb
+++ b/rb/gen_user_guide.rb
@@ -79,15 +79,15 @@ class Generator
     @markdown_renderer = Redcarpet::Markdown.new(renderer)
     changelog = @markdown_renderer.render(File.read("CHANGELOG.md"))
 
-    pages = [Page.new("toc", "Table of Contents", render_toc)]
+    @pages = [Page.new("toc", "Table of Contents", render_toc)]
     @sections.each do |section|
-      unless pages.last.name == section.page
-        pages << Page.new(section.page, section.title)
+      unless @pages.last.name == section.page
+        @pages << Page.new(section.page, section.title)
       end
-      pages.last.contents += render_section(section)
+      @pages.last.contents += render_section(section)
     end
 
-    pages.each do |page|
+    @pages.each do |page|
       page.contents.gsub!("${changelog}", changelog)
       page.contents.gsub!(%r{\$\{#(.+?)\}}) do |match|
         section_name = $1
@@ -100,9 +100,10 @@ class Generator
     erb = ERB.new(template, nil, "<>")
 
     if multi_page
-      pages.each do |page|
+      @pages.each_with_index do |page, page_index|
         subpage_title = " - #{page.title}"
         content = page.contents
+        content += render_page_links(page_index)
         html_result = erb.result(binding.clone)
         File.open(File.join(output_file, "#{page.name}.html"), "w") do |fh|
           fh.write(html_result)
@@ -110,7 +111,7 @@ class Generator
       end
     else
       subpage_title = ""
-      content = pages.reduce("") do |result, page|
+      content = @pages.reduce("") do |result, page|
         result + page.contents
       end
       html_result = erb.result(binding.clone)
@@ -120,6 +121,32 @@ class Generator
     end
   end
 
+  def render_page_links(page_index)
+    page_nav_prev =
+      if page_index > 1
+        %[<a href="#{@pages[page_index - 1].name}.html">&laquo; Prev<br/>#{@pages[page_index - 1].title}</a>]
+      else
+        ""
+      end
+    page_nav_toc =
+      if page_index > 0
+        %[<a href="toc.html">Table of Contents</a>]
+      else
+        ""
+      end
+    page_nav_next =
+      if page_index < @pages.size - 1
+        %[<a href="#{@pages[page_index + 1].name}.html">Next &raquo<br/>#{@pages[page_index + 1].title}</a>]
+      else
+        ""
+      end
+    %[<div id="page_nav">] + \
+    %[<div id="page_nav_prev">#{page_nav_prev}</div>] + \
+    %[<div id="page_nav_next">#{page_nav_next}</div>] + \
+    %[<div id="page_nav_toc">#{page_nav_toc}</div>] + \
+    %[</div>]
+  end
+
   def render_toc
     toc_content = %[<h1>Table of Contents</h1>\n]
     @sections.each do |section|