Allow for overriding only specific Mustache templates/partials. (#1719)

* Allow for overriding only specific templates/partials. Resolves  #1450.

README.md

@@ -126,7 +126,7 @@ Gollum comes with the following command line options:
 | --no-display-metadata | none  | Do not render metadata tables in pages. |
 | --user-icons      | [MODE]    | Tell Gollum to use specific user icons for history view. Can be set to `gravatar`, `identicon` or `none`. Default: `none`. |
 | --mathjax-config  | [FILE]    | Specify path to a custom MathJax configuration. If not specified, uses the `mathjax.config.js` file from repository root. |
-| --template-dir    | [PATH]    | Specify custom mustache template directory. |
+| --template-dir    | [PATH]    | Specify custom mustache template directory. Only overrides templates that exist in this directory. |
 | --template-page   | none      | Use _Template in root as a template for new pages. Must be committed. |
 | --emoji           | none      | Parse and interpret emoji tags (e.g. `:heart:`) except when the leading colon is backslashed (e.g. `\:heart:`). |
 | --lenient-tag-lookup | none | Internal links resolve case-insensitively, will treat spaces as hyphens, and will match the first page found with a certain filename, anywhere in the repository. Provides compatibility with Gollum 4.x. |

bin/gollum

@@ -149,7 +149,7 @@ MSG
     'Can be set to \'gravatar\' or \'identicon\'. Default: standard avatar.') do |mode|
     wiki_options[:user_icons] = mode.to_s
   end
-  opts.on('--template-dir [PATH]', 'Specify custom mustache template directory.') do |path|
+  opts.on('--template-dir [PATH]', 'Specify custom mustache template directory. Only overrides templates that exist in this directory.') do |path|
     wiki_options[:template_dir] = path
   end
   opts.on('--template-page', 'Use _Template.{ext} as a template for new pages.') do
@@ -271,7 +271,6 @@ else
   Precious::App.set(:environment, ENV.fetch('RACK_ENV', :production).to_sym)
   Precious::App.set(:gollum_path, gollum_path)
   Precious::App.set(:wiki_options, wiki_options)
-  Precious::App.settings.mustache[:templates] = wiki_options[:template_dir] if wiki_options[:template_dir]
 
   if cfg = options[:config]
     # If the path begins with a '/' it will be considered an absolute path,

lib/gollum/app.rb

@@ -22,6 +22,7 @@ require 'gollum/views/has_page'
 require 'gollum/views/has_user_icons'
 require 'gollum/views/pagination'
 require 'gollum/views/rss.rb'
+require 'gollum/views/template_cascade'
 
 require File.expand_path '../helpers', __FILE__
 
@@ -110,7 +111,11 @@ module Precious
       @wiki_title = settings.wiki_options.fetch(:title, 'Gollum Wiki')
 
       forbid unless @allow_editing || request.request_method == 'GET'
-      Precious::App.set(:mustache, {:templates => settings.wiki_options[:template_dir]}) if settings.wiki_options[:template_dir]
+
+      if settings.wiki_options[:template_dir]
+        Precious::Views::Layout.extend Precious::Views::TemplateCascade
+        Precious::Views::Layout.template_priority_path = settings.wiki_options[:template_dir]
+      end
 
       @base_url = url('/', false).chomp('/').force_encoding('utf-8')
       @page_dir = settings.wiki_options[:page_file_dir].to_s

lib/gollum/views/template_cascade.rb

@@ -0,0 +1,36 @@
+module Precious
+  module Views
+    module TemplateCascade
+      def template_priority_path
+        @@template_priority_path
+      end
+
+      def template_priority_path=(path)
+        @@template_priority_path = File.expand_path(path)
+        @template = nil
+      end
+
+      def first_path_available(name)
+        priority = File.join(template_priority_path, "#{name}.#{template_extension}")
+        default = File.join(template_path, "#{name}.#{template_extension}")
+        File.exists?(priority) ? priority : default
+      end
+
+      # Method should track lib/mustache/settings.rb from Mustache project.
+      def template_file
+        @template_file || first_path_available(template_name)
+      end
+
+      # Method should track lib/mustache.rb from Mustache project.
+      def partial(name)
+        path = first_path_available(name)
+        begin
+          File.read(path)
+        rescue
+          raise if raise_on_context_miss?
+          ""
+        end
+      end
+    end
+  end
+end

test/examples/template_cascade/navbar.mustache

@@ -0,0 +1,8 @@
+<nav>
+  <div style="background-color: red;">NAVBAR_OVERRIDE</div>
+
+  <p>Still include an original partial to ensure the fallback works even when nested from an overriden partial:</p>
+  <div>
+    {{>mobilenav}}
+  </div>
+</nav>

test/examples/template_cascade/page.mustache

@@ -0,0 +1,12 @@
+<div id="wiki-wrapper" class="page">
+
+<p>Include an overridden partial:</p>
+<div id="head">
+	{{#navbar?}}{{>navbar}}{{/navbar?}}
+</div>
+
+<div style="background-color: red;">PAGE_OVERRIDE</div>
+
+{{>wiki_content}}
+
+</div>

test/test_template_cascade.rb

@@ -0,0 +1,43 @@
+# ~*~ encoding: utf-8 ~*~
+require File.expand_path(File.join(File.dirname(__FILE__), 'helper'))
+
+class TestTemplateCascade < Minitest::Unit::TestCase
+  include Rack::Test::Methods
+
+  def setup
+    @path = cloned_testpath('examples/lotr.git')
+    Precious::App.set(:gollum_path, @path)
+    Precious::App.set(:wiki_options, {template_dir: testpath('examples/template_cascade')})
+    @wiki = Gollum::Wiki.new(@path)
+  end
+
+  def teardown
+    FileUtils.rm_rf(@path)
+  end
+
+  def app
+    Precious::App
+  end
+
+  def test_overridden_page_template_is_used
+    get '/Home'
+
+    assert last_response.body.include?('PAGE_OVERRIDE')
+  end
+
+  def test_overridden_navbar_partial_is_used
+    get '/Home'
+
+    assert last_response.body.include?('NAVBAR_OVERRIDE')
+  end
+
+  def test_overridden_templates_are_ignore_without_template_dir_set
+    Precious::App.set(:wiki_options, {template_dir: nil})
+
+    get '/Home'
+    assert_equal '/Home', last_request.fullpath
+    assert last_response.ok?
+    assert_no_match /PAGE_OVERRIDE/, last_response.body
+    assert_no_match /NAVBAR_OVERRIDE/, last_response.body
+  end
+end