Add skin_manager plugins

_includes/footer/custom.html

@@ -1,3 +1,3 @@
 <!-- start custom footer snippets -->
 
-<!-- end custom footer snippets -->
+<!-- end custom footer snippets -->

_includes/scripts.html

@@ -0,0 +1,55 @@
+{% if site.footer_scripts %}
+  {% for script in site.footer_scripts %}
+    <script src="{{ script | relative_url }}"></script>
+  {% endfor %}
+{% else %}
+  <script src="{{ '/assets/js/main.min.js' | relative_url }}"></script>
+{% endif %}
+
+{% if site.search == true or page.layout == "search" %}
+  {%- assign search_provider = site.search_provider | default: "lunr" -%}
+  {%- case search_provider -%}
+    {%- when "lunr" -%}
+      {% include_cached search/lunr-search-scripts.html %}
+    {%- when "google" -%}
+      {% include_cached search/google-search-scripts.html %}
+    {%- when "algolia" -%}
+      {% include_cached search/algolia-search-scripts.html %}
+  {%- endcase -%}
+{% endif %}
+
+{% include analytics.html %}
+{% include /comments-providers/scripts.html %}
+
+{% if site.after_footer_scripts %}
+  {% for script in site.after_footer_scripts %}
+    <script src="{{ script | relative_url }}"></script>
+  {% endfor %}
+{% endif %}
+
+<div class="sub-footer">
+  <div id="skin-switch-container">
+    Page rendered with the <select id="skin-switch" onchange="changeSkin()">
+      {%- for skin in page.available_skins %}
+      {% if skin == 'default' -%}
+      <option value="_default.css">default</option>
+      {%- else -%}
+      <option value="{{ skin }}.css">{{ skin }}</option>
+      {%- endif %}
+      {%- endfor %}
+    </select> skin of Minimal-Mistakes theme.
+  </div>
+</div>
+
+<script>
+  document.getElementById("skin-switch-container").style.display = "block";
+  var metaTag = document.getElementById("stylesheet");
+  var SSHref = metaTag.href;
+  var SSName = (SSHref.substring(SSHref.lastIndexOf('/') + 1));
+
+  document.getElementById("skin-switch").value = SSName;
+
+  function changeSkin() {
+    metaTag.href = SSHref.replace(SSName, event.target.value);
+  }
+</script>

_plugins/skin_manager.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module SkinManager
+  class << self
+    attr_accessor :available_skins
+  end
+
+  Jekyll::Hooks.register :site, :post_read do |site|
+    skins_dir = site.in_theme_dir("_sass", "minimal-mistakes", "skins")
+    SkinManager.available_skins = Dir["#{skins_dir}/*.scss"].map { |i| File.basename(i, ".scss") }
+  end
+
+  Jekyll::Hooks.register [:pages, :documents], :pre_render do |doc, payload|
+    payload["page"]["available_skins"] = SkinManager.available_skins
+  end
+
+  class SkinPage < Jekyll::PageWithoutAFile
+    def initialize(site, skin_name)
+      super(site, site.source, "assets/css", "#{skin_name}.scss")
+    end
+  end
+
+  class StyleSheetGenerator < Jekyll::Generator
+    def generate(site)
+      SkinManager.available_skins.each do |skin_name|
+        site.pages << SkinPage.new(site, skin_name).tap do |page|
+          page.data["skin_name"] = skin_name
+          page.content = <<~SCSS
+          @import 
+            "minimal-mistakes/skins/{{ page.skin_name }}",
+            "minimal-mistakes";
+          SCSS
+        end
+      end
+    end
+  end
+end