Add 404 and sitemap handler (#1181)

docs/404.html

@@ -0,0 +1,68 @@
+---
+layout: default
+title: 404 - Page not found
+permalink: /404.html
+nav_exclude: true
+search_exclude: true
+---
+
+<style>
+  .error-404 {
+    text-align: center;
+    padding: 4rem 2rem;
+  }
+  .error-404 h1 {
+    font-size: 6rem;
+    color: #f49541;
+    margin-bottom: 1rem;
+  }
+  .error-404 h2 {
+    font-size: 2rem;
+    margin-bottom: 1rem;
+    color: #f8f9fa;
+  }
+  .error-404 p {
+    font-size: 1.2rem;
+    margin-bottom: 2rem;
+    color: #d1d5db;
+  }
+  .error-404 .btn {
+    display: inline-block;
+    padding: 0.75rem 1.5rem;
+    background-color: #d68338;
+    color: white;
+    text-decoration: none;
+    border-radius: 4px;
+    transition: background-color 0.2s;
+  }
+  .error-404 .btn:hover {
+    background-color: #f49541;
+  }
+  .error-404 .links {
+    margin-top: 2rem;
+  }
+  .error-404 .links a {
+    margin: 0 1rem;
+    color: #f49541;
+    text-decoration: underline;
+  }
+  .error-404 .links a:hover {
+    color: #ffd5a8;
+  }
+</style>
+
+<div class="error-404">
+  <h1>404</h1>
+  <h2>Page Not Found</h2>
+  <p>The page you're looking for doesn't exist or may have been moved.</p>
+  <p>This could happen if the documentation structure has been reorganized or the page has been renamed.</p>
+  
+  <a href="{{ '/' | relative_url }}" class="btn">Go to Home</a>
+  
+  <div class="links">
+    <p>Or try these helpful links:</p>
+    <a href="{{ '/installation/' | relative_url }}">Installation Guide</a>
+    <a href="{{ '/browser-extension/' | relative_url }}">Browser Extension</a>
+    <a href="{{ '/mobile-app/' | relative_url }}">Mobile App</a>
+  </div>
+</div>

docs/Gemfile

@@ -6,3 +6,7 @@ gem "just-the-docs"
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
 gem "github-pages", group: :jekyll_plugins
+
+group :jekyll_plugins do
+  gem "jekyll-sitemap"
+end

docs/Gemfile.lock

@@ -284,6 +284,7 @@ PLATFORMS
 
 DEPENDENCIES
   github-pages
+  jekyll-sitemap
   just-the-docs
 
 BUNDLED WITH

docs/_config.yml

@@ -41,3 +41,15 @@ callouts:
   important:
     title: Important
     color: yellow
+
+# 404 page
+defaults:
+  - scope:
+      path: "404.html"
+    values:
+      sitemap: false
+
+# Sitemap settings
+url: "https://docs.aliasvault.net"
+plugins:
+  - jekyll-sitemap

docs/_plugins/404_server.rb

@@ -0,0 +1,44 @@
+require 'webrick'
+
+module Jekyll
+  class FourOhFourPage < StaticFile
+    def write(dest)
+      true
+    end
+  end
+
+  class FourOhFourGenerator < Generator
+    priority :low
+
+    def generate(site)
+      site.static_files << FourOhFourPage.new(site, site.dest, '/', '404.html')
+    end
+  end
+end
+
+# Override WEBrick to serve 404.html for missing files
+if defined?(WEBrick)
+  module WEBrick
+    class HTTPServlet::FileHandler
+      alias_method :do_GET_original, :do_GET
+
+      def do_GET(req, res)
+        do_GET_original(req, res)
+      rescue HTTPStatus::NotFound => ex
+        return_404_page(req, res)
+      rescue => ex
+        raise ex
+      end
+
+      def return_404_page(req, res)
+        path = File.join(@config[:DocumentRoot], '404.html')
+        if File.exist?(path)
+          res.body = File.read(path)
+          res['content-type'] = 'text/html'
+        else
+          raise HTTPStatus::NotFound
+        end
+      end
+    end
+  end
+end