Build MVP website from README (#338)

#### Summary

Adds the ability to convert the README.md to a website. This
productionizes #336 following
positive internal feedback on the direction.

The next steps will be to set up a GitHub workflow to publish the site
to GitHub Pages. We may also want to continue to polish the style.

#### Reasoning

A website will make the style guide more accessible. We chose to
generate the website from the README so that the existing workflow for
updating the style guide remains the same.


#### Testing

- [x] Run `bundle exec rake site:serve` locally and check the content at
http://localhost:4000
- [x] Verify that top badges and SPM command plugin sections are
filtered out of the site

| Top | Code block | Footer |
| --- | --- | --- |

|![image](https://github.com/user-attachments/assets/176cd61e-fb77-40ef-aa5c-8d25858eb883)
|
![image](https://github.com/user-attachments/assets/1c080b2a-2edd-4d7a-a674-ab1983cb61d4)
|
![image](https://github.com/user-attachments/assets/0f8bc71e-04ae-4719-97e3-7595635f6a18)
|


#### Please review

@airbnb/swift-styleguide-maintainers

Author: bachand

.github/workflows/main.yml

@@ -40,3 +40,16 @@ jobs:
           xcode: ${{ matrix.xcode }}
       - name: Run Unit Tests
         run: swift test
+
+  site-build:
+    name: Site Build
+    runs-on: macos-15
+    steps:
+      - uses: actions/checkout@v6
+      - uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+      - name: Build site
+        run: bundle exec rake site:build
+        env:
+          JEKYLL_ENV: production

.gitignore

@@ -1,4 +1,7 @@
 .build
 .swiftpm
 .DS_Store
-.vscode
+.vscode
+
+# The site generated by Jekyll.
+_site

Gemfile

@@ -1,3 +1,4 @@
-source 'https://rubygems.org' do
-  gem "rake", "~> 13.0.0"
-end
+source 'https://rubygems.org'
+
+gem "rake", "~> 13.0.0"
+gem "jekyll", "~> 4.4.1"

Gemfile.lock

@@ -1,17 +1,89 @@
-GEM
-  specs:
-
 GEM
   remote: https://rubygems.org/
   specs:
+    addressable (2.8.7)
+      public_suffix (>= 2.0.2, < 7.0)
+    base64 (0.3.0)
+    bigdecimal (3.3.1)
+    colorator (1.1.0)
+    concurrent-ruby (1.3.5)
+    csv (3.3.5)
+    em-websocket (0.5.3)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0)
+    eventmachine (1.2.7)
+    ffi (1.17.2)
+    ffi (1.17.2-arm64-darwin)
+    forwardable-extended (2.6.0)
+    google-protobuf (4.33.1)
+      bigdecimal
+      rake (>= 13)
+    google-protobuf (4.33.1-arm64-darwin)
+      bigdecimal
+      rake (>= 13)
+    http_parser.rb (0.8.0)
+    i18n (1.14.7)
+      concurrent-ruby (~> 1.0)
+    jekyll (4.4.1)
+      addressable (~> 2.4)
+      base64 (~> 0.2)
+      colorator (~> 1.0)
+      csv (~> 3.0)
+      em-websocket (~> 0.5)
+      i18n (~> 1.0)
+      jekyll-sass-converter (>= 2.0, < 4.0)
+      jekyll-watch (~> 2.0)
+      json (~> 2.6)
+      kramdown (~> 2.3, >= 2.3.1)
+      kramdown-parser-gfm (~> 1.0)
+      liquid (~> 4.0)
+      mercenary (~> 0.3, >= 0.3.6)
+      pathutil (~> 0.9)
+      rouge (>= 3.0, < 5.0)
+      safe_yaml (~> 1.0)
+      terminal-table (>= 1.8, < 4.0)
+      webrick (~> 1.7)
+    jekyll-sass-converter (3.1.0)
+      sass-embedded (~> 1.75)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    json (2.16.0)
+    kramdown (2.5.1)
+      rexml (>= 3.3.9)
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.4)
+    listen (3.9.0)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.4.0)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (6.0.2)
     rake (13.0.6)
+    rb-fsevent (0.11.2)
+    rb-inotify (0.11.1)
+      ffi (~> 1.0)
+    rexml (3.4.4)
+    rouge (4.6.1)
+    safe_yaml (1.0.5)
+    sass-embedded (1.94.2)
+      google-protobuf (~> 4.31)
+      rake (>= 13)
+    sass-embedded (1.94.2-arm64-darwin)
+      google-protobuf (~> 4.31)
+    terminal-table (3.0.2)
+      unicode-display_width (>= 1.1.1, < 3)
+    unicode-display_width (2.6.0)
+    webrick (1.9.1)
 
 PLATFORMS
   arm64-darwin-23
   ruby
 
 DEPENDENCIES
-  rake (~> 13.0.0)!
+  jekyll (~> 4.4.1)
+  rake (~> 13.0.0)
 
 BUNDLED WITH
    2.5.4

README.md

@@ -1056,6 +1056,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   ]
   ```
 
+  </details>
+
 * <a id='long-typealias'></a>(<a href='#long-typealias'>link</a>) [Long](https://github.com/airbnb/swift#column-width) type aliases of protocol compositions should wrap before the `=` and before each individual `&`. [![SwiftFormat: wrapArguments](https://img.shields.io/badge/SwiftFormat-wrapArguments-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#wrapArguments)
 
   <details>
@@ -1084,6 +1086,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
     & UniverseSimulatorServiceProviding
   ```
 
+  </details>
+
 * <a id='sort-typealiases'></a>(<a href='#sort-typealiases'>link</a>) **Sort protocol composition type aliases alphabetically.** [![SwiftFormat: sortTypealiases](https://img.shields.io/badge/SwiftFormat-sortTypealiases-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#sortTypealiases)
 
   <details>
@@ -1110,6 +1114,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
     & UniverseSimulatorServiceProviding
   ```
 
+  </details>
+
 * <a id='prefer-if-let-shorthand'></a>(<a href='#prefer-if-let-shorthand'>link</a>) Omit the right-hand side of the expression when unwrapping an optional property to a non-optional property with the same name. [![SwiftFormat: redundantOptionalBinding](https://img.shields.io/badge/SwiftFormat-redundantOptionalBinding-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#redundantOptionalBinding)
 
   <details>
@@ -1142,6 +1148,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   else { … }
   ```
 
+  </details>
+
 * <a id='else-on-same-line'></a>(<a href='#else-on-same-line'>link</a>) **Else statements should start on the same line as the previous condition's closing brace, unless the conditions are separated by a blank line or comments.** [![SwiftFormat: elseOnSameLine](https://img.shields.io/badge/SwiftFormat-elseOnSameLine-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#elseOnSameLine)
 
   <details>
@@ -1196,6 +1204,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   }
   ```
 
+  </details>
+
 * <a id='multi-line-conditions'></a>(<a href='#multi-line-conditions'>link</a>) **Multi-line conditional statements should break after the leading keyword.** Indent each individual statement by [2 spaces](https://github.com/airbnb/swift#spaces-over-tabs). [![SwiftFormat: wrapArguments](https://img.shields.io/badge/SwiftFormat-wrapArguments-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#wrapArguments)
 
   <details>
@@ -1609,6 +1619,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   }
   ```
 
+  </details>
+
 * <a id='indent-multiline-string-literals'></a>(<a href='#indent-multiline-string-literals'>link</a>) **Indent the body and closing triple-quote of multiline string literals**, unless the string literal begins on its own line in which case the string literal contents and closing triple-quote should have the same indentation as the opening triple-quote. [![SwiftFormat: indent](https://img.shields.io/badge/SwiftFormat-indent-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#indent)
 
   <details>
@@ -1779,6 +1791,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   }
   ```
 
+  </details>
+
 * <a id='no-spaces-around-function-parens'></a>(<a href='#no-spaces-around-parens'>link</a>) For function calls and declarations, there should be no spaces before or inside the parentheses of the argument list. [![SwiftFormat: spaceInsideParens](https://img.shields.io/badge/SwiftFormat-spaceInsideParens-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#spaceInsideParens) [![SwiftFormat: spaceAroundParens](https://img.shields.io/badge/SwiftFormat-spaceAroundParens-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#spaceAroundParens)
 
   <details>
@@ -3010,6 +3024,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   }
   ```
 
+  </details>
+
 * <a id='avoid-global-functions'></a>(<a href='#avoid-global-functions'>link</a>) **Avoid global functions whenever possible.** Prefer methods within type definitions.
 
   <details>
@@ -4694,6 +4710,8 @@ _You can enable the following settings in Xcode by running [this script](resourc
   }
   ```
 
+  </details>
+
 * <a id='prefer-throwing-tests'></a>(<a href='#prefer-throwing-tests'>link</a>) **Prefer throwing tests to `try!`**. `try!` will crash your test suite like a force-unwrapped optional. XCTest and Swift Testing support throwing test methods, so use that instead. [![SwiftFormat: noForceTryInTests](https://img.shields.io/badge/SwiftFormat-noForceTryInTests-7B0051.svg)](https://github.com/nicklockwood/SwiftFormat/blob/main/Rules.md#noForceTryInTests)
 
   <details>

Rakefile

@@ -30,26 +30,55 @@ namespace :update do
     temp_dir = Dir.mktmpdir
     artifact_bundle_url = "https://github.com/calda/SwiftFormat-nightly/releases/download/#{latest_version_number}/swiftformat.artifactbundle.zip"
     artifact_bundle_zip_path = "#{temp_dir}/swiftformat.artifactbundle.zip"
-    
+
     sh "curl #{artifact_bundle_url} -L --output #{artifact_bundle_zip_path}"
     checksum = `swift package compute-checksum #{artifact_bundle_zip_path}`
 
     # Update the Package.swift file to reference this version
     package_manifest_path = 'Package.swift'
     package_manifest_content = File.read(package_manifest_path)
-    
+
     updated_swift_format_reference = <<-EOS
     .binaryTarget(
       name: "swiftformat",
       url: "https://github.com/calda/SwiftFormat-nightly/releases/download/#{latest_version_number}/SwiftFormat.artifactbundle.zip",
       checksum: "#{checksum.strip}"
     ),
     EOS
-    
+
     regex = /[ ]*.binaryTarget\([\S\s]*name: "swiftformat"[\S\s]*?\),\s/
     updated_package_manifest = package_manifest_content.gsub(regex, updated_swift_format_reference)
     File.open(package_manifest_path, "w") { |file| file.puts updated_package_manifest }
-    
+
     puts "Updated Package.swift to reference SwiftFormat #{latest_version_number}"
   end
 end
+
+namespace :site do
+  desc 'Prints the README content used to build the site'
+  task :filter_readme do
+    require_relative 'site/site_content'
+    puts SiteContent.new.filter_readme
+  end
+
+  desc 'Prepares index.md and syntax highlighting assets'
+  task :prepare do
+    require_relative 'site/site_content'
+    puts '📋 Generating index.md from README.md with frontmatter...'
+    SiteContent.new.write_index
+    puts '🎨 Generating syntax highlighting CSS...'
+    SiteContent.new.generate_syntax_css
+  end
+
+  desc 'Builds the static site into _site/'
+  task build: :prepare do
+    env = { 'JEKYLL_ENV' => ENV.fetch('JEKYLL_ENV', 'production') }
+    sh env, 'bundle exec jekyll build --source site/src'
+  end
+
+  desc 'Serves the site to support previewing its content during development'
+  task serve: :prepare do
+    env = { 'JEKYLL_ENV' => 'development' }
+    sh env, 'bundle exec jekyll serve --source site/src'
+  end
+end

site/.gitignore

@@ -0,0 +1,3 @@
+# These site source files are generated.
+src/index.md
+src/assets/css/syntax.css

site/README.md

@@ -0,0 +1,11 @@
+# Website
+
+## Local development
+
+To start the local development server, run the following command:
+
+```bash
+bundle exec rake site:serve
+```
+
+Once the server is running, open [http://localhost:4000](http://localhost:4000) in your browser to preview the site.

site/site_content.rb

@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+require 'open3'
+
+class SiteContent
+  attr_reader :readme_path, :index_path, :syntax_css_path
+
+  def initialize()
+    site_dir = File.expand_path('src', __dir__)
+    @readme_path = File.expand_path('../README.md', __dir__)
+    @index_path = File.join(site_dir, 'index.md')
+    @syntax_css_path = File.join(site_dir, 'assets/css/syntax.css')
+  end
+
+  def filter_readme
+    (filter_readme_lines + ['']).join("\n")
+  end
+
+  # Write index.md file.
+  def write_index
+    File.write(index_path, generate_front_matter + filter_readme)
+  end
+
+  # Write syntax.css file.
+  def generate_syntax_css
+    stdout, stderr, status = Open3.capture3('bundle', 'exec', 'rougify', 'style', 'github.light')
+    raise "rougify failed:\n#{stderr}" unless status.success?
+
+    File.write(syntax_css_path, stdout)
+  end
+
+  private
+
+  def generate_front_matter
+    <<~FRONT
+      ---
+      layout: default
+      ---
+
+    FRONT
+  end
+
+  def filter_readme_lines
+    lines = File.readlines(readme_path, chomp: true)
+    filtered = []
+    skip_plugin_section = false
+    skip_amendments_section = false
+
+    lines.each do |line|
+      # Exclude the SPM command plugin section from the site.
+      if line.start_with?('## Swift Package Manager command plugin')
+        skip_plugin_section = true
+        next
+      elsif skip_plugin_section
+        skip_plugin_section = false if line.start_with?('## ')
+        next if skip_plugin_section
+      end
+
+      if line.start_with?('## Amendments')
+        skip_amendments_section = true
+        next
+      elsif skip_amendments_section
+        skip_amendments_section = false if line.start_with?('** ')
+        next if skip_amendments_section
+      end
+
+      # Exclude the badges from the site.
+      stripped = line.strip
+      next if stripped.start_with?('[![](') && stripped.include?('swiftpackageindex.com')
+
+      filtered << line.rstrip
+    end
+
+    filtered
+  end
+end

site/src/_config.yml

@@ -0,0 +1,6 @@
+title: Airbnb Swift Style Guide
+github_url: https://github.com/airbnb/swift
+markdown: kramdown
+kramdown:
+  input: GFM
+  parse_block_html: true