Tailwind CSS for Jekyll

tailwind_css.rb

# frozen_string_literal: true

require 'pathname'
require 'Open3'

module Jekyll
  class TailwindPlugin < Generator
    priority :normal

    def generate(site)
      setup(site)

      generate_css
      static_file = AlwaysWriteFile.new(site, site.source, "/assets/css", "tailwind.css")

      # Notify Jekyll that this file needs to be copied to the final site files
      site.static_files << static_file
    end

    def setup(site)
      config = site.config
      @tailwind_script = config.dig('tailwind', 'script')
      @tailwind_config = Pathname.new(config['source'] + '/tailwind.config.js')
      @tailwind_output = Pathname.new(config['source'] + '/assets/css/tailwind.css')

      tailwind_error "Please specify tailwind:script: in your config file" if @tailwind_script.nil?
      tailwind_error "Tailwindcss processor #{@tailwind_script} not found" unless Pathname.new(@tailwind_script).exist?
      tailwind_error "Tailwind config file #{@tailwind_config} missing" unless @tailwind_config.exist?
    end

    def generate_css
      base_file_path = '/tmp/twbase.css'
      File.write(base_file_path, TailwindBaseCSS)
      stdout, stderr, status = Open3.capture3(@tailwind_script,
        '--config', @tailwind_config.to_s,
        '--input', base_file_path,
        '--output', @tailwind_output.to_s)
      if status.exitstatus != 0
        tailwind_error(stderr)
      end
    end

    def tailwind_error(msg)
      Jekyll.logger.error "Tailwind:", msg
      exit 1
    end

    TailwindBaseCSS = 
    <<~ENDCSS
    @tailwind base;
    @tailwind components;
    @tailwind utilities;
    ENDCSS
      
  end

  class AlwaysWriteFile < StaticFile
    def modified?
      true
    end

    def write(dest)
      Jekyll.logger.info "Tailwind:", "Generated #{path}"
      super
    end
  end
end