require "set"

module Jekyll

  # REF: https://github.com/rpalo/personal-blog
  # Syncs the catpages with the cats in all of my posts
  Jekyll::Hooks.register :site, :post_read do |site|
    cats = Set.new(site.categories.keys)
    catpage_filenames = Dir.entries("./cats/")
    .grep(/\.md/)
    .map do |filename|
      filename.chomp(".md")
    end
    catpages = Set.new(catpage_filenames)
    cats_without_pages = cats - catpages
    pages_without_cats = catpages - cats
    puts "==== Create a catpage for any cat without a page.===="
    # Create a catpage for any cat without a page
    cats_without_pages.each do |cat|
      puts "Creating new catpage for: #{cat}"
      content = <<~HEREDOC
        ---
        layout: catpage
        cat: #{cat}
        permalink: /cats/#{cat}/
        ---
      HEREDOC
      File.open("cats/#{cat}.md", "w") do |f|
        f.write(content)
      end
    end



    # Delete the catpage for any page that doesn't have any cats
    pages_without_cats.each do |page|
      puts "Removing catpage for nonexistent cat: #{page}.  Ignore any Ruby errors reported."
      File.delete("src/cats/#{page}.md")
    end
  end
end