module Nokogiri
  module XML
    # Patch to add class?
    class Node
      def class?(*classes)
        present = false
        if self.attribute('class')
          present = true
          classes.each do |klass|
            present &&= self['class'].include? klass
          end
        end
        present
      end
    end
  end
end

# https://stackoverflow.com/a/42533209/368328
def command?(name)
  [name,
   *ENV['PATH'].split(File::PATH_SEPARATOR)
               .map { |p| File.join(p, name) }]
    .find { |f| File.executable?(f) }
end

def commands?(commands)
  commands.map { |c| command? c }
end

def format_match(format)
  [:all, format].include? format
end

def gen_epub(name, _format)
  if command?('pandoc') && format_match(:epub)
    # Convert it to epub
    `pandoc -S -o books/#{name}.epub --epub-metadata=metadata/#{name}.xml --epub-cover-image=covers/#{name}.jpg books/#{name}.html`
    puts '[epub] Generated EPUB file'
  else
    puts "[error] Can't generate EPUB without pandoc"
  end
end

def gen_mobi(name, _format)
  if command?('ebook-convert') && format_match(:mobi)
    # Convert epub to a mobi
    `ebook-convert books/#{name}.epub books/#{name}.mobi`
    puts '[mobi] Generated MOBI file'
  else
    puts "[error] Can't generate MOBI without ebook-convert"
  end
end

def gen_pdf(name, _format)
  if commands?(%w[pandoc convert wkhtmltopdf pdftk]) && format_match(:pdf)
    # Generate PDF as well
    # First, lets make a better css version of the html
    `pandoc books/#{name}.html -s -c ../style.css  -o books/#{name}_pdf.html`
    puts '[pdf] Generated html for pdf'

    # Print the pdf_html file to pdf
    `wkhtmltopdf books/#{name}_pdf.html books/#{name}-nocover.pdf`
    puts '[pdf] Generated PDF without cover'

    # Join the cover and pdf together
    `pdftk covers/#{name}.pdf books/#{name}-nocover.pdf cat output books/#{name}.pdf`
    puts '[pdf] Generated PDF file'
  else
    puts '[error] Please check README for PDF dependencies'
  end
end

def generate(name, _format = :all)
  gen_epub(name, _format)
  gen_mobi(name, _format)
  gen_pdf(name, _format)
end