A service that makes printing a PDF with pdfkit easier.

pdf_printer.rb

# Convert html to a PDF file.
class PdfPrinter
  include Virtus.model
  attribute :html, String
  attribute :file_name, String, default: ->(printer, attribute) { "#{SecureRandom.hex(20)}-#{DateTime.now.to_i}.pdf"}
  attribute :store_location, String, default: "/tmp"
  attribute :temp_css_location, String, default: "/tmp"
  attribute :wkhtmltopdf_parameters, Hash, default: {
          "--footer-right" => "[page]/[toPage]",
          "--footer-font-size" => 8
        }
  attribute :html_header, String, default: nil
  attribute :html_header_file_name, Object, default: ->(printer, attribute) { "#{SecureRandom.hex(20)}-#{DateTime.now.to_i}.html"}
  attribute :orientation, String, default: 'portrait'
  attribute :footer_center_text, String, default: ->(printer, attribute) { "Report - #{DateTime.now.strftime('%F')}"}

  def setup
    create_html_header_file if html_header.present?
  end

  def generate
    stylesheet = temp_stylesheet
    raise StandardError, "Not all parameters provided"  unless html && stylesheet
    pdf = PDFKit.new html
    # Add all stylesheets
    pdf.stylesheets << stylesheet
    # Pass parameters to pdf engine
    wkhtmltopdf_parameters.each do |key, value|
      pdf.options[key] = value
    end
    pdf.options["--footer-center"]    = footer_center_text
    if html_header_file_name.present?
      pdf.options["--header-html"]    = full_html_header_location
      pdf.options["--margin-top"] = 30
      pdf.options["--margin-bottom"] = 26
      pdf.options["--header-spacing"] = 5
      pdf.options["--footer-spacing"] = 5
    end
    pdf.options["--orientation"]   = orientation
    # Save PDF
    begin
      pdf.to_file full_file_location
    rescue => e
    end
    full_file_location
  end

  def full_file_location
    "#{store_location}/#{file_name}"
  end

  def full_html_header_location
    "#{store_location}/#{html_header_file_name}"
  end

  def css_file_name
    file_name.gsub(".pdf", ".css")
  end

  # To get stylesheets to work properly.
  def temp_stylesheet
    css = Rails.application.assets.find_asset('application_print.css').body
    temp_css_file = "#{temp_css_location}/#{css_file_name}"
    File.open(temp_css_file, 'w') { |file| file.write(css) }
    temp_css_file
  end

  def create_html_header_file
    File.open(full_html_header_location, "w") do |f|
      f.write html_header
    end
  end
end