class PDF

  PATH     = "#{Rails.root}/pdfs"
  TMP_PATH = "#{Rails.root}/tmp/pdfs"

  DEFAULT_OPTIONS = {
    'footer-center'       => 'Page [page]',
    'footer-left'         => "Mealr.net",
    'footer-right'        => "Copyright #{Time.now.strftime('%Y')}",
    'margin-top'          => '0.75in',
    'margin-bottom'       => '0.5in',
    'margin-right'        => '0.5in',
    'margin-left'         => '0.5in',
    'page-size'           => 'Letter',
    'header-spacing'      => '5',
    'encoding'            => 'UTF-8'
    #'load-error-handling' => 'ignore' # @todo, upgrade wkhtmltopdf on mealr server
  }

  EXECUTABLE = '/usr/bin/env wkhtmltopdf'

  attr_accessor :options, :source, :filename, :header, :stylesheets, :xmlpath, :pdfpath, :headerpath

  def initialize(id, source, filename = nil, options = {})
    @options = DEFAULT_OPTIONS
    @options.merge options
    @source = source
    @id = id
    @filename = filename ? filename : @id

    @xmlpath    = "#{TMP_PATH}/#{@id}.xml"
    @headerpath = "#{TMP_PATH}/#{@id}-header.xml"
    @pdfpath    = "#{PATH}/#{@filename}.pdf"

    create_pdf_dir
  end

  def to_pdf
    add_stylesheets
    check_for_custom_header
    save_source_as_xml
    generate_pdf
  end

  protected

  def create_pdf_dir
    Dir.mkdir("#{PATH}") unless Dir.exists?("#{PATH}")
    Dir.mkdir("#{TMP_PATH}") unless Dir.exists?("#{TMP_PATH}")
  end

  def save_source_as_xml
    f = File.new(@xmlpath, "w")
    f.write @source
    f.close
  end

  def add_stylesheets
    if @stylesheets.is_a? Array
      @stylesheets.each do |stylesheet|
        add_stylesheet stylesheet
      end
    elsif @stylesheets.is_a? String
      add_stylesheet stylesheet
    end
  end

  def add_stylesheet(path)
    @source = @source.gsub(/(<\/head>)/, "<style>#{File.read(path)}</style>" +'\1')
  end

  def check_for_custom_header
    f = File.new(@headerpath, "w")
    f.write @header
    f.close

    @options['header-html'] = @headerpath
  end

  def generate_pdf
    options = @options.map {|k,v| "--#{k} \"#{v}\"" }
    command = "#{EXECUTABLE} #{options.join(' ')} --quiet #{@xmlpath} #{@pdfpath}"
    system(command)
  end

end