require 'zip'
require 'nokogiri'
require 'combine_pdf'

module Letters
  def self.apply_template(io, params)
    Zip::OutputStream.write_buffer do |out|
      Zip::File.open(io) do |zip|
        zip.each do |entry|
          out.put_next_entry(entry.name)
          if entry.name == "content.xml"
            out.write apply_template_xml(entry.get_input_stream.read, params)
          elsif !entry.directory?
            out.write entry.get_input_stream.read
          end
        end
      end
    end
  end

  def self.apply_template_xml(xml, params)
    doc = Nokogiri::XML(xml)

    doc.xpath("//*[contains(text(), 'DISPLAY_NAME')]").each do |node|
      node.content = node.content.gsub("DISPLAY_NAME", params["DISPLAY_NAME"])
    end

    address_lines = params['ADDRESS'].split("\n")
    doc.xpath("//*[contains(text(), 'ADDRESS')]").each do |node|
      newnodes = [node] + address_lines[1..].map do |line|
        node.clone.tap do |c|
          c.content = c.content.gsub("ADDRESS", line)
        end
      end
      node.content = node.content.gsub("ADDRESS", address_lines.first)

      newnodes.each_cons(2) do |p, n|
        p.add_next_sibling(n)
      end
    end

    doc.to_xml(save_with: 0)
  end

  def self.generate(template, members)
    Dir.mktmpdir do |directory|
      members.each do |member|
        odt = apply_template(template, {
          "DISPLAY_NAME" => member.display_name,
          "ADDRESS" => member.address,
        })

        File.open("#{directory}/#{member.number}.odt", "wb") { |out| out.write(odt.string) }
      end

      `libreoffice --convert-to pdf --outdir #{directory} #{directory}/*.odt`

      pdf = CombinePDF.new

      Dir["#{directory}/*.pdf"].each do |file|
        pdf << CombinePDF.load(file)
      end

      pdf.to_pdf
    end
  end
end