How to replace substitutions in docs file

legal_paper.rb

class LegalPaper
  attr_reader :docx_path
  
  def initialize(docx_path)
    @docx_path = docx_path
    @path = Dir.mktmpdir
  end
  
  def process(data)
    FileUtils.mkdir_p("#{@path}/legal_paper")
    `(cd #{@path}/legal_paper; unzip #{docx_path})`
    xml = File.read("#{@path}/legal_paper/word/document.xml")
    prepend = <<-XML
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
XML
    append = <<-XML
  </xsl:template>
</xsl:stylesheet>  
XML
    xslt = prepend + xml.split(/\n/)[1..-1].join("\n") + append
    tpl = xslt.gsub(/(ErlyDoc[^ \<]+)/) do |path|
      puts path.inspect
      "<xsl:value-of select=\"#{path}\"/>"
    end
    File.open("#{@path}/legal_paper.xslt", "w+") do |f|
      f << tpl
    end
    File.open("#{@path}/legal_paper.xml", "w+") do |f|
      f << data.to_xml(:root => "ErlyDoc")
    end
    `(cd #{@path}/legal_paper; xsltproc #{@path}/legal_paper.xslt #{@path}/legal_paper.xml > word/document.xml; zip -r #{@path}/legal_paper.docx *)`
    "#{@path}/legal_paper.docx"
  end
  
  def destroy
    FileUtils.rm_rf(@path)
  end
end