Zip file generator in ruby, suitable for templating OOXML documents (DOCX, XLSX, …)

erb_zip_file_generator.rb

# This is a simple example which uses rubyzip to recursively generate a zip file from the contents of a specified directory. The
# directory itself is not included in the archive, rather just its contents.
#
# The generator has been extended to support ERB templates: Files with an extension ending in `.erb` will be processed by ERB
# before they are added to the archive (the filename in the archive will have `.erb` stripped).
#
# Suitable for templating OOXML documents (eg. DOCX or AXSLX): Just create the template document in the office application of your
# choice, rename the extension to ".zip" and unzip the file. Now add ERB code to individual files as needed (for DOCX you’ll most
# likely want to edit `word/document.xml`). Don't forget to also add an additonial `.erb` extension to those files! Then run
# ErbZipGenerator on the top level directory and with a suitable output filename – done!
#
# Usage:
#   directoryToZip = "/tmp/input/document"
#   outputFile = "/tmp/document.docx"
#   zf = ZipFileGenerator.new(directoryToZip, outputFile, binding)
#   zf.write()
#
# Based on https://github.com/rubyzip/rubyzip/blob/05916bf89181e1955118fd3ea059f18acac28cc8/samples/example_recursive.rb

require 'zip'

class ErbZipFileGenerator
  # Initialize with the directory to zip and the location of the output archive.
  def initialize(input_dir, output_file, erb_binding)
    @input_dir = input_dir
    @output_file = output_file
    @erb_binding = erb_binding
  end

  # Zip the input directory.
  def write
    entries = Dir.entries(@input_dir) - %w(. ..)

    ::Zip::File.open(@output_file, ::Zip::File::CREATE) do |io|
      write_entries entries, '', io
    end
  end

  private

  # A helper method to make the recursion work.
  def write_entries(entries, path, io)
    entries.each do |e|
      zip_file_path = path == '' ? e : File.join(path, e)
      disk_file_path = File.join(@input_dir, zip_file_path)
      if File.directory? disk_file_path
        recursively_deflate_directory(disk_file_path, io, zip_file_path)
      else
        put_into_archive(disk_file_path, io, zip_file_path)
      end
    end
  end

  def recursively_deflate_directory(disk_file_path, io, zip_file_path)
    io.mkdir zip_file_path
    subdir = Dir.entries(disk_file_path) - %w(. ..)
    write_entries subdir, zip_file_path, io
  end

  def put_into_archive(disk_file_path, io, zip_file_path)
    io.get_output_stream(zip_file_path.sub(/\.erb$/, '')) do |f|
      contents = if disk_file_path.end_with?('.erb')
        ERB.new(File.read(disk_file_path)).result(@erb_binding)
      else
        File.open(disk_file_path, 'rb').read
      end
      f.puts(contents)
    end
  end
end