require 'zip'

module Iconly
  # 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.
  #
  # Usage:
  #   directory_to_zip = "/tmp/input"
  #   output_file = "/tmp/out.zip"
  #   zf = ZipFileGenerator.new(directory_to_zip, output_file)
  #   zf.write()
  class ZipFileGenerator
    # Initialize with the directory to zip and the location of the output archive.
    def initialize(input_dir, output_file)
      @input_dir   = input_dir
      @output_file = output_file
    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) do |f|
        f.write(File.open(disk_file_path, 'rb').read)
      end
    end
  end
end