Zip unpacking with Shrine while retaining the same directory structure

script.rb

require "sequel"
require "shrine"
require "shrine/storage/memory"
require "zip"
require "tempfile"
require "securerandom"

DB = Sequel.sqlite
DB.create_table :archives do
  primary_key :id
  String :attachment_data
end

Shrine.storages = {
  cache: Shrine::Storage::Memory.new,
  store: Shrine::Storage::Memory.new,
}

Shrine.plugin :sequel
Shrine.plugin :versions

class FileUploader < Shrine
  def generate_location(io, metadata: {}, record: nil, **)
    if metadata["from_zip"]
      # retain location when uploading to permanent storage
      File.join("archive/#{record.id}", metadata.fetch("filename"))
    else
      super
    end
  end
end

class Archive < Sequel::Model
  include FileUploader::Attachment.new(:attachment)
end

zip = Tempfile.new(binmode: true)

Zip::File.open(zip.path, Zip::File::CREATE) do |zip_file|
  zip_file.get_output_stream("foo.txt")     { |f| f.write "foo" }
  zip_file.get_output_stream("bar/baz.txt") { |f| f.write "barbaz" }
end

zip.flush

destination_directory = "archive/#{SecureRandom.hex}"
versions = { files: [] }

Zip::File.foreach(zip.path) do |entry|
  upload_location = File.join(destination_directory, entry.name)
  cache           = FileUploader.new(:cache)

  entry.get_input_stream do |stream|
    cached_file = cache.upload stream,
      location: upload_location,
      metadata: {
        "filename" => entry.name,
        "size"     => entry.size,
      }

    cached_file.metadata["from_zip"] = true

    versions[:files] << cached_file
  end
end

archive = Archive.new
archive.attachment_attacher.set(versions)
archive.save

archive.attachment[:files]
# => [#<FileUploader::UploadedFile:0x00007febfca079c8
#      @data=
#       {"id"=>"archive/1/foo.txt",
#        "storage"=>"store",
#        "metadata"=>
#         {"filename"=>"foo.txt",
#          "size"=>3,
#          "mime_type"=>nil,
#          "from_zip"=>true}}>,
#     #<FileUploader::UploadedFile:0x00007febfca07838
#      @data=
#       {"id"=>"archive/1/bar/baz.txt",
#        "storage"=>"store",
#        "metadata"=>
#         {"filename"=>"bar/baz.txt",
#          "size"=>6,
#          "mime_type"=>nil,
#          "from_zip"=>true}}>]