class ActiveStorage::Service::DiskService

def compose(source_keys, destination_key, **)
  File.open(make_path_for(destination_key), "w") do |destination_file|
    source_keys.each do |source_key|
      File.open(path_for(source_key), "rb") do |source_file|
        IO.copy_stream(source_file, destination_file)
      end
    end
  end
end

def delete(key)
  instrument :delete, key: key do
    File.delete path_for(key)
  rescue Errno::ENOENT
    # Ignore files already deleted
  end
end

def delete_prefixed(prefix)
  instrument :delete_prefixed, prefix: prefix do
    Dir.glob(path_for("#{prefix}*")).each do |path|
      FileUtils.rm_rf(path)
    end
  end
end

def download(key, &block)
  if block_given?
    instrument :streaming_download, key: key do
      stream key, &block
    end
  else
    instrument :download, key: key do
      File.binread path_for(key)
    rescue Errno::ENOENT
      raise ActiveStorage::FileNotFoundError
    end
  end
end

def download_chunk(key, range)
  instrument :download_chunk, key: key, range: range do
    File.open(path_for(key), "rb") do |file|
      file.seek range.begin
      file.read range.size
    end
  rescue Errno::ENOENT
    raise ActiveStorage::FileNotFoundError
  end
end

def ensure_integrity_of(key, checksum)
  unless OpenSSL::Digest::MD5.file(path_for(key)).base64digest == checksum
    delete key
    raise ActiveStorage::IntegrityError
  end
end

def exist?(key)
  instrument :exist, key: key do |payload|
    answer = File.exist? path_for(key)
    payload[:exist] = answer
    answer
  end
end

def folder_for(key)
  [ key[0..1], key[2..3] ].join("/")
end

def generate_url(key, expires_in:, filename:, content_type:, disposition:)
  content_disposition = content_disposition_with(type: disposition, filename: filename)
  verified_key_with_expiration = ActiveStorage.verifier.generate(
    {
      key: key,
      disposition: content_disposition,
      content_type: content_type,
      service_name: name
    },
    expires_in: expires_in,
    purpose: :blob_key
  )
  if url_options.blank?
    raise ArgumentError, "Cannot generate URL for #{filename} using Disk service, please set ActiveStorage::Current.url_options."
  end
  url_helpers.rails_disk_service_url(verified_key_with_expiration, filename: filename, **url_options)
end

def headers_for_direct_upload(key, content_type:, **)
  { "Content-Type" => content_type }
end

def initialize(root:, public: false, **options)
  @root = root
  @public = public
end

def make_path_for(key)
  path_for(key).tap { |path| FileUtils.mkdir_p File.dirname(path) }
end

def path_for(key) # :nodoc:
  File.join root, folder_for(key), key
end

def private_url(key, expires_in:, filename:, content_type:, disposition:, **)
  generate_url(key, expires_in: expires_in, filename: filename, content_type: content_type, disposition: disposition)
end

def public_url(key, filename:, content_type: nil, disposition: :attachment, **)
  generate_url(key, expires_in: nil, filename: filename, content_type: content_type, disposition: disposition)
end

def stream(key)
  File.open(path_for(key), "rb") do |file|
    while data = file.read(5.megabytes)
      yield data
    end
  end
rescue Errno::ENOENT
  raise ActiveStorage::FileNotFoundError
end

def upload(key, io, checksum: nil, **)
  instrument :upload, key: key, checksum: checksum do
    IO.copy_stream(io, make_path_for(key))
    ensure_integrity_of(key, checksum) if checksum
  end
end

def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:, custom_metadata: {})
  instrument :url, key: key do |payload|
    verified_token_with_expiration = ActiveStorage.verifier.generate(
      {
        key: key,
        content_type: content_type,
        content_length: content_length,
        checksum: checksum,
        service_name: name
      },
      expires_in: expires_in,
      purpose: :blob_token
    )
    url_helpers.update_rails_disk_service_url(verified_token_with_expiration, url_options).tap do |generated_url|
      payload[:url] = generated_url
    end
  end
end

def url_helpers
  @url_helpers ||= Rails.application.routes.url_helpers
end

def url_options
  ActiveStorage::Current.url_options
end