class ActiveStorage::Service::DiskService

def current_host
  ActiveStorage::Current.host
end

def delete(key)
  instrument :delete, key: key do
    begin
      File.delete path_for(key)
    rescue Errno::ENOENT
      # Ignore files already deleted
    end
  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)
  if block_given?
    instrument :streaming_download, key: key do
      File.open(path_for(key), "rb") do |file|
        while data = file.read(5.megabytes)
          yield data
        end
      end
    end
  else
    instrument :download, key: key do
      File.binread path_for(key)
    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
  end
end

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

def initialize(root:)
  @root = root
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 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(key, expires_in:, filename:, disposition:, content_type:)
  instrument :url, key: key do |payload|
    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
      },
      { expires_in: expires_in,
      purpose: :blob_key }
    )
    generated_url = url_helpers.rails_disk_service_url(verified_key_with_expiration,
      host: current_host,
      disposition: content_disposition,
      content_type: content_type,
      filename: filename
    )
    payload[:url] = generated_url
    generated_url
  end
end

def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
  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
      },
      { expires_in: expires_in,
      purpose: :blob_token }
    )
    generated_url = url_helpers.update_rails_disk_service_url(verified_token_with_expiration, host: current_host)
    payload[:url] = generated_url
    generated_url
  end
end

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