require 'digest'

class MaterialFileSha256
  def self.from_blob blob, allow_download: false
    sha256 = blob.metadata['sha256']
    return sha256 if sha256.present?
    return nil unless allow_download

    begin
      blob.open do |file|
        sha256 = Digest::SHA256.file(file.path).hexdigest
        blob.metadata['sha256'] = sha256
        blob.save! if blob.changed?
        sha256
      end
    rescue ActiveStorage::FileNotFoundError, ArgumentError => error
      Rails.logger.warn(
          "MaterialFileSha256.from_blob failed for blob_id=#{blob.id}: " \
          "#{error.class}: #{error.message}",
      )
      nil
    end
  end

  def self.from_upload upload
    tempfile = upload&.tempfile
    return nil unless tempfile

    tempfile.rewind
    Digest::SHA256.file(tempfile.path).hexdigest.tap do
      tempfile.rewind
    end
  end
end