class ApplicationMailer < ActionMailer::Base
  default Rails.application.config.action_mailer.default_options
  layout 'mailer'

  private

    def send_mail
      @template ||= "#{self.class.name.underscore}/#{caller[0][/`([^']*)'/, 1]}"
      headers['Message-ID'] = message_id

      if @user.pgp_pubkey.present?
        mail(to: @user.email, subject: "...", content_type: pgp_content_type) do |format|
          format.text { render plain: pgp_content }
        end
      else
        mail(to: @user.email, subject: @subject) do |format|
          format.text { render @template }
        end
      end
    end

    def from_address
      self.class.default[:from]
    end

    def from_domain
      Mail::Address.new(from_address).domain
    end

    def message_id
      @message_id ||= "#{SecureRandom.uuid}@#{from_domain}"
    end

    def boundary
      @boundary ||= SecureRandom.hex(8)
    end

    def pgp_content_type
      "multipart/encrypted; protocol=\"application/pgp-encrypted\"; boundary=\"------------#{boundary}\""
    end

    def pgp_nested_content
      message_content = render_to_string(template: @template)
      message_content_base64 = Base64.encode64(message_content)
      nested_boundary = SecureRandom.hex(8)

      <<~NESTED_CONTENT
        Content-Type: multipart/mixed; boundary="------------#{nested_boundary}"; protected-headers="v1"
        Subject: #{@subject}
        From: <#{from_address}>
        To: #{@user.display_name || @user.cn} <#{@user.email}>
        Message-ID: <#{message_id}>

        --------------#{nested_boundary}
        Content-Type: text/plain; charset=UTF-8; format=flowed
        Content-Transfer-Encoding: base64

        #{message_content_base64}

        --------------#{nested_boundary}--
      NESTED_CONTENT
    end

    def pgp_content
      encrypted_content = UserManager::PgpEncrypt.call(user: @user, text: pgp_nested_content)
      encrypted_base64 = Base64.encode64(encrypted_content.to_s)

      <<~EMAIL_CONTENT
        This is an OpenPGP/MIME encrypted message (RFC 4880 and 3156)
        --------------#{boundary}
        Content-Type: application/pgp-encrypted
        Content-Description: PGP/MIME version identification

        Version: 1

        --------------#{boundary}
        Content-Type: application/octet-stream; name="encrypted.asc"
        Content-Description: OpenPGP encrypted message
        Content-Disposition: inline; filename="encrypted.asc"

        -----BEGIN PGP MESSAGE-----

        #{encrypted_base64}

        -----END PGP MESSAGE-----

        --------------#{boundary}--
      EMAIL_CONTENT
    end
end