require 'socket'

#
# minimal smtp server for DataPipeline::Email tests: EHLO, AUTH LOGIN, MAIL, RCPT, DATA, QUIT
#   server = TestSmtpServer.new
#   server.mails -> [{ from:, to: [...], data:, auth: [user, password] }]
#
class TestSmtpServer
  attr_reader :mails

  def initialize
    @mails = []
    @server = TCPServer.new('127.0.0.1', 0)
    @thread = Thread.new { loop { serve(@server.accept) } }
  end

  def port = @server.addr[1]

  def stop
    @thread.kill
    @server.close
  end

  private

  def serve client
    mail = { to: [] }
    client.write "220 test ESMTP\r\n"
    while (line = client.gets)
      case line
      when /\AEHLO/i then client.write "250-test\r\n250 AUTH LOGIN PLAIN\r\n"
      when /\AAUTH LOGIN/i
        client.write "334 VXNlcm5hbWU6\r\n"
        user = client.gets.unpack1('m')
        client.write "334 UGFzc3dvcmQ6\r\n"
        mail[:auth] = [user, client.gets.unpack1('m')]
        client.write "235 ok\r\n"
      when /\AMAIL FROM:<(.*)>/i then mail[:from] = $1; client.write "250 ok\r\n"
      when /\ARCPT TO:<(.*)>/i then mail[:to] << $1; client.write "250 ok\r\n"
      when /\ADATA/i
        client.write "354 go\r\n"
        data = +''
        while (part = client.gets) && part != ".\r\n"
          data << part
        end
        mail[:data] = data
        @mails << mail
        mail = { to: [] }
        client.write "250 queued\r\n"
      when /\AQUIT/i then client.write "221 bye\r\n"; break
      else client.write "250 ok\r\n"
      end
    end
  rescue StandardError => e
    warn "TestSmtpServer: #{e.class}: #{e.message}"
  ensure
    client.close
  end
end