package e2e

import (
	"fmt"
	"net"
	"net/smtp"
	"time"
)

// port25Addr is where compose.override.yml publishes port 25: no TLS required,
// no AUTH offered - a stranger's mail server talking to this one.
const port25Addr = "127.0.0.1:20025"

// deliverPort25 is one transaction on port 25 the way another mail server makes
// it: HELO, MAIL, RCPT, DATA with message as it stands. The result says at
// which stage it was refused, like attemptSend's.
func deliverPort25(from, to, message string) sendResult {
	var res sendResult
	conn, err := net.DialTimeout("tcp", port25Addr, 10*time.Second)
	if err != nil {
		res.dialErr = fmt.Errorf("dial %s: %w", port25Addr, err)
		return res
	}
	c, err := smtp.NewClient(conn, selfpostHostname)
	if err != nil {
		res.dialErr = fmt.Errorf("smtp handshake: %w", err)
		_ = conn.Close()
		return res
	}
	defer c.Close()
	if err := c.Hello("mx.stranger.e2e.test"); err != nil {
		res.dialErr = err
		return res
	}
	if err := c.Mail(from); err != nil {
		res.mailErr = err
		_ = c.Quit()
		return res
	}
	if err := c.Rcpt(to); err != nil {
		res.rcptErr = err
		_ = c.Quit()
		return res
	}
	w, err := c.Data()
	if err != nil {
		res.dataErr = err
		_ = c.Quit()
		return res
	}
	if _, err := w.Write([]byte(message)); err != nil {
		res.dataErr = err
	} else if err := w.Close(); err != nil {
		res.dataErr = err
	}
	_ = c.Quit()
	return res
}

// waitForPort25Ready polls port 25 until Postfix greets on it. A bare connect
// is not enough: Docker's proxy accepts on the published port whether or not
// anything listens behind it (seen on the stand, date not recorded - see
// waitForSMTPSReady).
func waitForPort25Ready(timeout time.Duration) error {
	return waitFor("port 25 to greet", timeout, 500*time.Millisecond, func() (bool, error) {
		conn, err := net.DialTimeout("tcp", port25Addr, 2*time.Second)
		if err != nil {
			return false, err
		}
		defer conn.Close()
		_ = conn.SetReadDeadline(time.Now().Add(3 * time.Second))
		buf := make([]byte, 4)
		n, err := conn.Read(buf)
		if err != nil {
			return false, err
		}
		if string(buf[:n]) != "220 " {
			return false, fmt.Errorf("greeting starts with %q", buf[:n])
		}
		return true, nil
	})
}