package main

import (
	"log"
	"log/slog"
	"net/smtp"

	"github.com/emersion/go-sasl"
)

// The ANONYMOUS mechanism name.
const Anonymous = "ANONYMOUS"

type anonymousClient struct {
	Trace string
}

func (c *anonymousClient) Start(si *smtp.ServerInfo) (mech string, ir []byte, err error) {
	mech = Anonymous
	ir = []byte(c.Trace)
	return
}

func (c *anonymousClient) Next(challenge []byte, b bool) (response []byte, err error) {
	return nil, sasl.ErrUnexpectedServerChallenge
}

// A client implementation of the ANONYMOUS authentication mechanism, as
// described in RFC 4505.
func NewAnonymousClient(trace string) smtp.Auth {
	return &anonymousClient{trace}
}

// The PLAIN mechanism name.
const Plain = "PLAIN"

type plainClient struct {
	Identity string
	Username string
	Password string
}

func (a *plainClient) Start(si *smtp.ServerInfo) (mech string, ir []byte, err error) {
	mech = "PLAIN"
	ir = []byte(a.Identity + "\x00" + a.Username + "\x00" + a.Password)
	return
}

func (a *plainClient) Next(challenge []byte, b bool) (response []byte, err error) {
	slog.Info("Next: %v", challenge)
	return nil, nil
}

// A client implementation of the PLAIN authentication mechanism, as described
// in RFC 4616. Authorization identity may be left blank to indicate that it is
// the same as the username.
func NewPlainClient(identity, username, password string) smtp.Auth {
	return &plainClient{identity, username, password}
}

func main() {
	// hostname is used by PlainAuth to validate the TLS certificate.
	hostname := "localhost"
	auth := NewPlainClient("", "username", "password")
	// auth := NewAnonymousClient("test")
	recipients := []string{"something@something.com", "caca@caca.com"}
	msg := []byte("\r\nwithout title")
	from := "hello@localhost"
	err := smtp.SendMail(hostname+":11025", auth, from, recipients, msg)
	if err != nil {
		log.Fatal(err)
	}
}