package mailer

import (
	"context"
	"fmt"
	"net/smtp"
	"strings"

	"haixun-backend/internal/config"
)

type Mailer interface {
	Send(ctx context.Context, to, subject, text string) error
}

type SMTPMailer struct {
	host     string
	port     int
	username string
	password string
	from     string
}

func NewSMTPMailer(cfg config.SMTPConf) *SMTPMailer {
	if strings.TrimSpace(cfg.Host) == "" || strings.TrimSpace(cfg.From) == "" {
		return nil
	}
	return &SMTPMailer{host: cfg.Host, port: cfg.Port, username: cfg.Username, password: cfg.Password, from: cfg.From}
}

func (m *SMTPMailer) Send(ctx context.Context, to, subject, text string) error {
	if m == nil {
		return nil
	}
	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}
	addr := fmt.Sprintf("%s:%d", m.host, m.port)
	headers := []string{
		"From: " + m.from,
		"To: " + to,
		"Subject: " + subject,
		"MIME-Version: 1.0",
		"Content-Type: text/plain; charset=UTF-8",
	}
	msg := strings.Join(headers, "\r\n") + "\r\n\r\n" + text
	var auth smtp.Auth
	if m.username != "" || m.password != "" {
		auth = smtp.PlainAuth("", m.username, m.password, m.host)
	}
	return smtp.SendMail(addr, auth, m.from, []string{to}, []byte(msg))
}