package mail

import (
	"crypto/tls"
	"fmt"
	"net"
	"net/smtp"
	"os"
	"strings"
)

type Config struct {
	Host     string
	Port     string
	Secure   bool
	User     string
	Password string
	From     string
}

func LoadConfigFromEnv() Config {
	return Config{
		Host:     strings.TrimSpace(os.Getenv("MAIL_HOST")),
		Port:     strings.TrimSpace(os.Getenv("MAIL_PORT")),
		Secure:   strings.EqualFold(os.Getenv("MAIL_SECURE"), "true"),
		User:     strings.TrimSpace(os.Getenv("MAIL_AUTH_USER")),
		Password: strings.Trim(strings.TrimSpace(os.Getenv("MAIL_AUTH_PASS")), `"`),
		From:     strings.TrimSpace(os.Getenv("MAIL_FROM")),
	}
}

func (c Config) Enabled() bool {
	return c.Host != "" && c.Port != "" && c.User != "" && c.Password != ""
}

func (c Config) fromAddr() string {
	if c.From != "" {
		return c.From
	}
	return c.User
}

func (c Config) Send(to, subject, body string) error {
	if !c.Enabled() {
		return fmt.Errorf("mail chưa cấu hình (MAIL_HOST, MAIL_AUTH_USER, MAIL_AUTH_PASS)")
	}
	msg := strings.Join([]string{
		"From: Simple Care <" + c.fromAddr() + ">",
		"To: " + to,
		"Subject: " + subject,
		"MIME-Version: 1.0",
		"Content-Type: text/html; charset=UTF-8",
		"",
		body,
	}, "\r\n")

	addr := net.JoinHostPort(c.Host, c.Port)
	auth := smtp.PlainAuth("", c.User, c.Password, c.Host)

	if c.Secure {
		tlsConfig := &tls.Config{ServerName: c.Host}
		conn, err := tls.Dial("tcp", addr, tlsConfig)
		if err != nil {
			return err
		}
		client, err := smtp.NewClient(conn, c.Host)
		if err != nil {
			return err
		}
		defer client.Close()
		if err := client.Auth(auth); err != nil {
			return err
		}
		if err := client.Mail(c.fromAddr()); err != nil {
			return err
		}
		if err := client.Rcpt(to); err != nil {
			return err
		}
		w, err := client.Data()
		if err != nil {
			return err
		}
		if _, err := w.Write([]byte(msg)); err != nil {
			return err
		}
		return w.Close()
	}

	return smtp.SendMail(addr, auth, c.fromAddr(), []string{to}, []byte(msg))
}