package main

import (
	"errors"
	"fmt"
	"net/smtp"
	"os"
	"strings"

	"github.com/go-kit/kit/log"
	"github.com/go-kit/kit/log/level"
	"gopkg.in/ini.v1"
)

// mandatory parameters to send an email
type SMTPConfig struct {
	User     string
	Password string
	Url      string
	Port     string
}

func NewSMTPConfig(user, password, url, port string) (SMTPConfig, error) {
	var config SMTPConfig
	if user == "" {
		return config, errors.New("SMTP user can't be empty")
	}
	config.User = user

	if password == "" {
		return config, errors.New("SMTP password can't be empty")
	}
	config.Password = password

	if url == "" {
		return config, errors.New("SMTP server url can't be empty")
	}
	config.Url = url

	if port == "" {
		return config, errors.New("SMTP server port can't be empty")
	}
	config.Port = port

	return config, nil
}

func (c SMTPConfig) getFullUrl() string {
	return fmt.Sprintf("%s:%s", c.Url, c.Port)
}

type Email struct {
	Sender    string
	Receivers []string
	Subject   string
	Content   string
}

func NewEmail(sender string, receivers []string, subject, content string) Email {
	return Email{
		Sender:    sender,
		Receivers: receivers,
		Subject:   subject,
		Content:   content,
	}
}

func (e Email) Generate() []byte {
	mail := fmt.Sprintf(
		"To: %s\nFrom: %s\nContent-Type: text/html\nSubject: %s\n\n%s",
		strings.Join(e.Receivers, ","),
		e.Sender,
		e.Sender,
		e.Content,
	)
	return []byte(mail)
}

func GetConfigPath() (string, error) {
	switch len(os.Args) {
	case 1:
		return "", errors.New("mailsrv must have .ini config file as first parameter")
	case 2:
		return os.Args[1], nil
	default:
		return "", errors.New("mailsrv must only have one parameter: .ini path file")
	}
}

func LoadConfig(configPath string) (SMTPConfig, error) {
	var config SMTPConfig

	configPath, err := GetConfigPath()
	if err != nil {
		return config, fmt.Errorf("unable to get the .ini config path err=%v", err)
	}

	cfg, err := ini.Load(configPath)
	if err != nil {
		return config, fmt.Errorf("unable to load the .ini config path err=%v", err)
	}

	section := cfg.Section("server")
	config, err = NewSMTPConfig(
		section.Key("username").String(),
		section.Key("password").String(),
		section.Key("url").String(),
		section.Key("port").String(),
	)
	if err != nil {
		return config, fmt.Errorf("failed to load the SMTP configuration err=%v", err)
	}

	return config, nil
}

func main() {
	var logger log.Logger
	logger = log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
	logger = log.With(logger, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller, "service", "mailsrv")

	configPath, err := GetConfigPath()
	if err != nil {
		level.Error(logger).Log("msg", "unable to get the .ini config path", "err", err)
		os.Exit(1)
	}

	config, err := LoadConfig(configPath)
	if err != nil {
		level.Error(logger).Log("msg", "unable to load the SMTP configuration", "err", err)
		os.Exit(1)
	}

	logger.Log("action", "send email test")

	content := fmt.Sprintf("Hi!<br/><br/>This is an e-mail test, please do not reply.<br/><br/>Thegux Administrator<br/>%s", `<hr/>visit the website: <a href="https://thegux.fr">thegux.fr</a>`)
	email := NewEmail(config.User, []string{"receiver@receiver.com"}, "e-mail test", content)

	auth := smtp.PlainAuth("", config.User, config.Password, config.Url)
	logger.Log("action", "authentication succeed")

	fmt.Println(config.getFullUrl())

	if err := smtp.SendMail(config.getFullUrl(), auth, email.Sender, email.Receivers, email.Generate()); err != nil {
		level.Error(logger).Log("msg", "error while sending email", "err", err)
		os.Exit(1)
	}

	logger.Log("msg", "mail send successfully")
}