package emailing

import (
	"bytes"
	"fmt"
	"html/template"

	"github.com/spf13/viper"
	"github.com/wneessen/go-mail"
)

type Mailer struct {
	TemplatesDir    string
	TemplatesConfig *viper.Viper
	SMTPConfig
}

type SMTPConfig struct {
	Host     string
	Port     int
	Username string
	Password string
}

type Option func(*mail.Msg, []mail.Option) ([]mail.Option, error)

func NewMailer(templates_dir string, tplcfg *viper.Viper, smtpconfig *viper.Viper) (*Mailer, error) {
	return &Mailer{
		TemplatesDir:    templates_dir,
		TemplatesConfig: tplcfg,
		SMTPConfig: SMTPConfig{
			Host:     smtpconfig.GetString("host"),
			Port:     smtpconfig.GetInt("port"),
			Username: smtpconfig.GetString("username"),
			Password: smtpconfig.GetString("password"),
		},
	}, nil
}

func (m *Mailer) Send(emailcfg string, to string, data any, opts ...Option) error {
	cfg := m.TemplatesConfig.Sub(emailcfg)

	files := cfg.GetStringSlice("files")
	prefixed_files := []string{}
	for _, f := range files {
		prefixed_files = append(prefixed_files, m.TemplatesDir+f)
	}
	t := template.New("email").Funcs(
		template.FuncMap{
			"unescapeHTML":  UnescapeHTML,
		},
	)
	t = template.Must(t.ParseFiles(prefixed_files...))
	buf := new(bytes.Buffer)
	if err := t.ExecuteTemplate(buf, "main", data); err != nil {
		return fmt.Errorf("failed execute mail template : %w", err)
	}
	body := buf.String()

	message := mail.NewMsg()
	if err := message.From(m.SMTPConfig.Username); err != nil {
		return fmt.Errorf("failed to set From header : %w", err)
	}
	if err := message.To(to); err != nil {
		return fmt.Errorf("failed to set To header : %w", err)
	}
	message.Subject(cfg.GetString("subject"))
	message.SetBodyString(mail.TypeTextHTML, body)

	dialOptions := []mail.Option{
		//mail.WithSMTPAuth(mail.SMTPAuthAutoDiscover), 
		mail.WithSMTPAuth(mail.SMTPAuthNoAuth), 
		mail.WithUsername(m.SMTPConfig.Username), 
		mail.WithPassword(m.SMTPConfig.Password),
	}

	fmt.Println(dialOptions)

	for _, opt := range opts {
		no, err := opt(message, dialOptions) 
		if err != nil {
			return fmt.Errorf("failed to set option : %w", err)
		}
		dialOptions = no
  }

	fmt.Println(dialOptions)

	client, err := mail.NewClient(m.SMTPConfig.Host, dialOptions...)
	if err != nil {
		return fmt.Errorf("failed to create mail client : %w", err)
	}

	if err := client.DialAndSend(message); err != nil {
		return fmt.Errorf("failed to send message : %w", err)
	}

	return nil

}

func WithReplyTo(email string) Option {
	return func(m *mail.Msg, opts []mail.Option) ([]mail.Option, error) {
		return opts, m.ReplyTo(email)
	}
}

func WithTLSOpportunistic() Option {
	return func(m *mail.Msg, opts []mail.Option) ([]mail.Option, error) {
		opts = append(opts, mail.WithTLSPolicy(mail.TLSOpportunistic))
		return opts, nil
	}
}

func UnescapeHTML(s string) template.HTML {
	return template.HTML(s)
}