gmantaos/Goirate

package main

import (
    "bytes"
    "fmt"
    "html/template"
    "net/smtp"
    "strings"

    "github.com/gobuffalo/packr"
)

// SMTPConfig holds the host information and credentials for sending e-mails using SMTP.
type SMTPConfig struct {
    Host          string `toml:"host"`
    Port          uint16 `toml:"port"`
    Username      string `toml:"username"`
    Password      string `toml:"password"`
    From          string `toml:"from"`
    SubjectPrefix string `toml:"subject_prefix"`
}

// SendEmail sends the e-mail body to the given receiver over SMTP.
func (cfg *SMTPConfig) SendEmail(subject, body string, to ...string) error {

    for i := range to {
        to[i] = strings.TrimSpace(to[i])
    }

    if cfg.SubjectPrefix != "" {
        subject = fmt.Sprintf("%s %s", cfg.SubjectPrefix, subject)
    }

    fromString := cfg.From

    if fromString == "" {
        fromString = fmt.Sprintf("Goirate <%s>", cfg.Username)
    }

    mime := "MIME-version: 1.0;\nContent-Type: text/html; charset=\"UTF-8\";\n\n"

    commaSeparatedTo := strings.Join(to, ",")

    msg := fmt.Sprintf("From: %v\nTo: %s\nSubject: %s\n%s\n\n%s\n", fromString, commaSeparatedTo, subject, mime, body)

    err := smtp.SendMail(
        fmt.Sprintf("%s:%d", cfg.Host, cfg.Port),
        smtp.PlainAuth("", cfg.Username, cfg.Password, cfg.Host),
        cfg.Username,
        to,
        []byte(msg),
    )

    return err
}

// LoadSeriesTemplate generates the torrent notification e-mail by loading the template
// and populating it with the given data.
func LoadSeriesTemplate(data interface{}) (string, error) {

    box := packr.NewBox("../mail_templates")

    html, err := box.FindString("series.html")

    if err != nil {
        return "", err
    }

    templ, err := template.New("tml").Parse(html)

    if err != nil {
        return "", err
    }

    buf := new(bytes.Buffer)

    if err = templ.Execute(buf, data); err != nil {
        return "", err
    }

    return buf.String(), nil
}