Template parsing

var imgAttachments := regexp.MustCompile("\\{\\{([\\s-]*img )")

func replaceImgTagsInHTML(imgs []*data.Attachment, name string) (html_template.URL, error) {
    for i := range imgs {
        if imgs[i].Name == name {
            return html_template.URL(imgs[i].Path), nil
        }
    }
    return "", fmt.Sprintf("Image attachment %v is not found", name)
}

func ParseTemplate(template string, attachments []*data.Attachment, recipient *data.Recipient, sender *data.Sender) (string, error) {
    tplVars := map[string]interface{}{
        "Recipient":     recipient,
        "Sender":        sender,
        "ImgAttachment": attachments,
    }
    content := imgAttachments.ReplaceAllString(template, "{{$1.ImgAttachment ")
    parser, err := html_template.New("Email").Funcs(html_template.FuncMap{
        "img": replaceImgTagsInHTML,
    }).Parse(content)
    if err == nil {
        wr := bytes.NewBufferString("")
        err = parser.Execute(wr, tplVars)
    }
    if err != nil{
        return "", err
    }
    return wr.String(), nil
}