refactor, working prototype

pkg/inline.go

@@ -0,0 +1,84 @@
+package gomailer
+
+import (
+	"log"
+	"os"
+	"path"
+	"strings"
+	"golang.org/x/net/html"
+	"github.com/vanng822/go-premailer/premailer"
+)
+
+func Inline(arg string) {
+	out := LoadTemplate(arg, true)
+
+	dir := path.Dir(arg)
+	ext := path.Ext(arg)
+	base := strings.ReplaceAll(path.Base(arg), ext, "")
+	output_file := path.Join(dir, base+"_inlined"+ext)
+	log.Printf("Template: %s -> %s", arg, output_file)
+
+	f, err := os.Create(output_file)
+	if err != nil {
+		log.Fatal("error inlining html: " + err.Error())
+	}
+	_, err = f.WriteString(out)
+
+	if err != nil {
+		log.Fatal("error inlining html: " + err.Error())
+	}
+}
+
+func LoadTemplate(template string, inline bool) (string) {
+	rawhtml, err := os.ReadFile(template)
+	if err != nil {
+			log.Fatal("error loading template: " + err.Error())
+	}
+
+	if inline {
+		prem, err := premailer.NewPremailerFromBytes(rawhtml, premailer.NewOptions())
+		if err != nil {
+			log.Fatal("error inlining html: " + err.Error())
+		}
+
+		inlinehtml, err := prem.Transform()
+		if err != nil {
+			log.Fatal("error transforming html: " + err.Error())
+		}
+		return inlinehtml
+	}
+
+	return string(rawhtml)
+}
+
+func FindSrcInHtml(doc string) []string {
+	var results []string
+	reader := strings.NewReader(doc)
+	if document, err := html.Parse(reader); err == nil {
+
+		var parser func(*html.Node)
+		parser = func(n *html.Node) {
+			if n.Type == html.ElementNode && n.Data == "img" {
+
+				var imgSrcUrl string
+
+				for _, element := range n.Attr {
+					if element.Key == "src" {
+						imgSrcUrl = element.Val
+						log.Print("found image:" + imgSrcUrl)
+						results = append(results, imgSrcUrl)
+					}
+				}
+			}
+
+			for c := n.FirstChild; c != nil; c = c.NextSibling {
+				parser(c)
+			}
+
+		}
+		parser(document)
+	} else {
+		log.Fatalln("Parse html error", err)
+	}
+	return results
+}

pkg/mail.go

@@ -0,0 +1,112 @@
+package gomailer
+
+import (
+	"crypto/tls"
+	"github.com/wneessen/go-mail"
+	ht "html/template"
+	"log"
+)
+
+type MailSettings struct {
+	Subject  string
+	From     string
+	To       string
+	Cc       string
+	Inline   bool
+	Template string
+}
+
+type MailServer struct {
+	Port       int
+	Host       string
+	Username   string
+	Password   string
+	Tls        string
+	Authtype   string
+	Skipverify bool
+}
+
+func SendMail(mailsettings MailSettings, serversettings MailServer) {
+	html := LoadTemplate(mailsettings.Template, true)
+
+	m := mail.NewMsg()
+	if err := m.From(mailsettings.From); err != nil {
+		log.Fatalf("failed to set From address: %s", err)
+	}
+	if err := m.To(mailsettings.From); err != nil {
+		log.Fatalf("failed to set To address: %s", err)
+	}
+
+	m.Subject(mailsettings.Subject)
+
+	htpl, err := ht.New("htmltpl").Parse(html)
+	if err != nil {
+		log.Fatalf("failed to parse text template: %s", err)
+	}
+
+	// embedd images
+	for _, val := range FindSrcInHtml(html) {
+		log.Println("Embedding: " + val)
+		m.EmbedFile(val)
+	}
+
+	// set template
+	m.SetBodyHTMLTemplate(htpl, nil)
+
+	// generate client
+	c, err := getClient(serversettings)
+	if err != nil {
+		log.Fatalf("failed to create mail client: %s", err)
+	}
+
+	// send mail
+	if err := c.DialAndSend(m); err != nil {
+		log.Fatalf("failed to send mail: %s", err)
+	}
+}
+
+func getClient(config MailServer) (*mail.Client, error) {
+	var authType mail.SMTPAuthType
+	switch config.Authtype {
+	case "plain":
+		authType = mail.SMTPAuthPlain
+	case "login":
+		authType = mail.SMTPAuthLogin
+	case "cram-md5":
+		authType = mail.SMTPAuthCramMD5
+	}
+
+	// tlsPolicy := mail.TLSOpportunistic
+	tlsPolicy := mail.DefaultTLSPolicy
+	switch config.Tls {
+	case "notls":
+		tlsPolicy = mail.NoTLS
+	case "mandatory":
+		tlsPolicy = mail.TLSMandatory
+	}
+
+	opts := []mail.Option{
+		mail.WithPort(config.Port),
+		mail.WithTLSPolicy(tlsPolicy),
+		mail.WithTLSConfig(&tls.Config{
+			InsecureSkipVerify: config.Skipverify,
+		}),
+	}
+
+	if config.Authtype != "nologin" {
+		opts = append(opts, mail.WithSMTPAuth(authType))
+	}
+
+	if config.Username != "" {
+		opts = append(opts, mail.WithUsername(config.Username))
+	}
+
+	if config.Password != "" {
+		opts = append(opts, mail.WithPassword(config.Password))
+	}
+
+	return mail.NewClient(
+		config.Host,
+		opts...,
+	)
+}