EagleCast

internal/notifs/notifs.go

@@ -0,0 +1,113 @@
+// package notifs is a special singleton, stateful globally accessible package
+// that handles sending out arbitrary notifications to the admin and users.
+// It's initialized once in the main package and is accessed globally across
+// other packages.
+package notifs
+
+import (
+	"bytes"
+	"html/template"
+	"log"
+	"net/textproto"
+	"regexp"
+	"strings"
+
+	"source.offmarket.win/aleagle/eaglecast/internal/messenger/email"
+	"source.offmarket.win/aleagle/eaglecast/models"
+)
+
+const (
+	TplImport          = "import-status"
+	TplCampaignStatus  = "campaign-status"
+	TplSubscriberOptin = "subscriber-optin"
+	TplSubscriberData  = "subscriber-data"
+	TplForgotPassword  = "forgot-password"
+)
+
+type FuncPush func(msg models.Message) error
+type FuncNotif func(toEmails []string, subject, tplName string, data any, headers textproto.MIMEHeader) error
+type FuncNotifSystem func(subject, tplName string, data any, headers textproto.MIMEHeader) error
+
+type Opt struct {
+	FromEmail    string
+	SystemEmails []string
+	ContentType  string
+}
+
+type Notifs struct {
+	em *email.Emailer
+	lo *log.Logger
+
+	opt Opt
+}
+
+var (
+	reTitle = regexp.MustCompile(`(?s)<title\s*data-i18n\s*>(.+?)</title>`)
+
+	Tpls *template.Template
+	no   *Notifs
+)
+
+// Initialize returns a new Notifs instance.
+func Initialize(opt Opt, tpls *template.Template, em *email.Emailer, lo *log.Logger) {
+	if no != nil {
+		lo.Fatal("notifs already initialized")
+	}
+
+	Tpls = tpls
+	no = &Notifs{
+		opt: opt,
+		em:  em,
+		lo:  lo,
+	}
+}
+
+// NotifySystem sends out an e-mail notification to the admin emails.
+func NotifySystem(subject, tplName string, data any, hdr textproto.MIMEHeader) error {
+	return Notify(no.opt.SystemEmails, subject, tplName, data, hdr)
+}
+
+// Notify sends out an e-mail notification.
+func Notify(toEmails []string, subject, tplName string, data any, hdr textproto.MIMEHeader) error {
+	if len(toEmails) == 0 {
+		return nil
+	}
+
+	var buf bytes.Buffer
+	if err := Tpls.ExecuteTemplate(&buf, tplName, data); err != nil {
+		no.lo.Printf("error compiling notification template '%s': %v", tplName, err)
+		return err
+	}
+	body := buf.Bytes()
+
+	subject, body = GetTplSubject(subject, body)
+
+	m := models.Message{
+		Messenger:   "email",
+		ContentType: no.opt.ContentType,
+		From:        no.opt.FromEmail,
+		To:          toEmails,
+		Subject:     subject,
+		Body:        body,
+		Headers:     hdr,
+	}
+
+	// Send the message.
+	if err := no.em.Push(m); err != nil {
+		no.lo.Printf("error sending admin notification (%s): %v", subject, err)
+		return err
+	}
+
+	return nil
+}
+
+// GetTplSubject extracts any custom i18n subject rendered in the given rendered
+// template body. If it's not found, the incoming subject and body are returned.
+func GetTplSubject(subject string, body []byte) (string, []byte) {
+	m := reTitle.FindSubmatch(body)
+	if len(m) != 2 {
+		return subject, body
+	}
+
+	return strings.TrimSpace(string(m[1])), reTitle.ReplaceAll(body, []byte(""))
+}