feat: add template engine to mail

This commit also introduced the capability to define multiple mail recipients using a comma separated list of addresses

config.go

@@ -12,6 +12,11 @@ type MailSendConfig struct {
 	To   string `json:"to"`
 }
 
+type MailTemplate struct {
+	Subject string `json:"subject"`
+	Body    string `json:"body"`
+}
+
 type SMTPConfig struct {
 	Host     string           `json:"host"`
 	Port     string           `json:"port"`
@@ -19,6 +24,7 @@ type SMTPConfig struct {
 	Password string           `json:"password"`
 	Insecure bool             `json:"insecure"`
 	Mails    []MailSendConfig `json:"mails"`
+	Template *MailTemplate    `json:"template"`
 }
 
 type Config struct {
@@ -73,8 +79,10 @@ func loadConfig() *Config {
 	mailInsecureFlag := flag.Bool("mail-insecure", false, "mail notification system: allow insecure communications(optional)")
 	mailFromFlag := flag.String("mail-from", "", "mail notification system: sender mail(optional)")
 	mailToFlag := flag.String("mail-to", "", "mail notification system: receiver mail(optional)")
+	mailSubjectTemplateFlag := flag.String("mail-subject-template", "", "mail notification system: mail subject template(optional)")
+	mailBodyTemplateFlag := flag.String("mail-body-template", "", "mail notification system: mail body template(optional)")
 
-	configFile := flag.String("config", "", "Path to JSON config file. If this flag is provided all the others are ignored")
+	configFile := flag.String("config", "", "Path to JSON config file. If this flag is provided all the others will override the loaded config file")
 
 	// Parse command line flags
 	flag.Parse()
@@ -145,6 +153,14 @@ func loadConfig() *Config {
 		initMailConfsIfNeeded()
 		config.SMTP.Mails[0].To = *mailToFlag
 	}
+	if *mailSubjectTemplateFlag != "" {
+		initSmtpConfigIfNeeded()
+		config.SMTP.Template.Subject = *mailSubjectTemplateFlag
+	}
+	if *mailBodyTemplateFlag != "" {
+		initSmtpConfigIfNeeded()
+		config.SMTP.Template.Body = *mailBodyTemplateFlag
+	}
 
 	return config
 }

config.json.example

@@ -13,6 +13,11 @@
         "port": "465",
         "username": "my-user@example.com",
         "password": "my-password",
+        "insecure": false,
+        "template": {
+            "subject": "{{if not .Success}}[FAILED]{{else}}[SUCCESS]{{end}} Backup report for {{.Datastore}}",
+            "body": "Backup {{if .Success}}completed{{else}}ended with errors{{end}} on host {{.Hostname}} (took {{.FromattedDuration}})\n{{if .Success}}Chunks New {{.NewChunks}}, Reused {{.ReusedChunks}}.{{else}}Error occurred while working, backup may be not completed.\nLast error is: {{.ErrorStr}}{{end}}"
+        },
         "mails": [{
             "from": "sender1@example.com",
             "to": "receiver1@example.com

mail.go

@@ -4,7 +4,10 @@ import (
 	"crypto/tls"
 	"errors"
 	"fmt"
+	"html/template"
 	"net/smtp"
+	"strings"
+	"time"
 )
 
 type unencryptedAuth struct {
@@ -76,7 +79,12 @@ func sendMail(from, to, subject, body string, c *smtp.Client) error {
 	// Setup headers
 	headers := make(map[string]string)
 	headers["From"] = from
-	headers["To"] = to
+	recipients := strings.Split(to, ",")
+	recipientsStr := make([]string, 0)
+	for i := range recipients {
+		recipientsStr = append(recipientsStr, fmt.Sprintf("<%s>", recipients[i]))
+	}
+	headers["To"] = strings.Join(recipientsStr, ",")
 	headers["Subject"] = subject
 
 	// Setup message
@@ -91,7 +99,7 @@ func sendMail(from, to, subject, body string, c *smtp.Client) error {
 		return err
 	}
 
-	if err := c.Rcpt(to); err != nil {
+	if err := c.Rcpt(strings.Join(recipientsStr, ",")); err != nil {
 		return err
 	}
 
@@ -113,3 +121,49 @@ func sendMail(from, to, subject, body string, c *smtp.Client) error {
 
 	return nil
 }
+
+type mailCtx struct {
+	NewChunks    uint64
+	ReusedChunks uint64
+	Datastore    string
+	Error        error
+	Hostname     string
+	StartTime    time.Time
+	EndTime      time.Time
+}
+
+func (m *mailCtx) Duration() time.Duration {
+	return m.EndTime.Sub(m.StartTime)
+}
+
+func (m *mailCtx) FromattedDuration() string {
+	return m.Duration().String()
+}
+
+func (m *mailCtx) ErrorStr() string {
+	if m.Error != nil {
+		return m.Error.Error()
+	}
+	return ""
+}
+
+func (m *mailCtx) Success() bool {
+	return m.Error == nil
+}
+
+func (m *mailCtx) Status() string {
+	if m.Success() {
+		return "Success"
+	}
+	return "Failed"
+}
+
+func (m *mailCtx) buildStr(txt string) (string, error) {
+	tmpl, err := template.New("mail").Parse(txt)
+	if err != nil {
+		return "", err
+	}
+	strBuff := &strings.Builder{}
+	err = tmpl.Execute(strBuff, m)
+	return strBuff.String(), err
+}

main.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"runtime"
 	"sync/atomic"
+	"time"
 
 	"github.com/cornelk/hashmap"
 	"github.com/gen2brain/beeep"
@@ -18,6 +19,11 @@ import (
 	"github.com/tawesoft/golib/v2/dialog"
 )
 
+var defaultMailSubjectTemplate = "Backup {{.Status}}"
+var defaultMailBodyTemplate = `{{if .Success}}Backup complete ({{.FromattedDuration}})
+Chunks New {{.NewChunks}}, Reused {{.ReusedChunks}}.{{else}}Error occurred while working, backup may be not completed.
+Last error is: {{.ErrorStr}}{{end}}`
+
 var didxMagic = []byte{28, 145, 78, 165, 25, 186, 179, 205}
 
 type ChunkState struct {
@@ -94,15 +100,41 @@ func main() {
 			BackupID: cfg.BackupID,
 		},
 	}
+	hostname, err := os.Hostname()
+	if err != nil {
+		fmt.Println("Failed to retrieve hostname:", err)
+		hostname = "unknown"
+	}
 
-	err := backup(client, newchunk, reusechunk, cfg.PxarOut, cfg.BackupSourceDir)
+	begin := time.Now()
+	err = backup(client, newchunk, reusechunk, cfg.PxarOut, cfg.BackupSourceDir)
+	end := time.Now()
 
-	fmt.Printf("New %d , Reused %d\n", newchunk.Load(), reusechunk.Load())
+	mailCtx := mailCtx{
+		NewChunks:    newchunk.Load(),
+		ReusedChunks: reusechunk.Load(),
+		Error:        err,
+		Hostname:     hostname,
+		Datastore:    cfg.Datastore,
+		StartTime:    begin,
+		EndTime:      end,
+	}
+
+	mailBodyTemplate := defaultMailBodyTemplate
+	if cfg.SMTP != nil && cfg.SMTP.Template != nil && cfg.SMTP.Template.Body != "" {
+		mailBodyTemplate = cfg.SMTP.Template.Body
+	}
+
+	fmt.Printf("New %d, Reused %d, backup took %s.\n", newchunk.Load(), reusechunk.Load(), end.Sub(begin))
 	var msg string
-	if err == nil {
-		msg = fmt.Sprintf("Backup complete\nChunks New %d , Reused %d\n", newchunk.Load(), reusechunk.Load())
-	} else {
-		msg = fmt.Sprintf("Error occurred while working, backup may be not completed.\nLast error is: %s\n", err.Error())
+	msg, err = mailCtx.buildStr(mailBodyTemplate)
+	if err != nil {
+		fmt.Println("Cannot use custom mail body: " + err.Error())
+		msg, err = mailCtx.buildStr(defaultMailBodyTemplate)
+		if err != nil {
+			// this should never happen
+			panic(err)
+		}
 	}
 	if runtime.GOOS == "windows" {
 		systray.Quit()
@@ -110,10 +142,20 @@ func main() {
 	}
 	if cfg.SMTP != nil {
 		var subject string
-		if err == nil {
-			subject = "Backup complete"
-		} else {
-			subject = "Backup error"
+
+		mailSubjectTemplate := defaultMailSubjectTemplate
+		if cfg.SMTP.Template != nil && cfg.SMTP.Template.Subject != "" {
+			mailSubjectTemplate = cfg.SMTP.Template.Subject
+		}
+
+		subject, err = mailCtx.buildStr(mailSubjectTemplate)
+		if err != nil {
+			fmt.Println("Cannot use custom mail subject: " + err.Error())
+			msg, err = mailCtx.buildStr(defaultMailSubjectTemplate)
+			if err != nil {
+				// this should never happen
+				panic(err)
+			}
 		}
 		client, err := setupClient(cfg.SMTP.Host, cfg.SMTP.Port, cfg.SMTP.Username, cfg.SMTP.Password, cfg.SMTP.Insecure)
 		if err != nil {