logger.go

package logtamer

import (
	"io/ioutil"
	"log"
	"os"

	"github.com/gotamer/mail/send"
)

// Configuration
type LogCfg struct {
	appName    string
	File       string
	SendMailTo string // Application Admin Email
	Smtp       struct {
		Hostname string // smtp.example.com
		Hostport int    // 587
		Username string // usally email address username@example.com
		Password string
	}
}

type bool_type bool

const (
	FAKEHOSTNAME = "example.com"
	APPNAME      = "LogTamer"

	EXIT_YES bool_type = true
	EXIT_NO  bool_type = false
)

var (
	o = new(LogCfg)

	mail *send.SmtpTamer
	file *os.File

	Debug = *log.Default()
	Info  = *log.Default()
	Warn  = *log.Default()
	Error = *log.Default()
)

func init() {
	// Config file defaults
	o.File = "LogTamer.log"
	o.appName = APPNAME
	o.SendMailTo = "admin@example.com"
	o.Smtp.Hostname = FAKEHOSTNAME
	o.Smtp.Hostport = 587
	o.Smtp.Username = "user@example.com"
	o.Smtp.Password = "Long-Complicated-Secret-Pass-Word"
	Level(1)
}

func FileClose() {
	if file == nil {
		return
	}
	Info.Println("Closing log file")
	if err := file.Close(); err != nil {
		log.Fatal("Close Log File err: ", err)
	}
}

func Config() *LogCfg {
	return o
}

// Set defaults
// filename is filename including path
func Default(appname, filename string) {
	if appname != "" {
		o.appName = appname
	}
	if filename != "" {
		o.File = filename
	}
}

func Err(err error, exit bool_type, msg string) {
	if err != nil {
		if msg != "" {
			Error.Printf("%s: %w", msg, err)
		} else {
			Error.Println(err)
		}
		if exit {
			os.Exit(1)
		}
	}
}

// Switch between log levels
// Level 0 No Logging at all
// Level 1 output all to screen, is also default
// Level 2 info, warn & error to screen, debug to file
// Level 3 warn & error to screen, debug and info to file
// Level 4 warn & error to file
// Level 5 error to file
// Level 6 warn & error to mail
// Level 7 error to mail
func Level(level uint8) {

	Debug = *log.Default()
	Info = *log.Default()
	Warn = *log.Default()
	Error = *log.Default()

	Debug.SetPrefix("DBG ")
	Info.SetPrefix("INF ")
	Warn.SetPrefix("WRN ")
	Error.SetPrefix("ERR ")

	Info.SetFlags(log.Ltime | log.Lshortfile)
	Debug.SetFlags(log.Ltime | log.Lshortfile)
	Warn.SetFlags(log.Ltime | log.Lshortfile)
	Error.SetFlags(log.Ltime | log.Lshortfile)

	switch level {
	case 0:
		// Level 0 No Logging at all
		Debug.SetOutput(ioutil.Discard)
		Info.SetOutput(ioutil.Discard)
		Warn.SetOutput(ioutil.Discard)
		Error.SetOutput(ioutil.Discard)
	case 1:
		// Level 1 output all to screen, is also default
	case 2:
		// Level 2 info, warn & error to screen, debug to file
		// Log all but debug to screen aka debug mode. Debug goes to file
		openFile()
		Debug.SetOutput(file)
	case 3:
		// Level 3 warn & error to screen, debug and info to file
		openFile()
		Info.SetOutput(file)
		Debug.SetOutput(file)
	case 4:
		// Level 4 warn & error to file
		openFile()
		Warn.SetOutput(file)
		Error.SetOutput(file)
	case 5:
		// Level 5 error to file
		openFile()
		Error.SetOutput(file)
	case 6:
		// Level 6 warn & error to mail
		if o.Smtp.Hostname == "" || o.Smtp.Hostname == FAKEHOSTNAME {
			log.Fatal("ERR smtp config not set")
		}
		// email errors to admin
		mail = send.NewSMTP(o.Smtp.Hostname, o.Smtp.Username, o.Smtp.Password)
		mail.Envelop.SetFrom(o.appName, o.Smtp.Username)
		mail.Envelop.SetTo("", o.SendMailTo)
		mail.Envelop.Subject = "ERROR " + o.appName

		Debug.SetOutput(ioutil.Discard)
		Info.SetOutput(ioutil.Discard)
		Warn.SetOutput(mail)
		Error.SetOutput(mail)
	case 7:
		// Level 7 error to mail
		if o.Smtp.Hostname == "" || o.Smtp.Hostname == FAKEHOSTNAME {
			log.Fatal("ERR smtp config not set")
		}
		// email errors to admin
		mail = send.NewSMTP(o.Smtp.Hostname, o.Smtp.Username, o.Smtp.Password)
		mail.Envelop.SetFrom(o.appName, o.Smtp.Username)
		mail.Envelop.SetTo("", o.SendMailTo)
		mail.Envelop.Subject = "ERROR " + o.appName

		Debug.SetOutput(ioutil.Discard)
		Info.SetOutput(ioutil.Discard)
		Warn.SetOutput(ioutil.Discard)
		Error.SetOutput(mail)

	default:
		// Same as Level 1, output all to screen
	}
}

func openFile() {
	var err error
	file, err = os.OpenFile(o.File, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666)
	if err != nil {
		log.Fatal(err)
	}
}