go_goutils/logging/funcs_file.go

package logging

import (
	`errors`
	"fmt"
	"io"
	`io/fs`
	"log"
	"os"
	`strings`
)

// Setup sets up/configures a FileLogger and prepares it for use.
func (l *FileLogger) Setup() (err error) {

	var multi io.Writer

	// This uses a shared handle across the import. We don't want that.
	// l.Logger = log.Default()
	if l.Prefix != "" {
		l.Prefix = strings.TrimRight(l.Prefix, " ") + " "
		// l.Logger.SetPrefix(l.Prefix)
	}
	if l.writer, err = os.OpenFile(l.Path, appendFlags, logPerm); err != nil {
		return
	}

	// https://stackoverflow.com/a/36719588/733214
	switch {
	case l.EnableStdErr && l.EnableStdOut:
		multi = io.MultiWriter(os.Stdout, os.Stderr, l.writer)
	case l.EnableStdErr:
		multi = io.MultiWriter(os.Stderr, l.writer)
	case l.EnableStdOut:
		multi = io.MultiWriter(os.Stdout, l.writer)
	default:
		multi = l.writer
	}

	l.Logger = log.New(multi, l.Prefix, l.LogFlags)
	// l.Logger.SetOutput(multi)

	return
}

// Shutdown cleanly shuts down a FileLogger.
func (l *FileLogger) Shutdown() (err error) {

	if err = l.writer.Close(); err != nil {
		if !errors.Is(err, fs.ErrClosed) {
			return
		}
	}

	return
}

/*
	GetPrefix returns the prefix used by this FileLogger.
	err will always be nil; it's there for interface-compat.
*/
func (l *FileLogger) GetPrefix() (prefix string, err error) {

	prefix = l.Prefix

	return
}

/*
	DoDebug sets the debug state of this FileLogger.
	Note that this merely acts as a *safety filter* for debug messages to avoid sensitive information being written to the log.
	err will always be nil; it's there for interface-compat.
*/
func (l *FileLogger) DoDebug(d bool) (err error) {

	l.EnableDebug = d

	return
}

/*
	SetPrefix sets the prefix for this FileLogger.
	err will always be nil; it's there for interface-compat.
*/
func (l *FileLogger) SetPrefix(prefix string) (err error) {

	l.Prefix = prefix
	if prefix != "" {
		l.Prefix = strings.TrimRight(l.Prefix, " ") + " "
	}
	l.Logger.SetPrefix(l.Prefix)

	return
}

// Alert writes an ALERT-level message to this FileLogger.
func (l *FileLogger) Alert(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "ALERT")

	return
}

// Crit writes an CRITICAL-level message to this FileLogger.
func (l *FileLogger) Crit(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "CRITICAL")

	return
}

// Debug writes a DEBUG-level message to this FileLogger.
func (l *FileLogger) Debug(s string, v ...interface{}) (err error) {

	if !l.EnableDebug {
		return
	}

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "DEBUG")

	return
}

// Emerg writes an EMERGENCY-level message to this FileLogger.
func (l *FileLogger) Emerg(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "EMERGENCY")

	return
}

// Err writes an ERROR-level message to this FileLogger.
func (l *FileLogger) Err(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "ERROR")

	return
}

// Info writes an INFO-level message to this FileLogger.
func (l *FileLogger) Info(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "INFO")

	return
}

// Notice writes a NOTICE-level message to this FileLogger.
func (l *FileLogger) Notice(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "NOTICE")

	return
}

// Warning writes a WARNING/WARN-level message to this FileLogger.
func (l *FileLogger) Warning(s string, v ...interface{}) (err error) {

	var msg string

	if v != nil {
		msg = fmt.Sprintf(s, v...)
	} else {
		msg = s
	}

	l.renderWrite(msg, "WARNING")

	return
}

// renderWrite prepares/formats a log message to be written to this FileLogger.
func (l *FileLogger) renderWrite(msg, prio string) {

	s := fmt.Sprintf("[%v] %v", prio, msg)

	l.Logger.Println(s)

	return
}