dwelling-radio/pkg/logging/logger.go

package logging

import (
	"fmt"
	"io"
	"os"
	"strings"
	"sync"
	"time"

	"github.com/pkg/errors"
)

type Logger struct {
	file     io.WriteCloser
	toStdout bool
	mut      sync.Mutex
}

// NewLogger creates a Logger instance with given filename and
// toStdout tells wether to write to Stdout as well or not.
func NewLogger(path string, toStdout bool) (*Logger, error) {
	f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0660)
	if err != nil {
		return nil, errors.Wrap(err, "failed to open log file")
	}

	return &Logger{file: f, toStdout: toStdout}, nil
}

func (l *Logger) Println(v ...interface{}) {
	l.mut.Lock()
	defer l.mut.Unlock()

	nowStr := time.Now().UTC().Format(time.RFC3339)

	fmt.Fprintln(l.file, nowStr, v)

	if l.toStdout {
		fmt.Println(v...)
	}
}

func (l *Logger) Printf(format string, v ...interface{}) {
	l.mut.Lock()
	defer l.mut.Unlock()

	// Ensure a new line will be written
	if !strings.HasSuffix(format, "\n") {
		format += "\n"
	}

	nowStr := time.Now().UTC().Format(time.RFC3339)

	fmt.Fprintf(l.file, nowStr+" "+format, v...)

	if l.toStdout {
		fmt.Printf(format, v...)
	}
}

func (l *Logger) Fatalln(v ...interface{}) {
	l.mut.Lock()

	nowStr := time.Now().UTC().Format(time.RFC3339)

	fmt.Fprintln(l.file, nowStr, v)

	if l.toStdout {
		fmt.Println(v...)
	}

	l.file.Close()
	os.Exit(1)
}

func (l *Logger) Fatalf(format string, v ...interface{}) {
	l.mut.Lock()

	// Ensure a new line will be written
	if !strings.HasSuffix(format, "\n") {
		format += "\n"
	}

	nowStr := time.Now().UTC().Format(time.RFC3339)

	fmt.Fprintf(l.file, nowStr+" "+format, v...)

	if l.toStdout {
		fmt.Printf(format, v...)
	}

	l.file.Close()
	os.Exit(1)
}

func (l *Logger) Close() error {
	return l.file.Close()
}