go logger

package logger

import (
	"io"
	"log"
	"os"
)

const (
	LTrace = iota
	LInfo
	LWarn
	LError
)

var (
	file  *os.File
	Trace *log.Logger
	Info  *log.Logger
	Warn  *log.Logger
	Error *log.Logger
)

func newLevel(file *os.File, level, curLevel int) *log.Logger {
	var flag int = (log.Ldate | log.Lmicroseconds | log.Lshortfile)
	logNew := func(prefix string, l1, l2 int) *log.Logger {
		if l1 <= l2 {
			return log.New(io.MultiWriter(file, os.Stdout), prefix, flag)
		} else {
			return log.New(os.Stdout, prefix, flag)
		}
	}

	switch level {
	case LTrace:
		return logNew("[TRACE] ", curLevel, LTrace)
	case LInfo:
		return logNew("[INFO ] ", curLevel, LInfo)
	case LWarn:
		return logNew("[WARN ] ", curLevel, LWarn)
	case LError:
		return logNew("[ERROR] ", curLevel, LError)
	default:
		return logNew("[TRACE] ", curLevel, LTrace)
	}
}

func Init(path string, level int) error {
	var oldFile = file
	file, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
	if err != nil {
		return err
	}
	Trace = newLevel(file, LTrace, level)
	Info = newLevel(file, LInfo, level)
	Warn = newLevel(file, LWarn, level)
	Error = newLevel(file, LError, level)

	if oldFile != nil {
		oldFile.Close()
	}
	return nil
}

package schedule

import (
	"fmt"
	"ningtogo/app/logger"
	"time"

	"github.com/robfig/cron"
)

var (
	c *cron.Cron
)

func init() {
	c = cron.New()
	c.AddFunc("0 0 0 * * *", func() {
		initLogger()
	})
	c.Start()
	initLogger()
}

func initLogger() {
	logPath := fmt.Sprintf("logs/ningtogo_%s.log", time.Now().Format("20060102"))
	if err := logger.Init(logPath, logger.LTrace); err != nil {
		fmt.Println("init logger failed", err)
	} else {
		logger.Info.Println("logger init success")
	}
}

package main

import (
	"fmt"
	"os"

	"./logger"
)

func init() {
	if err := logger.Init("test.log", logger.LInfo); err != nil {
		fmt.Println("init logger failed", err)
		os.Exit(1)
	}
}

func main() {
	logger.Trace.Println("trace message")
	logger.Info.Println("info message")
	logger.Warn.Println("warn message")
	logger.Error.Println("error message")
}