package logger

import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"sync"
	"time"
)

type defaultLogger struct {
	logLevel LogLevel
	mutex    *sync.Mutex
	stdout   io.Writer
	stderr   io.Writer
}

func (dl *defaultLogger) Debug(f string, v ...interface{}) {
	dl.log(LogLevelDebug, f, v...)
}

func (dl *defaultLogger) Info(f string, v ...interface{}) {
	dl.log(LogLevelInfo, f, v...)
}

func (dl *defaultLogger) Warn(f string, v ...interface{}) {
	dl.log(LogLevelWarn, f, v...)
}

func (dl *defaultLogger) Error(f string, v ...interface{}) {
	dl.log(LogLevelError, f, v...)
}

func (dl *defaultLogger) Fatal(f string, v ...interface{}) {
	dl.log(LogLevelFatal, f, v...)
	os.Exit(1)
}

func (dl *defaultLogger) log(ll LogLevel, f string, v ...interface{}) {

	if dl.logLevel > ll {
		return
	}

	layout := "2006/01/02 15:04:05"
	dw := dl.stdout
	prefix := ""
	switch ll {
	case LogLevelDebug:
		prefix = "DEBUG"
	case LogLevelInfo:
		prefix = "INFO"
	case LogLevelWarn:
		prefix = "WARN"
	case LogLevelError:
		prefix = "ERROR"
		dw = dl.stderr
	case LogLevelFatal:
		prefix = "FATAL"
		dw = dl.stderr
	}
	dl.mutex.Lock()
	fmt.Fprintf(dw, "%v %v: %v\n", time.Now().Format(layout), prefix, fmt.Sprintf(f, v...))
	dl.mutex.Unlock()
}

func NewDefaultLogger(logLevel LogLevel) Logger {
	return &defaultLogger{
		logLevel: logLevel,
		mutex:    new(sync.Mutex),
		stdout:   os.Stdout,
		stderr:   os.Stderr,
	}
}

func NewCustomLogger(loglevel LogLevel, out io.Writer, err io.Writer) Logger {
	return &defaultLogger{
		logLevel: loglevel,
		mutex:    new(sync.Mutex),
		stdout:   out,
		stderr:   err,
	}
}

func NewSilentLogger() Logger {
	return &defaultLogger{
		logLevel: LogLevelDebug,
		mutex:    new(sync.Mutex),
		stdout:   ioutil.Discard,
		stderr:   ioutil.Discard,
	}
}