// Copyright (c) 2014, B3log
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Package log includes logging related manipulations.
//
// 	logger := log.NewLogger(os.Stdout, log.Debug)
//
// 	logger.Debug("debug message")
// 	logger.Info("info message")
// 	logger.Warn("warning message")
// 	logger.Error("error message")
//
//	logger.Errorf("formatted %s message", "error")
package log

import (
	"fmt"
	"io"
	stdlog "log"
)

// Logging level.
const (
	Debug = iota
	Info
	Warn
	Error
)

// Logger is a simple logger with level.
// The underlying logger is the Go standard logging "log".
type Logger struct {
	level  int
	logger *stdlog.Logger
}

// NewLogger creates a logger.
func NewLogger(out io.Writer, level int) *Logger {
	ret := &Logger{level: level, logger: stdlog.New(out, "", stdlog.Ldate|stdlog.Ltime|stdlog.Lshortfile)}

	return ret
}

// Debug prints debug level message.
func (l *Logger) Debug(v ...interface{}) {
	if Debug < l.level {
		return
	}

	l.logger.SetPrefix("D ")
	l.logger.Output(2, fmt.Sprint(v...))
}

// Debugf prints debug level message with format.
func (l *Logger) Debugf(format string, v ...interface{}) {
	if Debug < l.level {
		return
	}

	l.logger.SetPrefix("D ")
	l.logger.Output(2, fmt.Sprintf(format, v...))
}

// Info prints info level message.
func (l *Logger) Info(v ...interface{}) {
	if Info < l.level {
		return
	}

	l.logger.SetPrefix("I ")
	l.logger.Output(2, fmt.Sprint(v...))
}

// Infof prints info level message with format.
func (l *Logger) Infof(format string, v ...interface{}) {
	if Info < l.level {
		return
	}

	l.logger.SetPrefix("I ")
	l.logger.Output(2, fmt.Sprintf(format, v...))
}

// Warn prints warning level message.
func (l *Logger) Warn(v ...interface{}) {
	if Warn < l.level {
		return
	}

	l.logger.SetPrefix("W ")
	l.logger.Output(2, fmt.Sprint(v...))
}

// Warn prints warning level message with format.
func (l *Logger) Warnf(format string, v ...interface{}) {
	if Warn < l.level {
		return
	}

	l.logger.SetPrefix("W ")
	l.logger.Output(2, fmt.Sprintf(format, v...))
}

// Error prints error level message.
func (l *Logger) Error(v ...interface{}) {
	if Error < l.level {
		return
	}

	l.logger.SetPrefix("E ")
	l.logger.Output(2, fmt.Sprint(v...))
}

// Errorf prints error level message with format.
func (l *Logger) Errorf(format string, v ...interface{}) {
	if Error < l.level {
		return
	}

	l.logger.SetPrefix("E ")
	l.logger.Output(2, fmt.Sprintf(format, v...))
}