package maulog

import (
	"bufio"
	"fmt"
	"os"
	"time"
)

// Level is the severity level of a log entry.
type Level struct {
	Name            string
	Severity, Color int
}

// LogWriter writes to the log with an optional prefix
type LogWriter struct {
	Level  Level
	Prefix string
}

func (lw LogWriter) Write(p []byte) (n int, err error) {
	log(lw.Level, fmt.Sprint(lw.Prefix, string(p)))
	return len(p), nil
}

// GetColor gets the ANSI escape color code for the log level.
func (lvl Level) GetColor() []byte {
	if lvl.Color < 0 {
		return []byte("")
	}
	return []byte(fmt.Sprintf("\x1b[%dm", lvl.Color))
}

// GetReset gets the ANSI escape reset code.
func (lvl Level) GetReset() []byte {
	if lvl.Color < 0 {
		return []byte("")
	}
	return []byte("\x1b[0m")
}

var (
	// Debug is the level for debug messages.
	Debug = Level{Name: "DEBUG", Color: 36, Severity: 0}
	// Info is the level for basic log messages.
	Info = Level{Name: "INFO", Color: -1, Severity: 10}
	// Warn is the level saying that something went wrong, but the program will continue operating mostly normally.
	Warn = Level{Name: "WARN", Color: 33, Severity: 50}
	// Error is the level saying that something went wrong and the program may not operate as expected, but will still continue.
	Error = Level{Name: "ERROR", Color: 31, Severity: 100}
	// Fatal is the level saying that something went wrong and the program will not operate normally.
	Fatal = Level{Name: "FATAL", Color: 35, Severity: 9001}
)

// PrintLevel tells the first severity level at which messages should be printed to stdout
var PrintLevel = 10

// PrintDebug means PrintLevel = 0, kept for backwards compatibility
var PrintDebug = false

// FileTimeformat is the time format used in log file names.
var FileTimeformat = "2006-01-02"

// FileformatArgs is an undocumented integer.
var FileformatArgs = 3

// Fileformat is the format used for log file names.
var Fileformat = func(now string, i int) string { return fmt.Sprintf("%[1]s-%02[2]d.log", now, i) }

// Timeformat is the time format used in logging.
var Timeformat = "15:04:05 02.01.2006"

var writer *bufio.Writer
var lines int

// InitWithWriter initializes MauLogger with the given writer.
func InitWithWriter(w *bufio.Writer) {
	writer = w
}

// Init initializes MauLogger.
func Init() {
	// Find the next file name.
	now := time.Now().Format(FileTimeformat)
	i := 1
	for ; ; i++ {
		if _, err := os.Stat(Fileformat(now, i)); os.IsNotExist(err) {
			break
		}
		if i == 99 {
			i = 1
			break
		}
	}
	// Open the file
	file, err := os.OpenFile(Fileformat(now, i), os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0700)
	if err != nil {
		panic(err)
	}
	if file == nil {
		panic(os.ErrInvalid)
	}
	// Create a writer
	writer = bufio.NewWriter(file)
}

// Debugf formats and logs a debug message.
func Debugf(message string, args ...interface{}) {
	logln(Debug, fmt.Sprintf(message, args...))
}

// Printf formats and logs a string in the Info log level.
func Printf(message string, args ...interface{}) {
	Infof(message, args...)
}

// Infof formats and logs a string in the Info log level.
func Infof(message string, args ...interface{}) {
	logln(Info, fmt.Sprintf(message, args...))
}

// Warnf formats and logs a string in the Warn log level.
func Warnf(message string, args ...interface{}) {
	logln(Warn, fmt.Sprintf(message, args...))
}

// Errorf formats and logs a string in the Error log level.
func Errorf(message string, args ...interface{}) {
	logln(Error, fmt.Sprintf(message, args...))
}

// Fatalf formats and logs a string in the Fatal log level.
func Fatalf(message string, args ...interface{}) {
	logln(Fatal, fmt.Sprintf(message, args...))
}

// Logf formats and logs a message in the given log level.
func Logf(level Level, message string, args ...interface{}) {
	logln(level, fmt.Sprintf(message, args...))
}

// Debugln logs a debug message.
func Debugln(args ...interface{}) {
	log(Debug, fmt.Sprintln(args...))
}

// Println logs a string in the Info log level.
func Println(args ...interface{}) {
	Infoln(args...)
}

// Infoln logs a string in the Info log level.
func Infoln(args ...interface{}) {
	log(Info, fmt.Sprintln(args...))
}

// Warnln logs a string in the Warn log level.
func Warnln(args ...interface{}) {
	log(Warn, fmt.Sprintln(args...))
}

// Errorln logs a string in the Error log level.
func Errorln(args ...interface{}) {
	log(Error, fmt.Sprintln(args...))
}

// Fatalln logs a string in the Fatal log level.
func Fatalln(args ...interface{}) {
	log(Fatal, fmt.Sprintln(args...))
}

// Logln logs a message in the given log level.
func Logln(level Level, args ...interface{}) {
	log(level, fmt.Sprintln(args...))
}

func logln(level Level, message string) {
	log(level, fmt.Sprintln(message))
}

func log(level Level, message string) {
	// Prefix the message with the timestamp and log level.
	msg := []byte(fmt.Sprintf("[%[1]s] [%[2]s] %[3]s", time.Now().Format(Timeformat), level.Name, message))

	if writer != nil {
		// Write it to the log file.
		_, err := writer.Write(msg)
		if err != nil {
			panic(err)
		}
		lines++
		// Flush the file if needed
		if lines == 5 {
			lines = 0
			writer.Flush()
		}
	}

	// Print to stdout using correct color
	if level.Severity >= PrintLevel || PrintDebug {
		if level.Severity >= Error.Severity {
			os.Stderr.Write(level.GetColor())
			os.Stderr.Write(msg)
			os.Stderr.Write(level.GetReset())
		} else {
			os.Stdout.Write(level.GetColor())
			os.Stdout.Write(msg)
			os.Stdout.Write(level.GetReset())
		}
	}
}

// Shutdown cleans up the logger.
func Shutdown() {
	if writer != nil {
		writer.Flush()
	}
}