package logr

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

var defaultLogger = New(LevelInfo, false, os.Stdout)

type Logger struct {
	// threshold is the minimum level output by this logger.
	//
	// For example, if the threshold is set to LevelWarn, then only logs of LevelWarn and LevelError will be output
	// while logs of LevelDebug and LevelInfo will be ignored.
	//
	// Defaults to LevelInfo.
	threshold Level

	// shouldPrefixMessageWithLevel is whether to include the log level prefix in each log.
	//
	// For example, if this is set to true, then a debug log would output "<date> DEBUG <message>"
	//
	// Defaults to false.
	shouldPrefixMessageWithLevel bool

	stdLogger *log.Logger
}

// New creates a new logger with the given threshold and output.
func New(threshold Level, shouldPrefixMessageWithLevel bool, output io.Writer) *Logger {
	if !threshold.IsValid() {
		threshold = LevelInfo // Default to LevelInfo if the threshold is invalid
	}
	return &Logger{
		threshold:                    threshold,
		shouldPrefixMessageWithLevel: shouldPrefixMessageWithLevel,
		stdLogger:                    log.New(output, "", log.LstdFlags),
	}
}

func (logger *Logger) SetOutput(output io.Writer) {
	// Because we're using the standard log package under the hood, we can just directly pass this
	// to the logger and call it a day. It already takes care of locking and discarding the previous writer.
	logger.stdLogger.SetOutput(output)
}

func (logger *Logger) SetThreshold(threshold Level) {
	if !threshold.IsValid() {
		threshold = LevelInfo // Default to LevelInfo if the threshold is invalid
	} else {
		logger.threshold = threshold
	}
}

func (logger *Logger) GetThreshold() Level {
	return logger.threshold
}

func (logger *Logger) Log(level Level, message string) {
	logger.Logf(level, message)
}

func (logger *Logger) Logf(level Level, format string, args ...any) {
	if level.Value() < logger.threshold.Value() {
		// The log level is below the threshold, so ignore the log
		return
	}
	if logger.shouldPrefixMessageWithLevel {
		format = "- " + string(level) + " - " + format
	}
	logger.stdLogger.Printf(format, args...)
	if level == LevelFatal {
		os.Exit(1)
	}
}

func (logger *Logger) Debug(message string) {
	logger.Log(LevelDebug, message)
}

func (logger *Logger) Debugf(format string, args ...any) {
	logger.Logf(LevelDebug, format, args...)
}

func (logger *Logger) Info(message string) {
	logger.Log(LevelInfo, message)
}

func (logger *Logger) Infof(format string, args ...any) {
	logger.Logf(LevelInfo, format, args...)
}

func (logger *Logger) Warn(message string) {
	logger.Log(LevelWarn, message)
}

func (logger *Logger) Warnf(format string, args ...any) {
	logger.Logf(LevelWarn, format, args...)
}

func (logger *Logger) Error(message string) {
	logger.Log(LevelError, message)
}

func (logger *Logger) Errorf(format string, args ...any) {
	logger.Logf(LevelError, format, args...)
}

func (logger *Logger) Fatal(message string) {
	logger.Log(LevelFatal, message)
}

func (logger *Logger) Fatalf(format string, args ...any) {
	logger.Logf(LevelFatal, format, args...)
}

// SetOutput sets the output of the default logger
func SetOutput(output io.Writer) {
	defaultLogger.SetOutput(output)
}

// SetThreshold sets the minimum level output by the default logger
func SetThreshold(threshold Level) {
	defaultLogger.SetThreshold(threshold)
}

func GetThreshold() Level {
	return defaultLogger.GetThreshold()
}

func Log(level Level, message string) {
	defaultLogger.Log(level, message)
}

func Logf(level Level, message string, args ...any) {
	defaultLogger.Logf(level, message, args)
}

func Debug(message string) {
	defaultLogger.Debug(message)
}

func Debugf(format string, args ...any) {
	defaultLogger.Debugf(format, args...)
}

func Info(message string) {
	defaultLogger.Info(message)
}

func Infof(format string, args ...any) {
	defaultLogger.Infof(format, args...)
}

func Warn(message string) {
	defaultLogger.Warn(message)
}

func Warnf(format string, args ...any) {
	defaultLogger.Warnf(format, args...)
}

func Error(message string) {
	defaultLogger.Error(message)
}

func Errorf(format string, args ...any) {
	defaultLogger.Errorf(format, args...)
}

func Fatal(message string) {
	defaultLogger.Fatal(message)
}

func Fatalf(format string, args ...any) {
	defaultLogger.Fatalf(format, args...)
}