package logger

import (
	"fmt"
	"log"
	"strings"
)

// Level represents the logging verbosity level.
type Level int

const (
	LevelDebug Level = iota
	LevelInfo
	LevelWarn
)

var currentLevel = LevelInfo

// SetLevel sets the global log level from a string: "debug", "info", or "warn".
func SetLevel(s string) {
	switch strings.ToLower(s) {
	case "debug":
		currentLevel = LevelDebug
	case "info":
		currentLevel = LevelInfo
	case "warn":
		currentLevel = LevelWarn
	default:
		currentLevel = LevelInfo
	}
}

// Debug logs a message only when LOG_LEVEL=debug.
func Debug(format string, args ...interface{}) {
	if currentLevel <= LevelDebug {
		log.Printf(format, args...)
	}
}

// Info logs a message when LOG_LEVEL is debug or info.
func Info(format string, args ...interface{}) {
	if currentLevel <= LevelInfo {
		log.Printf(format, args...)
	}
}

// Warn logs a message at any log level (always visible).
func Warn(format string, args ...interface{}) {
	if currentLevel <= LevelWarn {
		log.Printf(format, args...)
	}
}

// Fatal logs and exits. Always visible regardless of level.
func Fatal(format string, args ...interface{}) {
	log.Fatalf(format, args...)
}

// formatKV formats key=value pairs for structured console output.
func formatKV(pairs ...interface{}) string {
	if len(pairs)%2 != 0 {
		return fmt.Sprint(pairs...)
	}
	var b strings.Builder
	for i := 0; i < len(pairs); i += 2 {
		if i > 0 {
			b.WriteString(" | ")
		}
		b.WriteString(fmt.Sprintf("%v=%v", pairs[i], pairs[i+1]))
	}
	return b.String()
}