grokkit/internal/logger/logger.go

package logger

import (
	"context"
	"io"
	"log/slog"
	"os"
	"path/filepath"
)

var (
	logger *slog.Logger
	level  = new(slog.LevelVar) // Allows dynamic level changes
)

// Init initializes the logger with the specified log level
func Init(logLevel string) error {
	home, err := os.UserHomeDir()
	if err != nil {
		home = "."
	}

	logDir := filepath.Join(home, ".config", "grokkit")
	if err := os.MkdirAll(logDir, 0750); err != nil {
		return err
	}

	logFile := filepath.Join(logDir, "grokkit.log")
	file, err := os.OpenFile(logFile, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0600)
	if err != nil {
		return err
	}

	// Parse log level
	switch logLevel {
	case "debug":
		level.Set(slog.LevelDebug)
	case "info":
		level.Set(slog.LevelInfo)
	case "warn":
		level.Set(slog.LevelWarn)
	case "error":
		level.Set(slog.LevelError)
	default:
		level.Set(slog.LevelInfo)
	}

	// Create multi-writer for both file and stderr (if debug)
	var w io.Writer = file
	if logLevel == "debug" {
		w = io.MultiWriter(file, os.Stderr)
	}

	// Use JSON handler for structured logging
	handler := slog.NewJSONHandler(w, &slog.HandlerOptions{
		Level: level,
	})

	logger = slog.New(handler)
	slog.SetDefault(logger)

	return nil
}

// SetLevel changes the log level dynamically
func SetLevel(logLevel string) {
	switch logLevel {
	case "debug":
		level.Set(slog.LevelDebug)
	case "info":
		level.Set(slog.LevelInfo)
	case "warn":
		level.Set(slog.LevelWarn)
	case "error":
		level.Set(slog.LevelError)
	}
}

// Debug logs at debug level with structured fields
func Debug(msg string, args ...any) {
	if logger != nil {
		logger.Debug(msg, args...)
	}
}

// Info logs at info level with structured fields
func Info(msg string, args ...any) {
	if logger != nil {
		logger.Info(msg, args...)
	}
}

// Warn logs at warn level with structured fields
func Warn(msg string, args ...any) {
	if logger != nil {
		logger.Warn(msg, args...)
	}
}

// Error logs at error level with structured fields
func Error(msg string, args ...any) {
	if logger != nil {
		logger.Error(msg, args...)
	}
}

// With returns a logger with additional context fields
func With(args ...any) *slog.Logger {
	if logger != nil {
		return logger.With(args...)
	}
	return slog.Default()
}

// WithContext returns a logger with values from context
func WithContext(ctx context.Context) *slog.Logger {
	if logger != nil {
		return logger.With(slog.Any("context", ctx))
	}
	return slog.Default()
}