minstrel/internal/logging/logging.go

package logging

import (
	"fmt"
	"io"
	"log/slog"
	"strings"
)

func New(w io.Writer, level, format string) (*slog.Logger, error) {
	lvl, err := parseLevel(level)
	if err != nil {
		return nil, err
	}
	opts := &slog.HandlerOptions{Level: lvl}

	var h slog.Handler
	switch strings.ToLower(format) {
	case "", "text":
		h = slog.NewTextHandler(w, opts)
	case "json":
		h = slog.NewJSONHandler(w, opts)
	default:
		return nil, fmt.Errorf("unknown log format %q (want text|json)", format)
	}
	// Errors are also kept for the admin Overview (M504).
	return slog.New(newRingHandler(h, Errors)), nil
}

func parseLevel(s string) (slog.Level, error) {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "", "info":
		return slog.LevelInfo, nil
	case "debug":
		return slog.LevelDebug, nil
	case "warn", "warning":
		return slog.LevelWarn, nil
	case "error":
		return slog.LevelError, nil
	default:
		return 0, fmt.Errorf("unknown log level %q", s)
	}
}