package main

import (
	"log/slog"
	"os"
	"strings"
)

// newLogger builds the process logger from the environment: LOG_LEVEL
// (debug|info|warn|error, default info) and LOG_FORMAT (text|json, default
// text). It writes to stderr with UTC timestamps (matching the previous
// log.LUTC behaviour). Built from getenv directly — not Config — so it exists
// before LoadConfig (the generate-registration path logs before config loads).
func newLogger() *slog.Logger {
	opts := &slog.HandlerOptions{
		Level: parseLogLevel(getenv("LOG_LEVEL", "info")),
		ReplaceAttr: func(_ []string, a slog.Attr) slog.Attr {
			if a.Key == slog.TimeKey && a.Value.Kind() == slog.KindTime {
				a.Value = slog.TimeValue(a.Value.Time().UTC())
			}
			return a
		},
	}
	var h slog.Handler
	if strings.EqualFold(strings.TrimSpace(getenv("LOG_FORMAT", "text")), "json") {
		h = slog.NewJSONHandler(os.Stderr, opts)
	} else {
		h = slog.NewTextHandler(os.Stderr, opts)
	}
	return slog.New(h)
}

func parseLogLevel(s string) slog.Level {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "debug":
		return slog.LevelDebug
	case "warn", "warning":
		return slog.LevelWarn
	case "error":
		return slog.LevelError
	default:
		return slog.LevelInfo
	}
}