// Package logging configures the process-wide slog logger.
package logging

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

// Options mirrors the logging section of the config file.
type Options struct {
	Level     string
	Format    string
	AddSource bool
}

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

// New builds a logger writing to w. It does not install it as the default.
func New(w io.Writer, opts Options) (*slog.Logger, error) {
	level, err := ParseLevel(opts.Level)
	if err != nil {
		return nil, err
	}
	handlerOpts := &slog.HandlerOptions{Level: level, AddSource: opts.AddSource}

	var h slog.Handler
	switch strings.ToLower(strings.TrimSpace(opts.Format)) {
	case "", "text":
		h = slog.NewTextHandler(w, handlerOpts)
	case "json":
		h = slog.NewJSONHandler(w, handlerOpts)
	default:
		return nil, fmt.Errorf("unknown log format %q", opts.Format)
	}
	return slog.New(h), nil
}