package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

func normalizedFormat(format string) string {
	f := strings.ToLower(strings.TrimPrefix(format, "."))
	switch f {
	case "m4a", "mp4", "mmp4":
		return "m4a"
	case "mflac", "flac":
		return "flac"
	case "mp3":
		return "mp3"
	case "ogg", "opus":
		return "ogg"
	case "wav":
		return "wav"
	case "aac":
		return "aac"
	default:
		return f
	}
}

func actualQuality(requested, resolved, format string) string {
	f := normalizedFormat(format)
	if f == "flac" {
		if resolved != "" {
			return resolved
		}
		if requested == "lossless" || requested == "hires" {
			return requested
		}
	}
	if f == "mp3" {
		if resolved == "standard" || resolved == "exhigh" || resolved == "sq" {
			return resolved
		}
	}
	return ""
}

func renameToActualFormat(local string, format string) (string, error) {
	ext := normalizedFormat(format)
	if ext == "" {
		return local, nil
	}
	target := strings.TrimSuffix(local, filepath.Ext(local)) + "." + ext
	if target == local {
		return local, nil
	}
	if _, err := os.Stat(target); err == nil {
		if err := os.Remove(local); err != nil {
			return "", err
		}
		return target, nil
	}
	if err := os.Rename(local, target); err != nil {
		return "", fmt.Errorf("rename actual format: %w", err)
	}
	return target, nil
}