// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package speech

import (
	"os"
	"sort"
	"strings"
)

// LocaleVoices prefers the current locale's exact dialect, then its base
// language. An unknown locale retains the catalog, matching quick settings.
func LocaleVoices(voices []Voice) []Voice {
	locale := ""
	for _, key := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
		if value := os.Getenv(key); value != "" {
			locale = value
			break
		}
	}
	normalize := func(value string) string {
		value = strings.Split(strings.Split(value, ".")[0], "@")[0]
		return strings.ToLower(strings.ReplaceAll(value, "_", "-"))
	}
	locale = normalize(locale)
	if locale == "" || locale == "c" || locale == "posix" {
		locale = "en-us"
	}
	for _, language := range []string{locale, strings.SplitN(locale, "-", 2)[0]} {
		var selected []Voice
		for _, voice := range voices {
			if normalize(voice.Language) == language {
				selected = append(selected, voice)
			}
		}
		if len(selected) == 0 {
			continue
		}
		// A '+' in the synthesis name denotes an eSpeak variant; Variant
		// is gender metadata and cannot identify the unmodified voice.
		sort.SliceStable(selected, func(i, j int) bool {
			return !strings.Contains(selected[i].Name, "+") && strings.Contains(selected[j].Name, "+")
		})
		return selected
	}
	return voices
}