from __future__ import annotations

LANG_MAP = {
    "zh-cn": "zh",
    "zh-tw": "zh",
    "zh-hk": "zh",
    "en-us": "en",
    "en-gb": "en",
    "ja-jp": "ja",
    "ko-kr": "ko",
    "fr-fr": "fr",
    "de-de": "de",
    "es-es": "es",
}

WELCOME_MESSAGES = {
    "zh": "👋 欢迎使用！发送消息开始对话。",
    "en": "👋 Welcome! Send a message to start a conversation.",
    "ja": "👋 ようこそ！メッセージを送信して会話を始めてください。",
    "ko": "👋 환영합니다! 메시지를 별내 대화를 시작하세요.",
    "fr": "👋 Bienvenue ! Envoyez un message pour commencer une conversation.",
    "de": "👋 Willkommen! Senden Sie eine Nachricht, um eine Unterhaltung zu beginnen.",
    "es": "👋 ¡Bienvenido! Envíe un mensaje para iniciar una conversación.",
}

ERROR_MESSAGES = {
    "zh": "抱歉，处理请求时出错: {error}",
    "en": "Sorry, an error occurred processing your request: {error}",
}


def normalize_locale(locale: str | None) -> str:
    if not locale:
        return "en"
    locale = locale.lower()
    return LANG_MAP.get(locale, locale[:2] if len(locale) >= 2 else "en")


def get_localized(key: str, locale: str | None, messages: dict, default_lang: str = "en") -> str:
    lang = normalize_locale(locale)
    return messages.get(lang, messages.get(default_lang, ""))