import logging
from telegram import Update
from telegram.ext import Application, ContextTypes, ChatMemberHandler

# 請替換成你的 Bot Token（從 @BotFather 取得）
TOKEN = ""

# 啟用 logging，方便除錯
logging.basicConfig(
    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s", level=logging.INFO
)
logger = logging.getLogger(__name__)

async def my_chat_member_handler(update: Update, context: ContextTypes.DEFAULT_TYPE):
    """
    處理 bot 自身在群組的狀態變化（被加入或移除）
    """
    chat_member_update = update.my_chat_member
    if chat_member_update is None:
        return

    old_status = chat_member_update.old_chat_member.status
    new_status = chat_member_update.new_chat_member.status

    # 偵測 bot 被加入群組
    if old_status in ("left", "kicked", "banned") and new_status in ("member", "administrator", "creator"):
        chat = chat_member_update.chat

        # 只處理群組或超級群組
        if chat.type in ("group", "supergroup"):
            group_title = chat.title or "未知群組名稱"
            group_id = chat.id

            # 取得把 bot 拉進群組的人
            adder = chat_member_update.from_user
            adder_name = adder.full_name or adder.username or "未知使用者"

            message = (
                f"謝謝你把我拉進新群組！\n\n"
                f"群組名稱：{group_title}\n"
                f"群組 ID：{group_id}"
            )

            # 私訊給拉 bot 的人
            try:
                await context.bot.send_message(chat_id=adder.id, text=message)
                logger.info(f"已成功私訊群組資訊給 {adder_name} ({adder.id})")
            except Exception as e:
                logger.error(f"無法私訊給 {adder_name} ({adder.id}): {e}")
                # 常見原因：對方還沒和 bot 開啟私人對話（先跟 bot 說 hi 就能解決）

def main():
    """啟動 Bot"""
    application = Application.builder().token(TOKEN).build()

    # 正確註冊：第二個參數直接傳 ChatMemberHandler.MY_CHAT_MEMBER
    application.add_handler(
        ChatMemberHandler(my_chat_member_handler, ChatMemberHandler.MY_CHAT_MEMBER)
    )

    print("Bot 正在啟動...")
    print("把 Bot 拉進任何群組，即可測試功能（你會收到私訊包含群組名稱與 ID）")
    application.run_polling(allowed_updates=Update.ALL_TYPES)

if __name__ == "__main__":
    main()