import xml.etree.cElementTree as ET
from typing import Optional

from app.wechat.crypto import WXBizMsgCrypt
from app.config import settings


class WeChatMessageHandler:
    def __init__(self):
        self.wxcpt = WXBizMsgCrypt(
            sToken=settings.wechat_token,
            sEncodingAESKey=settings.wechat_encoding_aes_key,
            sReceiveId=settings.wechat_corp_id,
        )

    def verify_url(
        self, msg_signature: str, timestamp: str, nonce: str, echostr: str
    ) -> Optional[str]:
        ret, sEchoStr = self.wxcpt.VerifyURL(
            msg_signature, timestamp, nonce, echostr
        )
        if ret == 0:
            return (
                sEchoStr.decode("utf-8")
                if isinstance(sEchoStr, bytes)
                else sEchoStr
            )
        return None

    def decrypt_message(
        self,
        post_data: str,
        msg_signature: str,
        timestamp: str,
        nonce: str,
    ) -> Optional[ET.Element]:
        ret, xml_content = self.wxcpt.DecryptMsg(
            post_data, msg_signature, timestamp, nonce
        )
        if ret != 0:
            return None
        return ET.fromstring(xml_content)

    def encrypt_response(
        self, response_xml: str, nonce: str, timestamp: str
    ) -> Optional[str]:
        ret, encrypted = self.wxcpt.EncryptMsg(response_xml, nonce, timestamp)
        if ret == 0:
            return encrypted
        return None

    def handle_event(
        self, event: str, event_key: Optional[str], from_user: str
    ) -> Optional[str]:
        return None

    def handle_text(self, content: str, from_user: str) -> Optional[str]:
        return None