from fastapi import APIRouter, Request, Response

from app.wechat.handler import WeChatMessageHandler

router = APIRouter()

_handler: WeChatMessageHandler | None = None


def get_handler() -> WeChatMessageHandler:
    global _handler
    if _handler is None:
        _handler = WeChatMessageHandler()
    return _handler


@router.get("/wechat/callback")
async def wechat_verify(request: Request):
    handler = get_handler()
    params = request.query_params
    echostr = handler.verify_url(
        params.get("msg_signature", ""),
        params.get("timestamp", ""),
        params.get("nonce", ""),
        params.get("echostr", ""),
    )
    if echostr:
        return Response(content=echostr, media_type="text/plain")
    return Response(content="verification failed", status_code=403)


@router.post("/wechat/callback")
async def wechat_callback(request: Request):
    handler = get_handler()
    params = request.query_params
    post_data = await request.body()
    post_text = post_data.decode("utf-8")

    xml_tree = handler.decrypt_message(
        post_text,
        params.get("msg_signature", ""),
        params.get("timestamp", ""),
        params.get("nonce", ""),
    )
    if xml_tree is None:
        return Response(content="decrypt failed", status_code=403)

    msg_type = xml_tree.find("MsgType")
    msg_type = msg_type.text if msg_type is not None else "unknown"

    if msg_type == "event":
        event = xml_tree.find("Event")
        event_key = xml_tree.find("EventKey")
        from_user = xml_tree.find("FromUserName")
        await handler.handle_event(
            event.text if event is not None else "",
            event_key.text if event_key is not None else None,
            from_user.text if from_user is not None else "",
        )
    elif msg_type == "text":
        content = xml_tree.find("Content")
        from_user = xml_tree.find("FromUserName")
        await handler.handle_text(
            content.text if content is not None else "",
            from_user.text if from_user is not None else "",
        )

    return Response(content="success")