import asyncio
import logging
import xml.etree.ElementTree as ET

from fastapi import APIRouter, Query, Request
from fastapi.responses import PlainTextResponse

from yuxi.channel.extensions.wechat_kf.crypto import WeChatCrypto
from yuxi.channel.extensions.wechat_kf.dedupe import MessageDeduplicator
from yuxi.channel.extensions.wechat_kf.config import WeChatKFConfig
from yuxi.channel.extensions.wechat_kf.gateway import _get_gateway

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/webhook/wechat-kf", tags=["wechat-kf"])

_config = WeChatKFConfig()
_deduplicator = MessageDeduplicator()
_pairing = None


def _get_pairing():
    global _pairing
    if _pairing is None:
        from yuxi.channel.extensions.wechat_kf.pairing import WeChatKFPairing

        _pairing = WeChatKFPairing()
    return _pairing


def _build_crypto() -> WeChatCrypto | None:
    account = _config.resolve_account()
    if not account.is_configured():
        return None
    return WeChatCrypto(
        token=account.token,
        encoding_aes_key=account.encoding_aes_key,
        app_id=account.corp_id,
    )


@router.get("/callback")
async def kf_url_verify(
    msg_signature: str = Query(...),
    timestamp: str = Query(...),
    nonce: str = Query(...),
    echostr: str = Query(...),
):
    crypto = _build_crypto()
    if crypto is None:
        return PlainTextResponse("not configured", status_code=503)

    if not crypto.verify_signature(msg_signature, timestamp, nonce, echostr):
        logger.warning("WeChat KF URL verification failed: invalid signature")
        return PlainTextResponse("signature failed", status_code=403)

    try:
        decoded, _ = crypto.decrypt(echostr)
        return PlainTextResponse(decoded)
    except Exception:
        logger.exception("WeChat KF echostr decryption failed")
        return PlainTextResponse("decrypt failed", status_code=400)


@router.post("/callback")
async def kf_message_callback(
    request: Request,
    msg_signature: str = Query(...),
    timestamp: str = Query(...),
    nonce: str = Query(...),
):
    crypto = _build_crypto()
    if crypto is None:
        return PlainTextResponse("not configured", status_code=503)

    body = await request.body()
    body_str = body.decode("utf-8")

    try:
        root = ET.fromstring(body_str)
        encrypt_el = root.find("Encrypt")
        encrypt = encrypt_el.text or "" if encrypt_el is not None else ""
    except Exception:
        logger.exception("WeChat KF XML parse failed")
        return PlainTextResponse("invalid xml", status_code=400)

    if not crypto.verify_signature(msg_signature, timestamp, nonce, encrypt):
        logger.warning("WeChat KF message callback: invalid msg_signature")
        return PlainTextResponse("signature failed", status_code=403)

    try:
        decrypted_xml, _ = crypto.decrypt(encrypt)
    except Exception:
        logger.exception("WeChat KF message decryption failed")
        return PlainTextResponse("decrypt failed", status_code=403)

    try:
        root = ET.fromstring(decrypted_xml)
    except Exception:
        logger.exception("WeChat KF decrypted XML parse failed")
        return PlainTextResponse("invalid decrypted xml", status_code=400)

    msg_type = root.findtext("MsgType", "")
    event = root.findtext("Event", "")
    open_kfid = root.findtext("OpenKfId", "")
    token = root.findtext("Token", "")

    if msg_type == "event" and event == "kf_msg_or_event":
        asyncio.create_task(_handle_kf_event(open_kfid, token))

    return PlainTextResponse("success")


async def _handle_kf_event(open_kfid: str, token: str):
    gw = _get_gateway()
    if not gw:
        logger.warning("No WeChat KF gateway available for event handling")
        return

    from yuxi.channel.extensions.wechat_kf.sync import sync_messages

    try:
        result = await sync_messages(
            http=gw._http,
            access_token=await gw.get_access_token(),
            open_kfid=open_kfid,
            token=token,
        )
        if result.get("errcode") == 0:
            for msg in result.get("msg_list", []):
                await gw._handle_message(msg)
    except Exception:
        logger.exception("WeChat KF event handling failed for open_kfid=%s", open_kfid)