import re
import sys
import hmac
import json
import asyncio
from typing import Any, Dict, Union, Optional, TYPE_CHECKING

import httpx
from nonebot.log import logger
from nonebot.config import Config
from nonebot.typing import overrides
from nonebot.message import handle_event
from nonebot.adapters import Bot as BaseBot
from nonebot.exception import RequestDenied

from .utils import log, escape
from .message import Message, MessageSegment
from .event import Reply, Event, MessageEvent, get_event_model
from .exception import NetworkError, ApiNotAvailable, ActionFailed

if TYPE_CHECKING:
    from nonebot.drivers import Driver, WebSocket


def get_auth_bearer(access_token: Optional[str] = None) -> Optional[str]:
    if not access_token:
        return None
    scheme, _, param = access_token.partition(" ")
    if scheme.lower() not in ["bearer", "token"]:
        raise RequestDenied(401, "Not authenticated")
    return param


async def _check_reply(bot: "Bot", event: "Event"):
    """
    :说明:

      检查消息中存在的回复，去除并赋值 ``event.reply``, ``event.to_me``

    :参数:

      * ``bot: Bot``: Bot 对象
      * ``event: Event``: Event 对象
    """
    if not isinstance(event, MessageEvent):
        return

    try:
        index = list(map(lambda x: x.type == "reply",
                         event.message)).index(True)
    except ValueError:
        return
    msg_seg = event.message[index]
    event.reply = Reply.parse_obj(await
                                  bot.get_msg(message_id=msg_seg.data["id"]))
    # ensure string comparation
    if str(event.reply.sender.user_id) == str(event.self_id):
        event.to_me = True
    del event.message[index]
    if len(event.message) > index and event.message[index].type == "at":
        del event.message[index]
    if len(event.message) > index and event.message[index].type == "text":
        event.message[index].data["text"] = event.message[index].data[
            "text"].lstrip()
        if not event.message[index].data["text"]:
            del event.message[index]
    if not event.message:
        event.message.append(MessageSegment.text(""))


def _check_at_me(bot: "Bot", event: "Event"):
    """
    :说明:

      检查消息开头或结尾是否存在 @机器人，去除并赋值 ``event.to_me``

    :参数:

      * ``bot: Bot``: Bot 对象
      * ``event: Event``: Event 对象
    """
    if not isinstance(event, MessageEvent):
        return

    if event.message_type == "private":
        event.to_me = True
    else:
        at_me_seg = MessageSegment.at(event.self_id)

        # check the first segment
        if event.message[0] == at_me_seg:
            event.to_me = True
            del event.message[0]
            if event.message and event.message[0].type == "text":
                event.message[0].data["text"] = event.message[0].data[
                    "text"].lstrip()
                if not event.message[0].data["text"]:
                    del event.message[0]
            if event.message and event.message[0] == at_me_seg:
                del event.message[0]
                if event.message and event.message[0].type == "text":
                    event.message[0].data["text"] = event.message[0].data[
                        "text"].lstrip()
                    if not event.message[0].data["text"]:
                        del event.message[0]

        if not event.to_me:
            # check the last segment
            i = -1
            last_msg_seg = event.message[i]
            if last_msg_seg.type == "text" and \
                    not last_msg_seg.data["text"].strip() and \
                    len(event.message) >= 2:
                i -= 1
                last_msg_seg = event.message[i]

            if last_msg_seg == at_me_seg:
                event.to_me = True
                del event.message[i:]

        if not event.message:
            event.message.append(MessageSegment.text(""))


def _check_nickname(bot: "Bot", event: "Event"):
    """
    :说明:

      检查消息开头是否存在，去除并赋值 ``event.to_me``

    :参数:

      * ``bot: Bot``: Bot 对象
      * ``event: Event``: Event 对象
    """
    if not isinstance(event, MessageEvent):
        return

    first_msg_seg = event.message[0]
    if first_msg_seg.type != "text":
        return

    first_text = first_msg_seg.data["text"]

    nicknames = set(filter(lambda n: n, bot.config.nickname))
    if nicknames:
        # check if the user is calling me with my nickname
        nickname_regex = "|".join(nicknames)
        m = re.search(rf"^({nickname_regex})([\s,，]*|$)", first_text,
                      re.IGNORECASE)
        if m:
            nickname = m.group(1)
            log("DEBUG", f"User is calling me {nickname}")
            event.to_me = True
            first_msg_seg.data["text"] = first_text[m.end():]


def _handle_api_result(result: Optional[Dict[str, Any]]) -> Any:
    """
    :说明:

      处理 API 请求返回值。

    :参数:

      * ``result: Optional[Dict[str, Any]]``: API 返回数据

    :返回:

        - ``Any``: API 调用返回数据

    :异常:

        - ``ActionFailed``: API 调用失败
    """
    if isinstance(result, dict):
        if result.get("status") == "failed":
            raise ActionFailed(**result)
        return result.get("data")


class ResultStore:
    _seq = 1
    _futures: Dict[int, asyncio.Future] = {}

    @classmethod
    def get_seq(cls) -> int:
        s = cls._seq
        cls._seq = (cls._seq + 1) % sys.maxsize
        return s

    @classmethod
    def add_result(cls, result: Dict[str, Any]):
        if isinstance(result.get("echo"), dict) and \
                isinstance(result["echo"].get("seq"), int):
            future = cls._futures.get(result["echo"]["seq"])
            if future:
                future.set_result(result)

    @classmethod
    async def fetch(cls, seq: int, timeout: Optional[float]) -> Dict[str, Any]:
        future = asyncio.get_event_loop().create_future()
        cls._futures[seq] = future
        try:
            return await asyncio.wait_for(future, timeout)
        except asyncio.TimeoutError:
            raise NetworkError("WebSocket API call timeout") from None
        finally:
            del cls._futures[seq]


class Bot(BaseBot):
    """
    CQHTTP 协议 Bot 适配。继承属性参考 `BaseBot <./#class-basebot>`_ 。
    """

    def __init__(self,
                 driver: "Driver",
                 connection_type: str,
                 config: Config,
                 self_id: str,
                 *,
                 websocket: Optional["WebSocket"] = None):

        super().__init__(driver,
                         connection_type,
                         config,
                         self_id,
                         websocket=websocket)

    @property
    @overrides(BaseBot)
    def type(self) -> str:
        """
        - 返回: ``"cqhttp"``
        """
        return "cqhttp"

    @classmethod
    @overrides(BaseBot)
    async def check_permission(cls, driver: "Driver", connection_type: str,
                               headers: dict, body: Optional[dict]) -> str:
        """
        :说明:

          CQHTTP (OneBot) 协议鉴权。参考 `鉴权 <https://github.com/howmanybots/onebot/blob/master/v11/specs/communication/authorization.md>`_
        """
        x_self_id = headers.get("x-self-id")
        x_signature = headers.get("x-signature")
        token = get_auth_bearer(headers.get("authorization"))

        # 检查连接方式
        if connection_type not in ["http", "websocket"]:
            log("WARNING", "Unsupported connection type")
            raise RequestDenied(405, "Unsupported connection type")

        # 检查self_id
        if not x_self_id:
            log("WARNING", "Missing X-Self-ID Header")
            raise RequestDenied(400, "Missing X-Self-ID Header")

        # 检查签名
        secret = driver.config.secret
        if secret and connection_type == "http":
            if not x_signature:
                log("WARNING", "Missing Signature Header")
                raise RequestDenied(401, "Missing Signature")
            sig = hmac.new(secret.encode("utf-8"),
                           json.dumps(body).encode(), "sha1").hexdigest()
            if x_signature != "sha1=" + sig:
                log("WARNING", "Signature Header is invalid")
                raise RequestDenied(403, "Signature is invalid")

        access_token = driver.config.access_token
        if access_token and access_token != token:
            log(
                "WARNING", "Authorization Header is invalid"
                if token else "Missing Authorization Header")
            raise RequestDenied(
                403, "Authorization Header is invalid"
                if token else "Missing Authorization Header")
        return str(x_self_id)

    @overrides(BaseBot)
    async def handle_message(self, message: dict):
        """
        :说明:

          调用 `_check_reply <#async-check-reply-bot-event>`_, `_check_at_me <#check-at-me-bot-event>`_, `_check_nickname <#check-nickname-bot-event>`_ 处理事件并转换为 `Event <#class-event>`_
        """
        if not message:
            return

        if "post_type" not in message:
            ResultStore.add_result(message)
            return

        try:
            post_type = message['post_type']
            detail_type = message.get(f"{post_type}_type")
            detail_type = f".{detail_type}" if detail_type else ""
            sub_type = message.get("sub_type")
            sub_type = f".{sub_type}" if sub_type else ""
            models = get_event_model(post_type + detail_type + sub_type)
            for model in models:
                try:
                    event = model.parse_obj(message)
                    break
                except Exception as e:
                    log("DEBUG", "Event Parser Error", e)
            else:
                event = Event.parse_obj(message)

            # Check whether user is calling me
            await _check_reply(self, event)
            _check_at_me(self, event)
            _check_nickname(self, event)

            await handle_event(self, event)
        except Exception as e:
            logger.opt(colors=True, exception=e).error(
                f"<r><bg #f8bbd0>Failed to handle event. Raw: {message}</bg #f8bbd0></r>"
            )

    @overrides(BaseBot)
    async def call_api(self, api: str, **data) -> Any:
        """
        :说明:

          调用 CQHTTP 协议 API

        :参数:

          * ``api: str``: API 名称
          * ``**data: Any``: API 参数

        :返回:

          - ``Any``: API 调用返回数据

        :异常:

          - ``NetworkError``: 网络错误
          - ``ActionFailed``: API 调用失败
        """
        if "self_id" in data:
            self_id = data.pop("self_id")
            if self_id:
                bot = self.driver.bots[str(self_id)]
                return await bot.call_api(api, **data)

        log("DEBUG", f"Calling API <y>{api}</y>")
        if self.connection_type == "websocket":
            seq = ResultStore.get_seq()
            await self.websocket.send({
                "action": api,
                "params": data,
                "echo": {
                    "seq": seq
                }
            })
            return _handle_api_result(await ResultStore.fetch(
                seq, self.config.api_timeout))

        elif self.connection_type == "http":
            api_root = self.config.api_root.get(self.self_id)
            if not api_root:
                raise ApiNotAvailable
            elif not api_root.endswith("/"):
                api_root += "/"

            headers = {}
            if self.config.access_token is not None:
                headers["Authorization"] = "Bearer " + self.config.access_token

            try:
                async with httpx.AsyncClient(headers=headers) as client:
                    response = await client.post(
                        api_root + api,
                        json=data,
                        timeout=self.config.api_timeout)

                if 200 <= response.status_code < 300:
                    result = response.json()
                    return _handle_api_result(result)
                raise NetworkError(f"HTTP request received unexpected "
                                   f"status code: {response.status_code}")
            except httpx.InvalidURL:
                raise NetworkError("API root url invalid")
            except httpx.HTTPError:
                raise NetworkError("HTTP request failed")

    @overrides(BaseBot)
    async def send(self,
                   event: Event,
                   message: Union[str, Message, MessageSegment],
                   at_sender: bool = False,
                   **kwargs) -> Any:
        """
        :说明:

          根据 ``event``  向触发事件的主体发送消息。

        :参数:

          * ``event: Event``: Event 对象
          * ``message: Union[str, Message, MessageSegment]``: 要发送的消息
          * ``at_sender: bool``: 是否 @ 事件主体
          * ``**kwargs``: 覆盖默认参数

        :返回:

          - ``Any``: API 调用返回数据

        :异常:

          - ``ValueError``: 缺少 ``user_id``, ``group_id``
          - ``NetworkError``: 网络错误
          - ``ActionFailed``: API 调用失败
        """
        message = escape(message) if isinstance(message, str) else message
        msg = message if isinstance(message, Message) else Message(message)

        at_sender = at_sender and getattr(event, "user_id", None)

        params = {}
        if getattr(event, "user_id", None):
            params["user_id"] = getattr(event, "user_id")
        if getattr(event, "group_id", None):
            params["group_id"] = getattr(event, "group_id")
        params.update(kwargs)

        if "message_type" not in params:
            if params.get("group_id", None):
                params["message_type"] = "group"
            elif params.get("user_id", None):
                params["message_type"] = "private"
            else:
                raise ValueError("Cannot guess message type to reply!")

        if at_sender and params["message_type"] != "private":
            params["message"] = MessageSegment.at(params["user_id"]) + \
                MessageSegment.text(" ") + msg
        else:
            params["message"] = msg
        return await self.send_msg(**params)