# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
import json
import logging
import uuid
from typing import Any, Dict, List, Optional, Tuple

import jwt
import redis
from flask import Flask, g, request, Request, Response, session

logger = logging.getLogger(__name__)


class AsyncQueryTokenException(Exception):
    pass


class AsyncQueryJobException(Exception):
    pass


def build_job_metadata(
    channel_id: str, job_id: str, user_id: Optional[str], **kwargs: Any
) -> Dict[str, Any]:
    return {
        "channel_id": channel_id,
        "job_id": job_id,
        "user_id": int(user_id) if user_id else None,
        "status": kwargs.get("status"),
        "errors": kwargs.get("errors", []),
        "result_url": kwargs.get("result_url"),
    }


def parse_event(event_data: Tuple[str, Dict[str, Any]]) -> Dict[str, Any]:
    event_id = event_data[0]
    event_payload = event_data[1]["data"]
    return {"id": event_id, **json.loads(event_payload)}


def increment_id(redis_id: str) -> str:
    # redis stream IDs are in this format: '1607477697866-0'
    try:
        prefix, last = redis_id[:-1], int(redis_id[-1])
        return prefix + str(last + 1)
    except Exception:  # pylint: disable=broad-except
        return redis_id


class AsyncQueryManager:
    # pylint: disable=too-many-instance-attributes

    MAX_EVENT_COUNT = 100
    STATUS_PENDING = "pending"
    STATUS_RUNNING = "running"
    STATUS_ERROR = "error"
    STATUS_DONE = "done"

    def __init__(self) -> None:
        super().__init__()
        self._redis: redis.Redis
        self._stream_prefix: str = ""
        self._stream_limit: Optional[int]
        self._stream_limit_firehose: Optional[int]
        self._jwt_cookie_name: str
        self._jwt_cookie_secure: bool = False
        self._jwt_cookie_domain: Optional[str]
        self._jwt_secret: str

    def init_app(self, app: Flask) -> None:
        config = app.config
        if (
            config["CACHE_CONFIG"]["CACHE_TYPE"] == "null"
            or config["DATA_CACHE_CONFIG"]["CACHE_TYPE"] == "null"
        ):
            raise Exception(
                """
                Cache backends (CACHE_CONFIG, DATA_CACHE_CONFIG) must be configured
                and non-null in order to enable async queries
                """
            )

        if len(config["GLOBAL_ASYNC_QUERIES_JWT_SECRET"]) < 32:
            raise AsyncQueryTokenException(
                "Please provide a JWT secret at least 32 bytes long"
            )

        self._redis = redis.Redis(  # type: ignore
            **config["GLOBAL_ASYNC_QUERIES_REDIS_CONFIG"], decode_responses=True
        )
        self._stream_prefix = config["GLOBAL_ASYNC_QUERIES_REDIS_STREAM_PREFIX"]
        self._stream_limit = config["GLOBAL_ASYNC_QUERIES_REDIS_STREAM_LIMIT"]
        self._stream_limit_firehose = config[
            "GLOBAL_ASYNC_QUERIES_REDIS_STREAM_LIMIT_FIREHOSE"
        ]
        self._jwt_cookie_name = config["GLOBAL_ASYNC_QUERIES_JWT_COOKIE_NAME"]
        self._jwt_cookie_secure = config["GLOBAL_ASYNC_QUERIES_JWT_COOKIE_SECURE"]
        self._jwt_cookie_domain = config["GLOBAL_ASYNC_QUERIES_JWT_COOKIE_DOMAIN"]
        self._jwt_secret = config["GLOBAL_ASYNC_QUERIES_JWT_SECRET"]

        @app.after_request
        def validate_session(  # pylint: disable=unused-variable
            response: Response,
        ) -> Response:
            user_id = None

            try:
                user_id = g.user.get_id()
                user_id = int(user_id)
            except Exception:  # pylint: disable=broad-except
                pass

            reset_token = (
                not request.cookies.get(self._jwt_cookie_name)
                or "async_channel_id" not in session
                or "async_user_id" not in session
                or user_id != session["async_user_id"]
            )

            if reset_token:
                async_channel_id = str(uuid.uuid4())
                session["async_channel_id"] = async_channel_id
                session["async_user_id"] = user_id

                sub = str(user_id) if user_id else None
                token = self.generate_jwt({"channel": async_channel_id, "sub": sub})

                response.set_cookie(
                    self._jwt_cookie_name,
                    value=token,
                    httponly=True,
                    secure=self._jwt_cookie_secure,
                    domain=self._jwt_cookie_domain,
                )

            return response

    def generate_jwt(self, data: Dict[str, Any]) -> str:
        encoded_jwt = jwt.encode(data, self._jwt_secret, algorithm="HS256")
        return encoded_jwt.decode("utf-8")

    def parse_jwt(self, token: str) -> Dict[str, Any]:
        data = jwt.decode(token, self._jwt_secret, algorithms=["HS256"])
        return data

    def parse_jwt_from_request(self, req: Request) -> Dict[str, Any]:
        token = req.cookies.get(self._jwt_cookie_name)
        if not token:
            raise AsyncQueryTokenException("Token not preset")

        try:
            return self.parse_jwt(token)
        except Exception as exc:
            logger.warning(exc)
            raise AsyncQueryTokenException("Failed to parse token")

    def init_job(self, channel_id: str, user_id: Optional[str]) -> Dict[str, Any]:
        job_id = str(uuid.uuid4())
        return build_job_metadata(
            channel_id, job_id, user_id, status=self.STATUS_PENDING
        )

    def read_events(
        self, channel: str, last_id: Optional[str]
    ) -> List[Optional[Dict[str, Any]]]:
        stream_name = f"{self._stream_prefix}{channel}"
        start_id = increment_id(last_id) if last_id else "-"
        results = self._redis.xrange(  # type: ignore
            stream_name, start_id, "+", self.MAX_EVENT_COUNT
        )
        return [] if not results else list(map(parse_event, results))

    def update_job(
        self, job_metadata: Dict[str, Any], status: str, **kwargs: Any
    ) -> None:
        if "channel_id" not in job_metadata:
            raise AsyncQueryJobException("No channel ID specified")

        if "job_id" not in job_metadata:
            raise AsyncQueryJobException("No job ID specified")

        updates = {"status": status, **kwargs}
        event_data = {"data": json.dumps({**job_metadata, **updates})}

        full_stream_name = f"{self._stream_prefix}full"
        scoped_stream_name = f"{self._stream_prefix}{job_metadata['channel_id']}"

        logger.debug("********** logging event data to stream %s", scoped_stream_name)
        logger.debug(event_data)

        self._redis.xadd(  # type: ignore
            scoped_stream_name, event_data, "*", self._stream_limit
        )
        self._redis.xadd(  # type: ignore
            full_stream_name, event_data, "*", self._stream_limit_firehose
        )
