from __future__ import annotations

import zlib
from base64 import b64decode, b64encode
from datetime import datetime, timezone
from enum import Enum
from typing import Any

from redis import Redis

from .defaults import UNSERIALIZABLE_RETURN_VALUE_PAYLOAD
from .job import Job
from .serializers import resolve_serializer
from .utils import decode_redis_hash, now


def get_key(job_id):
    return f'rq:results:{job_id}'


class Result:
    class Type(Enum):
        SUCCESSFUL = 1
        FAILED = 2
        STOPPED = 3
        RETRIED = 4
        MAX_RETRIES_EXCEEDED = 5

    def __init__(
        self,
        job_id: str,
        type: Type,
        connection: Redis,
        id: str | None = None,
        created_at: datetime | None = None,
        return_value: Any | None = None,
        exc_string: str | None = None,
        worker_name: str = '',
        serializer=None,
        execution_id: str | None = None,
        execution_started_at: datetime | None = None,
        execution_ended_at: datetime | None = None,
    ):
        self.return_value = return_value
        self.exc_string = exc_string
        self.type = type
        self.created_at = created_at if created_at else now()
        self.serializer = resolve_serializer(serializer)
        self.connection = connection
        self.job_id = job_id
        self.id = id
        self.worker_name = worker_name
        self.execution_id = execution_id
        self.execution_started_at = execution_started_at
        self.execution_ended_at = execution_ended_at

    def __repr__(self):
        return f'Result(id={self.id}, type={self.Type(self.type).name})'

    def __eq__(self, other):
        try:
            return self.id == other.id
        except AttributeError:
            return False

    def __bool__(self):
        return bool(self.id)

    @classmethod
    def create(
        cls,
        job,
        type,
        ttl,
        return_value=None,
        exc_string=None,
        worker_name='',
        pipeline=None,
        execution_id: str | None = None,
        execution_started_at: datetime | None = None,
        execution_ended_at: datetime | None = None,
    ) -> Result:
        result = cls(
            job_id=job.id,
            type=type,
            connection=job.connection,
            return_value=return_value,
            exc_string=exc_string,
            worker_name=worker_name,
            serializer=job.serializer,
            execution_id=execution_id,
            execution_started_at=execution_started_at,
            execution_ended_at=execution_ended_at,
        )
        result.save(ttl=ttl, pipeline=pipeline)
        return result

    @classmethod
    def create_failure(
        cls,
        job,
        ttl,
        exc_string,
        worker_name='',
        pipeline=None,
        execution_id: str | None = None,
        execution_started_at: datetime | None = None,
        execution_ended_at: datetime | None = None,
    ) -> Result:
        result = cls(
            job_id=job.id,
            type=cls.Type.FAILED,
            connection=job.connection,
            exc_string=exc_string,
            worker_name=worker_name,
            serializer=job.serializer,
            execution_id=execution_id,
            execution_started_at=execution_started_at,
            execution_ended_at=execution_ended_at,
        )
        result.save(ttl=ttl, pipeline=pipeline)
        return result

    @classmethod
    def create_retried(
        cls,
        job,
        ttl,
        return_value,
        worker_name,
        execution_id: str,
        execution_started_at: datetime,
        execution_ended_at: datetime,
        pipeline=None,
    ) -> Result:
        return cls.create(
            job,
            cls.Type.RETRIED,
            ttl,
            return_value=return_value,
            worker_name=worker_name,
            pipeline=pipeline,
            execution_id=execution_id,
            execution_started_at=execution_started_at,
            execution_ended_at=execution_ended_at,
        )

    @classmethod
    def create_max_retries_exceeded(
        cls,
        job,
        ttl,
        return_value,
        worker_name,
        execution_id: str,
        execution_started_at: datetime,
        execution_ended_at: datetime,
        pipeline=None,
    ) -> Result:
        return cls.create(
            job,
            cls.Type.MAX_RETRIES_EXCEEDED,
            ttl,
            return_value=return_value,
            worker_name=worker_name,
            pipeline=pipeline,
            execution_id=execution_id,
            execution_started_at=execution_started_at,
            execution_ended_at=execution_ended_at,
        )

    @classmethod
    def all(cls, job: Job, serializer=None):
        """Returns all results for job"""
        # response = job.connection.zrange(cls.get_key(job.id), 0, 10, desc=True, withscores=True)
        response = job.connection.xrevrange(cls.get_key(job.id), '+', '-')
        results = []
        for result_id, payload in response:
            results.append(
                cls.restore(job.id, result_id.decode(), payload, connection=job.connection, serializer=serializer)
            )

        return results

    @classmethod
    def count(cls, job: Job) -> int:
        """Returns the number of job results"""
        return job.connection.xlen(cls.get_key(job.id))

    @classmethod
    def delete_all(cls, job: Job) -> None:
        """Delete all job results"""
        job.connection.delete(cls.get_key(job.id))

    @classmethod
    def restore(cls, job_id: str, result_id: str, payload: dict, connection: Redis, serializer=None) -> Result:
        """Create a Result object from given Redis payload"""
        created_at = datetime.fromtimestamp(int(result_id.split('-')[0]) / 1000, tz=timezone.utc)
        payload = decode_redis_hash(payload)
        # data, timestamp = payload
        # result_data = json.loads(data)
        # created_at = datetime.fromtimestamp(timestamp, tz=timezone.utc)

        serializer = resolve_serializer(serializer)
        return_value = payload.get('return_value')
        if return_value is not None:
            return_value = serializer.loads(b64decode(return_value.decode()))

        exc_string = payload.get('exc_string')
        if exc_string:
            exc_string = zlib.decompress(b64decode(exc_string)).decode()

        worker_name = payload.get('worker_name', b'').decode() if payload.get('worker_name') else ''

        execution_id = payload.get('execution_id')
        if execution_id:
            execution_id = execution_id.decode()

        execution_started_at = payload.get('execution_started_at')
        if execution_started_at:
            execution_started_at = datetime.fromtimestamp(float(execution_started_at), tz=timezone.utc)

        execution_ended_at = payload.get('execution_ended_at')
        if execution_ended_at:
            execution_ended_at = datetime.fromtimestamp(float(execution_ended_at), tz=timezone.utc)

        return Result(
            job_id,
            Result.Type(int(payload['type'])),
            connection=connection,
            id=result_id,
            created_at=created_at,
            return_value=return_value,
            exc_string=exc_string,
            worker_name=worker_name,
            execution_id=execution_id,
            execution_started_at=execution_started_at,
            execution_ended_at=execution_ended_at,
        )

    @classmethod
    def fetch(cls, job: Job, serializer=None) -> Result | None:
        """Fetch a result that matches a given job ID. The current sorted set
        based implementation does not allow us to fetch a given key by ID
        so we need to iterate through results, deserialize the payload and
        look for a matching ID.

        Future Redis streams based implementation may make this more efficient
        and scalable.
        """
        return None

    @classmethod
    def fetch_latest(cls, job: Job, serializer=None, timeout: int = 0) -> Result | None:
        """Returns the latest result for given job instance or ID.

        If a non-zero timeout is provided, block for a result until timeout is reached.
        """
        if timeout:
            # Unlike blpop, xread timeout is in miliseconds. "0-0" is the special value for the
            # first item in the stream, like '-' for xrevrange.
            timeout_ms = timeout * 1000
            response = job.connection.xread({cls.get_key(job.id): '0-0'}, block=timeout_ms)
            if not response:
                return None
            response = response[0]  # Querying single stream only.
            response = response[1]  # Xread also returns Result.id, which we don't need.
            result_id, payload = response[-1]  # Take most recent result.

        else:
            # If not blocking, use xrevrange to load a single result (as xread will load them all).
            response = job.connection.xrevrange(cls.get_key(job.id), '+', '-', count=1)
            if not response:
                return None
            result_id, payload = response[0]

        res = cls.restore(job.id, result_id.decode(), payload, connection=job.connection, serializer=serializer)
        return res

    @classmethod
    def get_key(cls, job_id):
        return f'rq:results:{job_id}'

    def save(self, ttl, pipeline=None):
        """Save result data to Redis"""
        key = self.get_key(self.job_id)

        connection = pipeline if pipeline is not None else self.connection
        # result = connection.zadd(key, {self.serialize(): self.created_at.timestamp()})
        result = connection.xadd(key, self.serialize(), maxlen=10)
        # If xadd() is called in a pipeline, it returns a pipeline object instead of stream ID
        if pipeline is None:
            self.id = result.decode()
        if ttl is not None:
            if ttl == -1:
                connection.persist(key)
            else:
                connection.expire(key, ttl)
        return self.id

    def serialize(self) -> dict[str, Any]:
        data: dict[str, Any] = {'type': self.type.value, 'worker_name': self.worker_name}

        if self.exc_string is not None:
            data['exc_string'] = b64encode(zlib.compress(self.exc_string.encode())).decode()

        try:
            serialized = self.serializer.dumps(self.return_value)
        except:  # noqa
            serialized = self.serializer.dumps(UNSERIALIZABLE_RETURN_VALUE_PAYLOAD)

        if self.return_value is not None:
            data['return_value'] = b64encode(serialized).decode()

        if self.execution_id:
            data['execution_id'] = self.execution_id

        if self.execution_started_at:
            data['execution_started_at'] = self.execution_started_at.timestamp()

        if self.execution_ended_at:
            data['execution_ended_at'] = self.execution_ended_at.timestamp()

        # return json.dumps(data)
        return data
