import redis

import json

import os

import pkg_resources

import sys

import numpy as np

import msgpack

import msgpack_numpy as m

m.patch()

import hashlib

import random

from osim.redis import messages

import time

import logging

logger = logging.getLogger(__name__)

logger.setLevel(logging.INFO)

class Client(object):

    """

        Redis client to interface with osim-rl redis-service

        The Docker container hosts a redis-server inside the container.

        This client connects to the same redis-server, and communicates with the service.

        The service eventually will reside outside the docker container, and will communicate

        with the client only via the redis-server of the docker container.

        On the instantiation of the docker container, one service will be instantiated parallely.

        The service will accepts commands at "`service_id`::commands"

        where `service_id` is either provided as an `env` variable or is

        instantiated to "osim_rl_redis_service_id"

    """

    def __init__(self, remote_host='127.0.0.1', remote_port=6379, remote_db=0, remote_password=None, verbose=False):

        self.redis_pool = redis.ConnectionPool(host=remote_host, port=remote_port, db=remote_db, password=remote_password)

        self.namespace = "osim-rl"

        try:

            self.service_id =  os.environ['osim_rl_redis_service_id']

        except KeyError:

            self.service_id = "osim_rl_redis_service_id"

        self.command_channel = "{}::{}::commands".format(self.namespace, self.service_id)

        self.verbose = verbose

        self.ping_pong()

    def get_redis_connection(self):

        return redis.Redis(connection_pool=self.redis_pool)

    def _generate_response_channel(self):

        random_hash = hashlib.md5("{}".format(random.randint(0, 10**10)).encode('utf-8')).hexdigest()

        response_channel = "{}::{}::response::{}".format(   self.namespace,

                                                            self.service_id,

                                                            random_hash)

        return response_channel

    def _blocking_request(self, _request):

        """

            request:

                -command_type

                -payload

                -response_channel

            response: (on response_channel)

                - RESULT

            * Send the payload on command_channel (self.namespace+"::command")

                ** redis-left-push (LPUSH)

            * Keep listening on response_channel (BLPOP)

        """

        assert type(_request) ==type({})

        _request['response_channel'] = self._generate_response_channel()

        _redis = self.get_redis_connection()

        """

            The client always pushes in the left

            and the service always pushes in the right

        """

        if self.verbose: print("Request : ", _response)

        # Push request in command_channels

        payload = msgpack.packb(_request, default=m.encode, use_bin_type=True)

        _redis.lpush(self.command_channel, payload)

        ## TODO: Check if we can use `repr` for json.dumps string serialization

        # Wait with a blocking pop for the response

        _response = _redis.blpop(_request['response_channel'])[1]

        if self.verbose: print("Response : ", _response)

        _response = msgpack.unpackb(_response, object_hook=m.decode, encoding="utf8")

        if _response['type'] == messages.OSIM_RL.ERROR:

            raise Exception(str(_response))

        else:

            return _response

    def ping_pong(self):

        """

            Official Handshake with the grading service

            Send a PING

            and wait for PONG

            If not PONG, raise error

        """

        _request = {}

        _request['type'] = messages.OSIM_RL.PING

        _request['payload'] = {}

        _response = self._blocking_request(_request)

        if _response['type'] != messages.OSIM_RL.PONG:

            raise Exception("Unable to perform handshake with the redis service. Expected PONG; received {}".format(json.dumps(_response)))

        else:

            return True

    def env_create(self):

        _request = {}

        _request['type'] = messages.OSIM_RL.ENV_CREATE

        _request['payload'] = {}

        _response = self._blocking_request(_request)

        observation = _response['payload']['observation']

        return observation

    def env_reset(self):

        _request = {}

        _request['type'] = messages.OSIM_RL.ENV_RESET

        _request['payload'] = {}

        _response = self._blocking_request(_request)

        observation = _response['payload']['observation']

        return observation

    def env_step(self, action, render=False):

        """

            Respond with [observation, reward, done, info]

        """

        action = np.array(action).tolist()

        _request = {}

        _request['type'] = messages.OSIM_RL.ENV_STEP

        _request['payload'] = {}

        _request['payload']['action'] = action

        _response = self._blocking_request(_request)

        _payload = _response['payload']

        observation = _payload['observation']

        reward = _payload['reward']

        done = _payload['done']

        info = _payload['info']

        return [observation, reward, done, info]

    def submit(self):

        _request = {}

        _request['type'] = messages.OSIM_RL.ENV_SUBMIT

        _request['payload'] = {}

        _response = self._blocking_request(_request)

        if os.getenv("CROWDAI_BLOCKING_SUBMIT"):

            """

            If the submission is supposed to happen as a blocking submit,

            then wait indefinitely for the evaluator to decide what to 

            do with the container.

            """

            while True:

                time.sleep(10)

        return _response['payload']