#!/usr/bin/env python

# Copyright 2024 The HuggingFace Inc. team. All rights reserved.
#
# Licensed 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 io
import logging
import pickle
import queue
from statistics import mean, quantiles
import signal
from functools import lru_cache

# from lerobot.scripts.eval import eval_policy
from threading import Thread

import grpc
import hydra
import torch
from omegaconf import DictConfig
from torch import nn

# TODO: Remove the import of maniskill
# from lerobot.common.envs.factory import make_maniskill_env
# from lerobot.common.envs.utils import preprocess_maniskill_observation
from lerobot.common.policies.factory import make_policy
from lerobot.common.policies.sac.modeling_sac import SACPolicy
from lerobot.common.robot_devices.robots.factory import make_robot
from lerobot.common.robot_devices.robots.utils import Robot
from lerobot.common.utils.utils import (
    TimerManager,
    get_safe_torch_device,
    set_global_seed,
)
from lerobot.scripts.server import hilserl_pb2, hilserl_pb2_grpc
from lerobot.scripts.server.buffer import (
    Transition,
    move_state_dict_to_device,
    move_transition_to_device,
    bytes_buffer_size,
)
from lerobot.scripts.server.gym_manipulator import get_classifier, make_robot_env
from lerobot.scripts.server import learner_service

from threading import Event

logging.basicConfig(level=logging.INFO)

parameters_queue = queue.Queue(maxsize=1)
message_queue = queue.Queue(maxsize=1_000_000)

ACTOR_SHUTDOWN_TIMEOUT = 30


class ActorInformation:
    """
    This helper class is used to differentiate between two types of messages that are placed in the same queue during streaming:

    - **Transition Data:** Contains experience tuples (observation, action, reward, next observation) collected during interaction.
    - **Interaction Messages:** Encapsulates statistics related to the interaction process.

    Attributes:
        transition (Optional): Transition data to be sent to the learner.
        interaction_message (Optional): Iteraction message providing additional statistics for logging.
    """

    def __init__(self, transition=None, interaction_message=None):
        self.transition = transition
        self.interaction_message = interaction_message


def receive_policy(
    learner_client: hilserl_pb2_grpc.LearnerServiceStub,
    shutdown_event: Event,
    parameters_queue: queue.Queue,
):
    logging.info("[ACTOR] Start receiving parameters from the Learner")
    bytes_buffer = io.BytesIO()
    step = 0
    try:
        for model_update in learner_client.StreamParameters(hilserl_pb2.Empty()):
            if shutdown_event.is_set():
                logging.info("[ACTOR] Shutting down policy streaming receiver")
                return hilserl_pb2.Empty()

            if model_update.transfer_state == hilserl_pb2.TransferState.TRANSFER_BEGIN:
                bytes_buffer.seek(0)
                bytes_buffer.truncate(0)
                bytes_buffer.write(model_update.parameter_bytes)
                logging.info("Received model update at step 0")
                step = 0
                continue
            elif (
                model_update.transfer_state == hilserl_pb2.TransferState.TRANSFER_MIDDLE
            ):
                bytes_buffer.write(model_update.parameter_bytes)
                step += 1
                logging.info(f"Received model update at step {step}")
            elif model_update.transfer_state == hilserl_pb2.TransferState.TRANSFER_END:
                bytes_buffer.write(model_update.parameter_bytes)
                logging.info(
                    f"Received model update at step end size {bytes_buffer_size(bytes_buffer)}"
                )

                state_dict = torch.load(bytes_buffer)

                bytes_buffer.seek(0)
                bytes_buffer.truncate(0)
                step = 0

                logging.info("Model updated")

                parameters_queue.put(state_dict)

    except grpc.RpcError as e:
        logging.error(f"[ACTOR] gRPC error: {e}")

    return hilserl_pb2.Empty()


def transitions_stream(shutdown_event: Event, message_queue: queue.Queue):
    while not shutdown_event.is_set():
        try:
            message = message_queue.get(block=True, timeout=5)
        except queue.Empty:
            logging.debug("[ACTOR] Transition queue is empty")
            continue

        if message.transition is not None:
            transition_to_send_to_learner: list[Transition] = [
                move_transition_to_device(transition=T, device="cpu")
                for T in message.transition
            ]
            # Check for NaNs in transitions before sending to learner
            for transition in transition_to_send_to_learner:
                for key, value in transition["state"].items():
                    if torch.isnan(value).any():
                        logging.warning(f"Found NaN values in transition {key}")
            buf = io.BytesIO()
            torch.save(transition_to_send_to_learner, buf)
            transition_bytes = buf.getvalue()

            transition_message = hilserl_pb2.Transition(
                transition_bytes=transition_bytes
            )

            response = hilserl_pb2.ActorInformation(transition=transition_message)

        elif message.interaction_message is not None:
            content = hilserl_pb2.InteractionMessage(
                interaction_message_bytes=pickle.dumps(message.interaction_message)
            )
            response = hilserl_pb2.ActorInformation(interaction_message=content)

        yield response

    return hilserl_pb2.Empty()


def send_transitions(
    learner_client: hilserl_pb2_grpc.LearnerServiceStub,
    shutdown_event: Event,
    message_queue: queue.Queue,
):
    """
    Streams data from the actor to the learner.

    This function continuously retrieves messages from the queue and processes them based on their type:

    - **Transition Data:**
        - A batch of transitions (observation, action, reward, next observation) is collected.
        - Transitions are moved to the CPU and serialized using PyTorch.
        - The serialized data is wrapped in a `hilserl_pb2.Transition` message and sent to the learner.

    - **Interaction Messages:**
        - Contains useful statistics about episodic rewards and policy timings.
        - The message is serialized using `pickle` and sent to the learner.

    Yields:
        hilserl_pb2.ActorInformation: The response message containing either transition data or an interaction message.
    """
    try:
        learner_client.ReceiveTransitions(
            transitions_stream(shutdown_event, message_queue)
        )
    except grpc.RpcError as e:
        logging.error(f"[ACTOR] gRPC error: {e}")

    logging.info("[ACTOR] Finished streaming transitions")


@lru_cache(maxsize=1)
def learner_service_client(
    host="127.0.0.1", port=50051
) -> tuple[hilserl_pb2_grpc.LearnerServiceStub, grpc.Channel]:
    import json

    """
    Returns a client for the learner service.

    GRPC uses HTTP/2, which is a binary protocol and multiplexes requests over a single connection.
    So we need to create only one client and reuse it.
    """

    service_config = {
        "methodConfig": [
            {
                "name": [{}],  # Applies to ALL methods in ALL services
                "retryPolicy": {
                    "maxAttempts": 7,  # Max retries (total attempts = 5)
                    "initialBackoff": "0.1s",  # First retry after 0.1s
                    "maxBackoff": "2s",  # Max wait time between retries
                    "backoffMultiplier": 2,  # Exponential backoff factor
                    "retryableStatusCodes": [
                        "UNAVAILABLE",
                        "DEADLINE_EXCEEDED",
                    ],  # Retries on network failures
                },
            }
        ]
    }

    service_config_json = json.dumps(service_config)

    channel = grpc.insecure_channel(
        f"{host}:{port}",
        options=[
            ("grpc.max_receive_message_length", learner_service.MAX_MESSAGE_SIZE),
            ("grpc.max_send_message_length", learner_service.MAX_MESSAGE_SIZE),
            ("grpc.enable_retries", 1),
            ("grpc.service_config", service_config_json),
        ],
    )
    stub = hilserl_pb2_grpc.LearnerServiceStub(channel)
    logging.info("[LEARNER] Learner service client created")
    return stub, channel


def update_policy_parameters(policy: SACPolicy, parameters_queue: queue.Queue, device):
    if not parameters_queue.empty():
        logging.info("[ACTOR] Load new parameters from Learner.")
        state_dict = parameters_queue.get()
        state_dict = move_state_dict_to_device(state_dict, device=device)
        policy.load_state_dict(state_dict)


def act_with_policy(
    cfg: DictConfig, robot: Robot, reward_classifier: nn.Module, shutdown_event: Event
):
    """
    Executes policy interaction within the environment.

    This function rolls out the policy in the environment, collecting interaction data and pushing it to a queue for streaming to the learner.
    Once an episode is completed, updated network parameters received from the learner are retrieved from a queue and loaded into the network.

    Args:
        cfg (DictConfig): Configuration settings for the interaction process.
    """

    logging.info("make_env online")

    online_env = make_robot_env(
        robot=robot, reward_classifier=reward_classifier, cfg=cfg
    )

    set_global_seed(cfg.seed)
    device = get_safe_torch_device(cfg.device, log=True)

    torch.backends.cudnn.benchmark = True
    torch.backends.cuda.matmul.allow_tf32 = True

    logging.info("make_policy")

    # HACK: This is an ugly hack to pass the normalization parameters to the policy
    # Because the action space is dynamic so we override the output normalization parameters
    # it's ugly, we know ... and we will fix it
    min_action_space: list = online_env.action_space.spaces[0].low.tolist()
    max_action_space: list = online_env.action_space.spaces[0].high.tolist()
    output_normalization_params: dict[dict[str, list]] = {
        "action": {"min": min_action_space, "max": max_action_space}
    }
    cfg.policy.output_normalization_params = output_normalization_params
    cfg.policy.output_shapes["action"] = online_env.action_space.spaces[0].shape

    ### Instantiate the policy in both the actor and learner processes
    ### To avoid sending a SACPolicy object through the port, we create a policy intance
    ### on both sides, the learner sends the updated parameters every n steps to update the actor's parameters
    # TODO: At some point we should just need make sac policy
    policy: SACPolicy = make_policy(
        hydra_cfg=cfg,
        # dataset_stats=offline_dataset.meta.stats if not cfg.resume else None,
        # Hack: But if we do online training, we do not need dataset_stats
        dataset_stats=None,
        # TODO: Handle resume training
        device=device,
    )
    policy = torch.compile(policy)
    assert isinstance(policy, nn.Module)

    obs, info = online_env.reset()

    # NOTE: For the moment we will solely handle the case of a single environment
    sum_reward_episode = 0
    list_transition_to_send_to_learner = []
    list_policy_time = []
    episode_intervention = False

    for interaction_step in range(cfg.training.online_steps):
        if shutdown_event.is_set():
            logging.info("[ACTOR] Shutdown signal received. Exiting...")
            return

        if interaction_step >= cfg.training.online_step_before_learning:
            # Time policy inference and check if it meets FPS requirement
            with TimerManager(
                elapsed_time_list=list_policy_time,
                label="Policy inference time",
                log=False,
            ) as timer:  # noqa: F841
                action = policy.select_action(batch=obs)
            policy_fps = 1.0 / (list_policy_time[-1] + 1e-9)

            log_policy_frequency_issue(
                policy_fps=policy_fps, cfg=cfg, interaction_step=interaction_step
            )

            next_obs, reward, done, truncated, info = online_env.step(
                action.squeeze(dim=0).cpu().numpy()
            )
        else:
            # TODO (azouitine): Make a custom space for torch tensor
            action = online_env.action_space.sample()
            next_obs, reward, done, truncated, info = online_env.step(action)

            # HACK: We have only one env but we want to batch it, it will be resolved with the torch box
            action = (
                torch.from_numpy(action[0])
                .to(device, non_blocking=device.type == "cuda")
                .unsqueeze(dim=0)
            )

        sum_reward_episode += float(reward)

        # NOTE: We overide the action if the intervention is True, because the action applied is the intervention action
        if "is_intervention" in info and info["is_intervention"]:
            # TODO: Check the shape
            # NOTE: The action space for demonstration before hand is with the full action space
            # but sometimes for example we want to deactivate the gripper
            action = info["action_intervention"]
            episode_intervention = True

        # Check for NaN values in observations
        for key, tensor in obs.items():
            if torch.isnan(tensor).any():
                logging.error(
                    f"[ACTOR] NaN values found in obs[{key}] at step {interaction_step}"
                )

        list_transition_to_send_to_learner.append(
            Transition(
                state=obs,
                action=action,
                reward=reward,
                next_state=next_obs,
                done=done,
                truncated=truncated,  # TODO: (azouitine) Handle truncation properly
                complementary_info=info,  # TODO Handle information for the transition, is_demonstraction: bool
            )
        )

        # assign obs to the next obs and continue the rollout
        obs = next_obs

        # HACK: We have only one env but we want to batch it, it will be resolved with the torch box
        # Because we are using a single environment we can index at zero
        if done or truncated:
            # TODO: Handle logging for episode information
            logging.info(
                f"[ACTOR] Global step {interaction_step}: Episode reward: {sum_reward_episode}"
            )

            update_policy_parameters(
                policy=policy.actor, parameters_queue=parameters_queue, device=device
            )

            if len(list_transition_to_send_to_learner) > 0:
                send_transitions_in_chunks(
                    transitions=list_transition_to_send_to_learner,
                    message_queue=message_queue,
                    chunk_size=4,
                )
                list_transition_to_send_to_learner = []

            stats = get_frequency_stats(list_policy_time)
            list_policy_time.clear()

            # Send episodic reward to the learner
            message_queue.put(
                ActorInformation(
                    interaction_message={
                        "Episodic reward": sum_reward_episode,
                        "Interaction step": interaction_step,
                        "Episode intervention": int(episode_intervention),
                        **stats,
                    }
                )
            )
            sum_reward_episode = 0.0
            episode_intervention = False
            obs, info = online_env.reset()


def send_transitions_in_chunks(transitions: list, message_queue, chunk_size: int = 100):
    """Send transitions to learner in smaller chunks to avoid network issues.

    Args:
        transitions: List of transitions to send
        message_queue: Queue to send messages to learner
        chunk_size: Size of each chunk to send
    """
    for i in range(0, len(transitions), chunk_size):
        chunk = transitions[i : i + chunk_size]
        logging.debug(f"[ACTOR] Sending chunk of {len(chunk)} transitions to Learner.")
        message_queue.put(ActorInformation(transition=chunk))


def get_frequency_stats(list_policy_time: list[float]) -> dict[str, float]:
    stats = {}
    list_policy_fps = [1.0 / t for t in list_policy_time]
    if len(list_policy_fps) > 1:
        policy_fps = mean(list_policy_fps)
        quantiles_90 = quantiles(list_policy_fps, n=10)[-1]
        logging.debug(f"[ACTOR] Average policy frame rate: {policy_fps}")
        logging.debug(f"[ACTOR] Policy frame rate 90th percentile: {quantiles_90}")
        stats = {
            "Policy frequency [Hz]": policy_fps,
            "Policy frequency 90th-p [Hz]": quantiles_90,
        }
    return stats


def log_policy_frequency_issue(
    policy_fps: float, cfg: DictConfig, interaction_step: int
):
    if policy_fps < cfg.fps:
        logging.warning(
            f"[ACTOR] Policy FPS {policy_fps:.1f} below required {cfg.fps} at step {interaction_step}"
        )


@hydra.main(version_base="1.2", config_name="default", config_path="../../configs")
def actor_cli(cfg: dict):
    robot = make_robot(cfg=cfg.robot)

    shutdown_event = Event()

    # Define signal handler
    def signal_handler(signum, frame):
        logging.info("Shutdown signal received. Cleaning up...")
        shutdown_event.set()

    signal.signal(signal.SIGINT, signal_handler)  # Ctrl+C
    signal.signal(signal.SIGTERM, signal_handler)  # Termination request (kill)
    signal.signal(signal.SIGHUP, signal_handler)  # Terminal closed/Hangup
    signal.signal(signal.SIGQUIT, signal_handler)  # Ctrl+\

    learner_client, grpc_channel = learner_service_client(
        host=cfg.actor_learner_config.learner_host,
        port=cfg.actor_learner_config.learner_port,
    )

    receive_policy_thread = Thread(
        target=receive_policy,
        args=(learner_client, shutdown_event, parameters_queue),
        daemon=True,
    )

    transitions_thread = Thread(
        target=send_transitions,
        args=(learner_client, shutdown_event, message_queue),
        daemon=True,
    )

    # HACK: FOR MANISKILL we do not have a reward classifier
    # TODO: Remove this once we merge into main
    reward_classifier = None
    if (
        cfg.env.reward_classifier.pretrained_path is not None
        and cfg.env.reward_classifier.config_path is not None
    ):
        reward_classifier = get_classifier(
            pretrained_path=cfg.env.reward_classifier.pretrained_path,
            config_path=cfg.env.reward_classifier.config_path,
        )

    policy_thread = Thread(
        target=act_with_policy,
        daemon=True,
        args=(cfg, robot, reward_classifier, shutdown_event),
    )

    transitions_thread.start()
    policy_thread.start()
    receive_policy_thread.start()

    shutdown_event.wait()
    logging.info("[ACTOR] Shutdown event received")
    grpc_channel.close()

    policy_thread.join()
    logging.info("[ACTOR] Policy thread joined")
    transitions_thread.join()
    logging.info("[ACTOR] Transitions thread joined")
    receive_policy_thread.join()
    logging.info("[ACTOR] Receive policy thread joined")


if __name__ == "__main__":
    actor_cli()