# Copyright (c) 2024-2025, The Isaac Lab Project Developers.
# All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause

"""Script to replay demonstrations with Isaac Lab environments."""

"""Launch Isaac Sim Simulator first."""

import argparse

from isaaclab.app import AppLauncher

# add argparse arguments
parser = argparse.ArgumentParser(description="Replay demonstrations in Isaac Lab environments.")
parser.add_argument("--num_envs", type=int, default=1, help="Number of environments to replay episodes.")
parser.add_argument("--task", type=str, default=None, help="Force to use the specified task.")
parser.add_argument(
    "--select_episodes",
    type=int,
    nargs="+",
    default=[],
    help="A list of episode indices to be replayed. Keep empty to replay all in the dataset file.",
)
parser.add_argument("--dataset_file", type=str, default="datasets/dataset.hdf5", help="Dataset file to be replayed.")
parser.add_argument(
    "--validate_states",
    action="store_true",
    default=False,
    help=(
        "Validate if the states, if available, match between loaded from datasets and replayed. Only valid if"
        " --num_envs is 1."
    ),
)

# append AppLauncher cli args
AppLauncher.add_app_launcher_args(parser)
# parse the arguments
args_cli = parser.parse_args()
# args_cli.headless = True

# launch the simulator
app_launcher = AppLauncher(args_cli)
simulation_app = app_launcher.app

"""Rest everything follows."""

import contextlib
import gymnasium as gym
import os
import torch

from isaaclab.devices import Se3Keyboard
from isaaclab.utils.datasets import EpisodeData, HDF5DatasetFileHandler

import isaaclab_tasks  # noqa: F401
from isaaclab_tasks.utils.parse_cfg import parse_env_cfg

is_paused = False


def play_cb():
    global is_paused
    is_paused = False


def pause_cb():
    global is_paused
    is_paused = True


def compare_states(state_from_dataset, runtime_state, runtime_env_index) -> (bool, str):
    """Compare states from dataset and runtime.

    Args:
        state_from_dataset: State from dataset.
        runtime_state: State from runtime.
        runtime_env_index: Index of the environment in the runtime states to be compared.

    Returns:
        bool: True if states match, False otherwise.
        str: Log message if states don't match.
    """
    states_matched = True
    output_log = ""
    for asset_type in ["articulation", "rigid_object"]:
        for asset_name in runtime_state[asset_type].keys():
            for state_name in runtime_state[asset_type][asset_name].keys():
                runtime_asset_state = runtime_state[asset_type][asset_name][state_name][runtime_env_index]
                dataset_asset_state = state_from_dataset[asset_type][asset_name][state_name]
                if len(dataset_asset_state) != len(runtime_asset_state):
                    raise ValueError(f"State shape of {state_name} for asset {asset_name} don't match")
                for i in range(len(dataset_asset_state)):
                    if abs(dataset_asset_state[i] - runtime_asset_state[i]) > 0.01:
                        states_matched = False
                        output_log += f'\tState ["{asset_type}"]["{asset_name}"]["{state_name}"][{i}] don\'t match\r\n'
                        output_log += f"\t  Dataset:\t{dataset_asset_state[i]}\r\n"
                        output_log += f"\t  Runtime: \t{runtime_asset_state[i]}\r\n"
    return states_matched, output_log


def main():
    """Replay episodes loaded from a file."""
    global is_paused

    # Load dataset
    if not os.path.exists(args_cli.dataset_file):
        raise FileNotFoundError(f"The dataset file {args_cli.dataset_file} does not exist.")
    dataset_file_handler = HDF5DatasetFileHandler()
    dataset_file_handler.open(args_cli.dataset_file)
    env_name = dataset_file_handler.get_env_name()
    episode_count = dataset_file_handler.get_num_episodes()

    if episode_count == 0:
        print("No episodes found in the dataset.")
        exit()

    episode_indices_to_replay = args_cli.select_episodes
    if len(episode_indices_to_replay) == 0:
        episode_indices_to_replay = list(range(episode_count))

    if args_cli.task is not None:
        env_name = args_cli.task
    if env_name is None:
        raise ValueError("Task/env name was not specified nor found in the dataset.")

    num_envs = args_cli.num_envs

    env_cfg = parse_env_cfg(env_name, device=args_cli.device, num_envs=num_envs)

    # Disable all recorders and terminations
    env_cfg.recorders = {}
    env_cfg.terminations = {}

    # create environment from loaded config
    env = gym.make(env_name, cfg=env_cfg).unwrapped

    teleop_interface = Se3Keyboard(pos_sensitivity=0.1, rot_sensitivity=0.1)
    teleop_interface.add_callback("N", play_cb)
    teleop_interface.add_callback("B", pause_cb)
    print('Press "B" to pause and "N" to resume the replayed actions.')

    # Determine if state validation should be conducted
    state_validation_enabled = False
    if args_cli.validate_states and num_envs == 1:
        state_validation_enabled = True
    elif args_cli.validate_states and num_envs > 1:
        print("Warning: State validation is only supported with a single environment. Skipping state validation.")

    # reset before starting
    env.reset()
    teleop_interface.reset()

    # simulate environment -- run everything in inference mode
    episode_names = list(dataset_file_handler.get_episode_names())
    replayed_episode_count = 0
    with contextlib.suppress(KeyboardInterrupt) and torch.inference_mode():
        while simulation_app.is_running() and not simulation_app.is_exiting():
            env_episode_data_map = {index: EpisodeData() for index in range(num_envs)}
            first_loop = True
            has_next_action = True
            while has_next_action:
                # initialize actions with zeros so those without next action will not move
                actions = torch.zeros(env.action_space.shape)
                has_next_action = False
                for env_id in range(num_envs):
                    env_next_action = env_episode_data_map[env_id].get_next_action()
                    if env_next_action is None:
                        next_episode_index = None
                        while episode_indices_to_replay:
                            next_episode_index = episode_indices_to_replay.pop(0)
                            if next_episode_index < episode_count:
                                break
                            next_episode_index = None

                        if next_episode_index is not None:
                            replayed_episode_count += 1
                            print(f"{replayed_episode_count :4}: Loading #{next_episode_index} episode to env_{env_id}")
                            episode_data = dataset_file_handler.load_episode(
                                episode_names[next_episode_index], env.device
                            )
                            env_episode_data_map[env_id] = episode_data
                            # Set initial state for the new episode
                            initial_state = episode_data.get_initial_state()
                            env.reset_to(initial_state, torch.tensor([env_id], device=env.device), is_relative=True)
                            # Get the first action for the new episode
                            env_next_action = env_episode_data_map[env_id].get_next_action()
                            has_next_action = True
                        else:
                            continue
                    else:
                        has_next_action = True
                    actions[env_id] = env_next_action
                if first_loop:
                    first_loop = False
                else:
                    while is_paused:
                        env.sim.render()
                        continue
                env.step(actions)

                if state_validation_enabled:
                    state_from_dataset = env_episode_data_map[0].get_next_state()
                    if state_from_dataset is not None:
                        print(
                            f"Validating states at action-index: {env_episode_data_map[0].next_state_index - 1 :4}",
                            end="",
                        )
                        current_runtime_state = env.scene.get_state(is_relative=True)
                        states_matched, comparison_log = compare_states(state_from_dataset, current_runtime_state, 0)
                        if states_matched:
                            print("\t- matched.")
                        else:
                            print("\t- mismatched.")
                            print(comparison_log)
            break
    # Close environment after replay in complete
    plural_trailing_s = "s" if replayed_episode_count > 1 else ""
    print(f"Finished replaying {replayed_episode_count} episode{plural_trailing_s}.")
    env.close()


if __name__ == "__main__":
    # run the main function
    main()
    # close sim app
    simulation_app.close()
