<filename>mava/utils/environments/meltingpot_utils.py
# python3
# Copyright 2021 InstaDeep Ltd. 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.

from typing import Any, Union

try:
    from meltingpot.python import scenario, substrate  # type: ignore
    from meltingpot.python.scenario import AVAILABLE_SCENARIOS, Scenario  # type: ignore
    from meltingpot.python.substrate import (  # type: ignore
        AVAILABLE_SUBSTRATES,
        Substrate,
    )
    from ml_collections import config_dict  # type: ignore

    from mava.wrappers.meltingpot import MeltingpotEnvWrapper
except ModuleNotFoundError:
    Scenario = Any
    Substrate = Any


class EnvironmentFactory:
    def __init__(self, substrate: str = None, scenario: str = None):
        """Initializes the env factory object

        sets the substrate/scenario using the available ones in meltingpot

        Args:
            substrate (str, optional): what substrate to use. Defaults to None.
            scenario (str, optional): what scenario to use. Defaults to None.
        """
        assert (substrate is None) or (
            scenario is None
        ), "substrate or scenario must be specified"
        assert not (
            substrate is not None and scenario is not None
        ), "Cannot specify both substrate and scenario"

        if substrate is not None:
            substrates = [*AVAILABLE_SUBSTRATES]
            assert (
                substrate in substrates
            ), f"substrate cannot be f{substrate}, use any of {substrates}"
            self._substrate_name = substrate
            self._env_fn = self._substrate

        elif scenario is not None:
            scenarios = [*[k for k in AVAILABLE_SCENARIOS]]
            assert (
                scenario in scenarios
            ), f"substrate cannot be f{substrate}, use any of {scenarios}"
            self._scenario_name = scenario
            self._env_fn = self._scenario

    def _substrate(self) -> Substrate:
        """Returns a substrate as an environment

        Returns:
            [Substrate]: A substrate
        """
        env = load_substrate(self._substrate_name)
        return MeltingpotEnvWrapper(env)

    def _scenario(self) -> Scenario:
        """Returns a scenario as an environment

        Returns:
            [Scenario]: A scenario or None
        """

        env = load_scenario(self._scenario_name)
        return MeltingpotEnvWrapper(env)

    def __call__(self, evaluation: bool = False) -> Union[Substrate, Scenario]:
        """Creates an environment

        Returns:
            (Union[Substrate, Scenario]): The created environment
        """
        env = self._env_fn()  # type: ignore
        return env


def load_substrate(substrate_name: str) -> Substrate:
    """Loads a substrate from the available substrates

    Args:
        substrate_name (str): substrate name

    Returns:
        Substrate: A multi-agent environment
    """
    config = substrate.get_config(substrate_name)
    env_config = config_dict.ConfigDict(config)

    return substrate.build(env_config)


def load_scenario(scenario_name: str) -> Scenario:
    """Loads a substrate from the available substrates

    Args:
        scenerio_name (str): scenario name

    Returns:
        Scenario: A multi-agent environment with background bots
    """
    config = scenario.get_config(scenario_name)
    env_config = config_dict.ConfigDict(config)

    return scenario.build(env_config)
