import os
import pathlib
import warnings
from copy import deepcopy

import gym
import numpy as np
import pytest
import torch as th

from stable_baselines3 import DDPG, DQN, HER, SAC, TD3
from stable_baselines3.common.bit_flipping_env import BitFlippingEnv
from stable_baselines3.common.vec_env import DummyVecEnv
from stable_baselines3.common.vec_env.obs_dict_wrapper import ObsDictWrapper
from stable_baselines3.her.goal_selection_strategy import GoalSelectionStrategy
from stable_baselines3.her.her import get_time_limit


@pytest.mark.parametrize("model_class", [SAC, TD3, DDPG, DQN])
@pytest.mark.parametrize("online_sampling", [True, False])
def test_her(model_class, online_sampling):
    """
    Test Hindsight Experience Replay.
    """
    n_bits = 4
    env = BitFlippingEnv(n_bits=n_bits, continuous=not (model_class == DQN))

    model = HER(
        "MlpPolicy",
        env,
        model_class,
        goal_selection_strategy="future",
        online_sampling=online_sampling,
        gradient_steps=1,
        train_freq=1,
        n_episodes_rollout=-1,
        max_episode_length=n_bits,
        policy_kwargs=dict(net_arch=[64]),
        learning_starts=100,
    )

    model.learn(total_timesteps=300)


@pytest.mark.parametrize(
    "goal_selection_strategy",
    [
        "final",
        "episode",
        "future",
        GoalSelectionStrategy.FINAL,
        GoalSelectionStrategy.EPISODE,
        GoalSelectionStrategy.FUTURE,
    ],
)
@pytest.mark.parametrize("online_sampling", [True, False])
def test_goal_selection_strategy(goal_selection_strategy, online_sampling):
    """
    Test different goal strategies.
    """
    env = BitFlippingEnv(continuous=True)

    model = HER(
        "MlpPolicy",
        env,
        SAC,
        goal_selection_strategy=goal_selection_strategy,
        online_sampling=online_sampling,
        gradient_steps=1,
        train_freq=1,
        n_episodes_rollout=-1,
        max_episode_length=10,
        policy_kwargs=dict(net_arch=[64]),
        learning_starts=100,
    )
    model.learn(total_timesteps=300)


@pytest.mark.parametrize("model_class", [SAC, TD3, DDPG, DQN])
@pytest.mark.parametrize("use_sde", [False, True])
@pytest.mark.parametrize("online_sampling", [False, True])
def test_save_load(tmp_path, model_class, use_sde, online_sampling):
    """
    Test if 'save' and 'load' saves and loads model correctly
    """
    if use_sde and model_class != SAC:
        pytest.skip("Only SAC has gSDE support")

    n_bits = 4
    env = BitFlippingEnv(n_bits=n_bits, continuous=not (model_class == DQN))

    kwargs = dict(use_sde=True) if use_sde else {}

    # create model
    model = HER(
        "MlpPolicy",
        env,
        model_class,
        n_sampled_goal=5,
        goal_selection_strategy="future",
        online_sampling=online_sampling,
        verbose=0,
        tau=0.05,
        batch_size=128,
        learning_rate=0.001,
        policy_kwargs=dict(net_arch=[64]),
        buffer_size=int(1e6),
        gamma=0.98,
        gradient_steps=1,
        train_freq=4,
        learning_starts=100,
        n_episodes_rollout=-1,
        max_episode_length=n_bits,
        **kwargs
    )

    model.learn(total_timesteps=300)

    env.reset()

    observations_list = []
    for _ in range(10):
        obs = env.step(env.action_space.sample())[0]
        observation = ObsDictWrapper.convert_dict(obs)
        observations_list.append(observation)
    observations = np.array(observations_list)

    # Get dictionary of current parameters
    params = deepcopy(model.policy.state_dict())

    # Modify all parameters to be random values
    random_params = dict((param_name, th.rand_like(param)) for param_name, param in params.items())

    # Update model parameters with the new random values
    model.policy.load_state_dict(random_params)

    new_params = model.policy.state_dict()
    # Check that all params are different now
    for k in params:
        assert not th.allclose(params[k], new_params[k]), "Parameters did not change as expected."

    params = new_params

    # get selected actions
    selected_actions, _ = model.predict(observations, deterministic=True)

    # Check
    model.save(tmp_path / "test_save.zip")
    del model
    model = HER.load(str(tmp_path / "test_save.zip"), env=env)

    # check if params are still the same after load
    new_params = model.policy.state_dict()

    # Check that all params are the same as before save load procedure now
    for key in params:
        assert th.allclose(params[key], new_params[key]), "Model parameters not the same after save and load."

    # check if model still selects the same actions
    new_selected_actions, _ = model.predict(observations, deterministic=True)
    assert np.allclose(selected_actions, new_selected_actions, 1e-4)

    # check if learn still works
    model.learn(total_timesteps=300)

    # Test that the change of parameters works
    model = HER.load(str(tmp_path / "test_save.zip"), env=env, verbose=3, learning_rate=2.0)
    assert model.model.learning_rate == 2.0
    assert model.verbose == 3

    # clear file from os
    os.remove(tmp_path / "test_save.zip")


@pytest.mark.parametrize("online_sampling, truncate_last_trajectory", [(False, None), (True, True), (True, False)])
def test_save_load_replay_buffer(tmp_path, recwarn, online_sampling, truncate_last_trajectory):
    """
    Test if 'save_replay_buffer' and 'load_replay_buffer' works correctly
    """
    # remove gym warnings
    warnings.filterwarnings(action="ignore", category=DeprecationWarning)
    warnings.filterwarnings(action="ignore", category=UserWarning, module="gym")

    path = pathlib.Path(tmp_path / "logs/replay_buffer.pkl")
    path.parent.mkdir(exist_ok=True, parents=True)  # to not raise a warning
    env = BitFlippingEnv(n_bits=4, continuous=True)
    model = HER(
        "MlpPolicy",
        env,
        SAC,
        goal_selection_strategy="future",
        online_sampling=online_sampling,
        gradient_steps=1,
        train_freq=1,
        n_episodes_rollout=-1,
        max_episode_length=4,
        buffer_size=int(2e4),
        policy_kwargs=dict(net_arch=[64]),
        seed=0,
    )
    model.learn(200)
    old_replay_buffer = deepcopy(model.replay_buffer)
    model.save_replay_buffer(path)
    del model.model.replay_buffer

    with pytest.raises(AttributeError):
        model.replay_buffer

    # Check that there is no warning
    assert len(recwarn) == 0

    model.load_replay_buffer(path, truncate_last_trajectory)

    if truncate_last_trajectory:
        assert len(recwarn) == 1
        warning = recwarn.pop(UserWarning)
        assert "The last trajectory in the replay buffer will be truncated" in str(warning.message)
    else:
        assert len(recwarn) == 0

    if online_sampling:
        n_episodes_stored = model.replay_buffer.n_episodes_stored
        assert np.allclose(
            old_replay_buffer.buffer["observation"][:n_episodes_stored],
            model.replay_buffer.buffer["observation"][:n_episodes_stored],
        )
        assert np.allclose(
            old_replay_buffer.buffer["next_obs"][:n_episodes_stored],
            model.replay_buffer.buffer["next_obs"][:n_episodes_stored],
        )
        assert np.allclose(
            old_replay_buffer.buffer["action"][:n_episodes_stored], model.replay_buffer.buffer["action"][:n_episodes_stored]
        )
        assert np.allclose(
            old_replay_buffer.buffer["reward"][:n_episodes_stored], model.replay_buffer.buffer["reward"][:n_episodes_stored]
        )
        # we might change the last done of the last trajectory so we don't compare it
        assert np.allclose(
            old_replay_buffer.buffer["done"][: n_episodes_stored - 1],
            model.replay_buffer.buffer["done"][: n_episodes_stored - 1],
        )
    else:
        assert np.allclose(old_replay_buffer.observations, model.replay_buffer.observations)
        assert np.allclose(old_replay_buffer.actions, model.replay_buffer.actions)
        assert np.allclose(old_replay_buffer.rewards, model.replay_buffer.rewards)
        assert np.allclose(old_replay_buffer.dones, model.replay_buffer.dones)

    # test if continuing training works properly
    reset_num_timesteps = False if truncate_last_trajectory is False else True
    model.learn(200, reset_num_timesteps=reset_num_timesteps)


def test_full_replay_buffer():
    """
    Test if HER works correctly with a full replay buffer when using online sampling.
    It should not sample the current episode which is not finished.
    """
    n_bits = 4
    env = BitFlippingEnv(n_bits=n_bits, continuous=True)

    # use small buffer size to get the buffer full
    model = HER(
        "MlpPolicy",
        env,
        SAC,
        goal_selection_strategy="future",
        online_sampling=True,
        gradient_steps=1,
        train_freq=1,
        n_episodes_rollout=-1,
        max_episode_length=n_bits,
        policy_kwargs=dict(net_arch=[64]),
        learning_starts=1,
        buffer_size=20,
        verbose=1,
    )

    model.learn(total_timesteps=100)


def test_get_max_episode_length():
    dict_env = DummyVecEnv([lambda: BitFlippingEnv()])

    # Cannot infer max epsiode length
    with pytest.raises(ValueError):
        get_time_limit(dict_env, current_max_episode_length=None)

    default_length = 10
    assert get_time_limit(dict_env, current_max_episode_length=default_length) == default_length

    env = gym.make("CartPole-v1")
    vec_env = DummyVecEnv([lambda: env])

    assert get_time_limit(vec_env, current_max_episode_length=None) == 500
    # Overwrite max_episode_steps
    assert get_time_limit(vec_env, current_max_episode_length=default_length) == default_length

    # Set max_episode_steps to None
    env.spec.max_episode_steps = None
    vec_env = DummyVecEnv([lambda: env])
    with pytest.raises(ValueError):
        get_time_limit(vec_env, current_max_episode_length=None)

    # Initialize HER and specify max_episode_length, should not raise an issue
    HER("MlpPolicy", dict_env, DQN, max_episode_length=5)

    with pytest.raises(ValueError):
        HER("MlpPolicy", dict_env, DQN)

    # Wrapped in a timelimit, should be fine
    # Note: it requires env.spec to be defined
    env = DummyVecEnv([lambda: gym.wrappers.TimeLimit(BitFlippingEnv(), 10)])
    HER("MlpPolicy", env, DQN)


@pytest.mark.parametrize("online_sampling", [False, True])
@pytest.mark.parametrize("n_bits", [10])
def test_performance_her(online_sampling, n_bits):
    """
    That DQN+HER can solve BitFlippingEnv.
    It should not work when n_sampled_goal=0 (DQN alone).
    """
    env = BitFlippingEnv(n_bits=n_bits, continuous=False)

    model = HER(
        "MlpPolicy",
        env,
        DQN,
        n_sampled_goal=5,
        goal_selection_strategy="future",
        online_sampling=online_sampling,
        verbose=1,
        learning_rate=5e-4,
        max_episode_length=n_bits,
        train_freq=1,
        learning_starts=100,
        exploration_final_eps=0.02,
        target_update_interval=500,
        seed=0,
        batch_size=32,
    )

    model.learn(total_timesteps=5000, log_interval=50)

    # 90% training success
    assert np.mean(model.ep_success_buffer) > 0.90