"""Tests for the pixel observation wrapper."""
from typing import Optional

import pytest
import numpy as np

import gym
from gym import spaces
from gym.wrappers.pixel_observation import PixelObservationWrapper, STATE_KEY


class FakeEnvironment(gym.Env):
    def __init__(self):
        self.action_space = spaces.Box(shape=(1,), low=-1, high=1, dtype=np.float32)

    def render(self, width=32, height=32, *args, **kwargs):
        del args
        del kwargs
        image_shape = (height, width, 3)
        return np.zeros(image_shape, dtype=np.uint8)

    def reset(self, seed: Optional[int] = None):
        super().reset(seed=seed)
        observation = self.observation_space.sample()
        return observation

    def step(self, action):
        del action
        observation = self.observation_space.sample()
        reward, terminal, info = 0.0, False, {}
        return observation, reward, terminal, info


class FakeArrayObservationEnvironment(FakeEnvironment):
    def __init__(self, *args, **kwargs):
        self.observation_space = spaces.Box(
            shape=(2,), low=-1, high=1, dtype=np.float32
        )
        super(FakeArrayObservationEnvironment, self).__init__(*args, **kwargs)


class FakeDictObservationEnvironment(FakeEnvironment):
    def __init__(self, *args, **kwargs):
        self.observation_space = spaces.Dict(
            {
                "state": spaces.Box(shape=(2,), low=-1, high=1, dtype=np.float32),
            }
        )
        super(FakeDictObservationEnvironment, self).__init__(*args, **kwargs)


class TestPixelObservationWrapper(object):
    @pytest.mark.parametrize("pixels_only", (True, False))
    def test_dict_observation(self, pixels_only):
        pixel_key = "rgb"

        env = FakeDictObservationEnvironment()

        # Make sure we are testing the right environment for the test.
        observation_space = env.observation_space
        assert isinstance(observation_space, spaces.Dict)

        width, height = (320, 240)

        # The wrapper should only add one observation.
        wrapped_env = PixelObservationWrapper(
            env,
            pixel_keys=(pixel_key,),
            pixels_only=pixels_only,
            render_kwargs={pixel_key: {"width": width, "height": height}},
        )

        assert isinstance(wrapped_env.observation_space, spaces.Dict)

        if pixels_only:
            assert len(wrapped_env.observation_space.spaces) == 1
            assert list(wrapped_env.observation_space.spaces.keys()) == [pixel_key]
        else:
            assert (
                len(wrapped_env.observation_space.spaces)
                == len(observation_space.spaces) + 1
            )
            expected_keys = list(observation_space.spaces.keys()) + [pixel_key]
            assert list(wrapped_env.observation_space.spaces.keys()) == expected_keys

        # Check that the added space item is consistent with the added observation.
        observation = wrapped_env.reset()
        rgb_observation = observation[pixel_key]

        assert rgb_observation.shape == (height, width, 3)
        assert rgb_observation.dtype == np.uint8

    @pytest.mark.parametrize("pixels_only", (True, False))
    def test_single_array_observation(self, pixels_only):
        pixel_key = "depth"

        env = FakeArrayObservationEnvironment()
        observation_space = env.observation_space
        assert isinstance(observation_space, spaces.Box)

        wrapped_env = PixelObservationWrapper(
            env, pixel_keys=(pixel_key,), pixels_only=pixels_only
        )
        wrapped_env.observation_space = wrapped_env.observation_space
        assert isinstance(wrapped_env.observation_space, spaces.Dict)

        if pixels_only:
            assert len(wrapped_env.observation_space.spaces) == 1
            assert list(wrapped_env.observation_space.spaces.keys()) == [pixel_key]
        else:
            assert len(wrapped_env.observation_space.spaces) == 2
            assert list(wrapped_env.observation_space.spaces.keys()) == [
                STATE_KEY,
                pixel_key,
            ]

        observation = wrapped_env.reset()
        depth_observation = observation[pixel_key]

        assert depth_observation.shape == (32, 32, 3)
        assert depth_observation.dtype == np.uint8

        if not pixels_only:
            assert isinstance(observation[STATE_KEY], np.ndarray)

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