# Copyright 2022 The Plenoptix 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,
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""" Helper functions for visualizing outputs """

from typing import Optional

import torch
from matplotlib import cm
from torchtyping import TensorType


def apply_colormap(image: TensorType[..., 1], cmap="viridis") -> TensorType[..., 3]:
    """Convert single channel to a color image.

    Args:
        image (TensorType[..., 1]): Single channel image.
        cmap (str, optional): Colormap for image. Defaults to 'turbo'.

    Returns:
        TensorType[..., 3]: Colored image
    """

    colormap = cm.get_cmap(cmap)
    colormap = torch.tensor(colormap.colors).to(image.device)
    image_long = (image * 255).long()
    image_long_min = torch.min(image_long)
    image_long_max = torch.max(image_long)
    assert image_long_min >= 0, f"the min value is {image_long_min}"
    assert image_long_max <= 255, f"the max value is {image_long_max}"
    return colormap[image_long[..., 0]]


def apply_depth_colormap(
    depth: TensorType[..., 1],
    accumulation: Optional[TensorType[..., 1]] = None,
    near_plane: Optional[float] = None,
    far_plane: Optional[float] = None,
    cmap="turbo",
) -> TensorType[..., 3]:
    """Converts a depth image to color for easier analysis.

    Args:
        depth (TensorType[..., 1]): Depth image.
        accumulation (TensorType[..., 1], optional): Ray accumulation used for masking vis. Defaults to None.
        near_plane (float, optional): Closest depth to consider. If None, use min image value. Defaults to None.
        far_plane (float, optional): Furthest depth to consider. If None, use max image value. Defaults to None.
        cmap (str, optional): Colormap to apply. Defaults to "turbo".

    Returns:
        TensorType[..., 3]: Colored depth image
    """

    near_plane = near_plane or torch.min(depth)
    far_plane = far_plane or torch.max(depth)

    depth = (depth - near_plane) / (far_plane - near_plane + 1e-10)
    depth = torch.clip(depth, 0, 1)
    # depth = torch.nan_to_num(depth, nan=0.0) # TODO(ethan): remove this

    colored_image = apply_colormap(depth, cmap=cmap)

    if accumulation is not None:
        colored_image = colored_image * accumulation + (1 - accumulation)

    return colored_image