# coding=utf-8
# Copyright 2020 The Google Research Authors.
#
# 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.

# pylint: skip-file
"""Utility code for generating and saving image grids and checkpointing.

   The `save_image` code is copied from
   https://github.com/google/flax/blob/master/examples/vae/utils.py,
   which is a JAX equivalent to the same function in TorchVision
   (https://github.com/pytorch/vision/blob/master/torchvision/utils.py)
"""

import math
from typing import Any, Dict, Optional, TypeVar

import flax
import jax
import jax.numpy as jnp
import numpy as np
from PIL import Image
import blobfile

T = TypeVar("T")


def batch_add(a, b):
    return jax.vmap(lambda a, b: a + b)(a, b)


def batch_mul(a, b):
    return jax.vmap(lambda a, b: a * b)(a, b)


def load_training_state(filepath, state):
    with blobfile.open(filepath, "rb") as f:
        state = flax.serialization.from_bytes(state, f.read())
    return state


def save_image(ndarray, fp, nrow=8, padding=2, pad_value=0.0, format=None):
    """Make a grid of images and save it into an image file.

    Pixel values are assumed to be within [0, 1].

    Args:
      ndarray (array_like): 4D mini-batch images of shape (B x H x W x C).
      fp: A filename(string) or file object.
      nrow (int, optional): Number of images displayed in each row of the grid.
        The final grid size is ``(B / nrow, nrow)``. Default: ``8``.
      padding (int, optional): amount of padding. Default: ``2``.
      pad_value (float, optional): Value for the padded pixels. Default: ``0``.
      format(Optional):  If omitted, the format to use is determined from the
        filename extension. If a file object was used instead of a filename, this
        parameter should always be used.
    """
    if not (
        isinstance(ndarray, jnp.ndarray)
        or (
            isinstance(ndarray, list)
            and all(isinstance(t, jnp.ndarray) for t in ndarray)
        )
    ):
        raise TypeError("array_like of tensors expected, got {}".format(type(ndarray)))

    ndarray = jnp.asarray(ndarray)

    if ndarray.ndim == 4 and ndarray.shape[-1] == 1:  # single-channel images
        ndarray = jnp.concatenate((ndarray, ndarray, ndarray), -1)

    # make the mini-batch of images into a grid
    nmaps = ndarray.shape[0]
    xmaps = min(nrow, nmaps)
    ymaps = int(math.ceil(float(nmaps) / xmaps))
    height, width = int(ndarray.shape[1] + padding), int(ndarray.shape[2] + padding)
    num_channels = ndarray.shape[3]
    grid = jnp.full(
        (height * ymaps + padding, width * xmaps + padding, num_channels), pad_value
    ).astype(jnp.float32)
    k = 0
    for y in range(ymaps):
        for x in range(xmaps):
            if k >= nmaps:
                break
            grid = grid.at[
                y * height + padding : (y + 1) * height,
                x * width + padding : (x + 1) * width,
            ].set(ndarray[k])
            k = k + 1

    # Add 0.5 after unnormalizing to [0, 255] to round to nearest integer
    ndarr = np.asarray(jnp.clip(grid * 255.0 + 0.5, 0, 255).astype(jnp.uint8))
    im = Image.fromarray(ndarr.copy())
    im.save(fp, format=format)


def flatten_dict(config):
    """Flatten a hierarchical dict to a simple dict."""
    new_dict = {}
    for key, value in config.items():
        if isinstance(value, dict):
            sub_dict = flatten_dict(value)
            for subkey, subvalue in sub_dict.items():
                new_dict[key + "/" + subkey] = subvalue
        elif isinstance(value, tuple):
            new_dict[key] = str(value)
        else:
            new_dict[key] = value
    return new_dict