# coding=utf-8
# Copyright 2023 The TensorFlow Datasets Authors.
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#     http://www.apache.org/licenses/LICENSE-2.0
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"""CIFAR100-N dataset."""

from __future__ import annotations

import collections
import os

from etils import epath
import numpy as np
from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow as tf
import tensorflow_datasets.public_api as tfds

# Shared constants
_CIFAR_IMAGE_SIZE = 32
_CIFAR_IMAGE_SHAPE = (_CIFAR_IMAGE_SIZE, _CIFAR_IMAGE_SIZE, 3)

_DESCRIPTION = """
A re-labeled version of CIFAR-100 with real human annotation errors. For every 
pair (image, label) in the original CIFAR-100 train set, it provides an 
additional label given by a real human annotator. 
"""

_CITATION = """
@inproceedings{wei2022learning,
  title={Learning with Noisy Labels Revisited: A Study Using Real-World Human 
  Annotations},
  author={Jiaheng Wei and Zhaowei Zhu and Hao Cheng and Tongliang Liu and Gang 
  Niu and Yang Liu},
  booktitle={International Conference on Learning Representations},
  year={2022},
  url={https://openreview.net/forum?id=TBWA6PLJZQm}
}
"""


class Cifar100N(tfds.core.GeneratorBasedBuilder):
  """DatasetBuilder for CIFAR-10N dataset."""

  MANUAL_DOWNLOAD_INSTRUCTIONS = """
  Download 'side_info_cifar100N.csv', 'CIFAR-100_human_ordered.npy' and
  'image_order_c100.npy' from https://github.com/UCSC-REAL/cifar-10-100n.
  
  Then convert 'CIFAR-100_human_ordered.npy' into a CSV file 
  'CIFAR-100_human_annotations.csv'. This can be done with the following code:
  
  ```
  import numpy as np
  import pandas as pd
  from tensorflow_datasets.core.utils.lazy_imports_utils import tensorflow as tf
  
  human_labels_np_path = '<local_path>/CIFAR-100_human_ordered.npy'
  human_labels_csv_path = '<local_path>/CIFAR-100_human_annotations.csv'

  with tf.io.gfile.GFile(human_labels_np_path, "rb") as f:
    human_annotations = np.load(f, allow_pickle=True)

  df = pd.DataFrame(human_annotations[()])

  with tf.io.gfile.GFile(human_labels_csv_path, "w") as f:
    df.to_csv(f, index=False)
  ```
  """

  VERSION = tfds.core.Version('1.0.1')
  RELEASE_NOTES = {
      '1.0.0': 'Initial release.',
      '1.0.1': 'Fixed correspondence between annotations and images.',
  }

  def _info(self) -> tfds.core.DatasetInfo:
    """Returns the dataset metadata."""
    return tfds.core.DatasetInfo(
        builder=self,
        description=_DESCRIPTION,
        features=tfds.features.FeaturesDict({
            'id': tfds.features.Text(),
            'image': tfds.features.Image(shape=_CIFAR_IMAGE_SHAPE),
            'label': tfds.features.ClassLabel(num_classes=100),
            'coarse_label': tfds.features.ClassLabel(num_classes=20),
            'noise_label': tfds.features.ClassLabel(num_classes=100),
            'worker_id': np.int64,
            'worker_time': np.float32,
        }),
        supervised_keys=None,
        homepage='https://www.cs.toronto.edu/~kriz/cifar.html',
        citation=_CITATION,
    )

  @property
  def _cifar_info(self):
    return CifarInfo(
        name=self.name,
        url='https://www.cs.toronto.edu/~kriz/cifar-100-binary.tar.gz',
        train_files=['train.bin'],
        test_files=['test.bin'],
        prefix='cifar-100-binary/',
        label_files=['coarse_label_names.txt', 'fine_label_names.txt'],
        label_keys=['coarse_label', 'label'],
        human_label_path='CIFAR-100_human_annotations.csv',
        side_info_path='side_info_cifar100N.csv',
        annotations_order_path='image_order_c100.npy',
    )

  def _split_generators(self, dl_manager):
    """Returns SplitGenerators."""
    cifar_path = dl_manager.download_and_extract(self._cifar_info.url)
    cifar_info = self._cifar_info

    cifar_path = os.path.join(cifar_path, cifar_info.prefix)

    dl_paths = {
        'human_labels': dl_manager.manual_dir / cifar_info.human_label_path,
        'side_info': dl_manager.manual_dir / cifar_info.side_info_path,
        'annotations_order': (
            dl_manager.manual_dir / cifar_info.annotations_order_path
        ),
    }

    # Load the label names
    for label_key, label_file in zip(
        cifar_info.label_keys, cifar_info.label_files
    ):
      labels_path = os.path.join(cifar_path, label_file)
      with epath.Path(labels_path).open() as label_f:
        label_names = [name for name in label_f.read().split('\n') if name]
      self.info.features[label_key].names = label_names

    # Define the splits
    def gen_filenames(filenames):
      for f in filenames:
        yield os.path.join(cifar_path, f)

    return {
        'train': self._generate_examples(
            'train_', gen_filenames(cifar_info.train_files), dl_paths
        ),
        'test': self._generate_examples(
            'test_', gen_filenames(cifar_info.test_files), dl_paths
        ),
    }

  def _generate_examples(self, split_prefix, filepaths, dl_paths):
    """Generate CIFAR-100N examples as dicts.

    Uses self._cifar_info as configuration.

    Args:
      split_prefix (str): Prefix that identifies the split (e.g. "tr" or "te").
      filepaths (list[str]): The files to use to generate the data.
      dl_paths (dict[str, str]): Paths to human_labels and side_info

    Yields:
      The cifar examples, as defined in the dataset info features.
    """
    label_keys = self._cifar_info.label_keys
    index = 0  # Using index as key since data is always loaded in same order.

    if 'train' in split_prefix:
      human_labels = _load_human_labels(dl_paths['human_labels'])
      noise_label = human_labels['noise_label']

      side_info = _load_side_info(dl_paths['side_info'])
      worker_id = side_info['worker_id']
      worker_time = side_info['worker_time']

      annotations_order = _load_annotations_order(dl_paths['annotations_order'])

    for path in filepaths:
      for labels, np_image in _load_data(path, len(label_keys)):
        record = dict(zip(label_keys, labels))
        # Note: "id" is only provided for the user convenience. To shuffle the
        # dataset we use `index`, so that the sharding is compatible with
        # earlier versions.
        record['id'] = '{}{:05d}'.format(split_prefix, index)
        record['image'] = np_image

        if 'train' in split_prefix:
          # Note: The human labels are provided according to default shuffling
          # of 'cifar100'. We need to invert the shuffling to assign the right
          # human label to each example.
          annotations_index = np.where(annotations_order == index)[0][0]

          record['noise_label'] = noise_label[annotations_index]
          # Worker metadata is shared every 5 samples
          record['worker_id'] = worker_id[index // 5]
          record['worker_time'] = worker_time[index // 5]
        else:
          # There is no annotator metadata for test split
          record['noise_label'] = -1
          record['worker_id'] = -1
          record['worker_time'] = -1

        yield index, record
        index += 1


class CifarInfo(
    collections.namedtuple(
        '_CifarInfo',
        [
            'name',
            'url',
            'prefix',
            'train_files',
            'test_files',
            'label_files',
            'label_keys',
            'human_label_path',
            'side_info_path',
            'annotations_order_path',
        ],
    )
):
  """Contains the information necessary to generate a CIFAR dataset.

  Attributes:
    name (str): name of dataset.
    url (str): data URL.
    prefix (str): path prefix within the downloaded and extracted file to look
      for `train_files` and `test_files`.
    train_files (list<str>): name of training files within `prefix`.
    test_files (list<str>): name of test files within `prefix`.
    label_files (list<str>): names of the label files in the data.
    label_keys (list<str>): names of the label keys in the data.
    human_label_path (str): path to human annotations.
    side_info_path (str): path to metadata about annotations.
    annotations_order_path (str): path to annotation-image order correspondence.
  """


def _load_data(path, labels_number=1):
  """Yields (labels, np_image) tuples."""
  with tf.io.gfile.GFile(path, 'rb') as f:
    data = f.read()
  offset = 0
  max_offset = len(data) - 1
  while offset < max_offset:
    labels = np.frombuffer(
        data, dtype=np.uint8, count=labels_number, offset=offset
    ).reshape((labels_number,))
    # 1 byte per label, 1024 * 3 = 3072 bytes for the image.
    offset += labels_number
    img = (
        np.frombuffer(data, dtype=np.uint8, count=3072, offset=offset)
        .reshape((3, _CIFAR_IMAGE_SIZE, _CIFAR_IMAGE_SIZE))
        .transpose((1, 2, 0))
    )
    offset += 3072
    yield labels, img


def _load_annotations_order(path):
  """Loads index mapping between the annotation files and the CIFAR100 binaries."""
  with tf.io.gfile.GFile(path, 'rb') as f:
    annotations_order = np.load(f)
  return annotations_order


def _load_side_info(path):
  """Loads information from side_info_cifar100N.csv."""
  side_info_key_map = {
      1: 'worker_id',
      2: 'worker_time',
  }
  side_info_array = np.genfromtxt(
      tf.io.gfile.GFile(path), delimiter=',', skip_header=1
  )
  side_info = {}
  for key in side_info_key_map:
    side_info[side_info_key_map[key]] = side_info_array[:, key]
  return side_info


def _load_human_labels(path):
  """Loads information from side_info_cifar100N.csv."""
  with tf.io.gfile.GFile(path, 'r') as f:
    human_labels_array = np.genfromtxt(f, delimiter=',', skip_header=1)
  human_labels = {}
  human_labels['noise_label'] = human_labels_array[:, 1]
  return human_labels
