import pydicom
from PIL import Image
import numpy as np
import io
import datasets
import gdown
import re
import s3fs
import random

manifest_url = "https://drive.google.com/uc?id=1JBkQTXeieyN9_6BGdTF_DDlFFyZrGyU6"
manifest_file = gdown.download(manifest_url, 'manifest_file.s5cmd', quiet=False)
fs = s3fs.S3FileSystem(anon=True)

_DESCRIPTION = """
This dataset, curated from the comprehensive collection by the National Cancer Institute (NCI)
and hosted on AWS, contains over 900,000 colon CT images, along with the corresponding patients'
information. It is designed to help researcher in developing advanced machine learning models
for in-depth studies in colon cancer.
"""
_HOMEPAGE = "https://imaging.datacommons.cancer.gov/"
_LICENSE = "https://fairsharing.org/FAIRsharing.0b5a1d"
_CITATION = """\
@article{fedorov2021nci,
  title={NCI imaging data commons},
  author={Fedorov, Andrey and Longabaugh, William JR and Pot, David
  and Clunie, David A and Pieper, Steve and Aerts, Hugo JWL and
  Homeyer, Andr{\'e} and Lewis, Rob and Akbarzadeh, Afshin and
  Bontempi, Dennis and others},
  journal={Cancer research},
  volume={81},
  number={16},
  pages={4188--4193},
  year={2021},
  publisher={AACR}
}
"""

class ColonCancerCTDataset(datasets.GeneratorBasedBuilder):
  """This dataset script retrieves the dataset using a manifest file from the original dataset's
  homepage. The file lists the S3 paths for each series of CT images and metadata, guiding the download
  from AWS. After processing the original content, this dataset will contian the image of the colonography, 
  image type, study date, series date, manufacturer details, study descriptions, series descriptions, 
  and patient demographics including sex, age, and pregnancy status.
  """
  VERSION = datasets.Version("1.1.0")

  def _info(self):
    """Returns DatasetInfo."""
    # This method specifies the datasets.DatasetInfo object which contains informations and typings for the dataset
    return datasets.DatasetInfo(
        description=_DESCRIPTION,
        features=datasets.Features(
            {
                "image": datasets.Image(),
                "ImageType": datasets.Sequence(datasets.Value('string')), 
                "StudyDate": datasets.Value('string'), 
                "SeriesDate": datasets.Value('string'),
                "Manufacturer": datasets.Value('string'),
                "StudyDescription": datasets.Value('string'),
                "SeriesDescription": datasets.Value('string'),
                "PatientSex": datasets.Value('string'),
                "PatientAge": datasets.Value('string'),
                "PregnancyStatus": datasets.Value('string'),
                "BodyPartExamined": datasets.Value('string'),
            }),
        homepage = _HOMEPAGE,
        license = _LICENSE,
        citation = _CITATION
        )

  def _split_generators(self, dl_manager):
    """Returns a list of SplitGenerators."""
    # This method is tasked with extracting the S3 paths of the data and defining the splits 
    # by shuffling and randomly partitioning the paths in the manifest file.
    s3_series_paths = []
    s3_individual_paths = []
    with open(manifest_file, 'r') as file:
      for line in file:
          match = re.search(r'cp (s3://[\S]+) .', line)
          if match:
              s3_series_paths.append(match.group(1)[:-2]) # Deleting the '/*' in directories
    for series in s3_series_paths:
        for content in fs.ls(series):
          s3_individual_paths.append(fs.info(content)['Key']) # Retrieve the individual DICOM file's S3 path

    random.shuffle(s3_individual_paths) # Randomly shuffles the paths for partitioning

    # Define the split sizes
    train_size = int(0.7 * len(s3_individual_paths))
    val_size = int(0.15 * len(s3_individual_paths))
    # Split the paths into train, validation, and test sets
    train_paths = s3_individual_paths[:train_size]
    val_paths = s3_individual_paths[train_size:train_size + val_size]
    test_paths = s3_individual_paths[train_size + val_size:]

    return [
        datasets.SplitGenerator(
            name=datasets.Split.TRAIN,
            gen_kwargs={
                "paths": train_paths,
                "split": "train"
            },
        ),
        datasets.SplitGenerator(
            name=datasets.Split.VALIDATION,
            gen_kwargs={
                "paths": val_paths,
                "split": "dev"
            },
        ),
        datasets.SplitGenerator(
            name=datasets.Split.TEST,
            gen_kwargs={
                "paths": test_paths,
                "split": "test"
            },
        ),
    ]

  def _generate_examples(self, paths, split):
    """Yields examples."""
    # This method will yield examples, i.e. rows in the dataset.
    for path in paths:
      key = path
      with fs.open(path, 'rb') as f:
        dicom_data = pydicom.dcmread(f)
        pixel_array = dicom_data.pixel_array
        # Converting pixel array into PNG image
        # Adjust for MONOCHROME1 to invert the grayscale values
        if dicom_data.PhotometricInterpretation == "MONOCHROME1":
          pixel_array = np.max(pixel_array) - pixel_array
        # Normalize or scale 16-bit or other depth images to 8-bit
        if pixel_array.dtype != np.uint8:
            pixel_array = (np.divide(pixel_array, np.max(pixel_array)) * 255).astype(np.uint8)
        # Convert to RGB if it is not already (e.g., for color images)
        if len(pixel_array.shape) == 2:
            im = Image.fromarray(pixel_array, mode="L")  # L mode is for grayscale
        elif len(pixel_array.shape) == 3 and pixel_array.shape[2] in [3, 4]:
            im = Image.fromarray(pixel_array, mode="RGB")
        else:
            raise ValueError("Unsupported DICOM image format")
        with io.BytesIO() as output:
            im.save(output, format="PNG")
            png_image = output.getvalue()
        # Extracting metadata
        ImageType = dicom_data.get("ImageType", "")
        StudyDate = dicom_data.get("StudyDate", "")
        SeriesDate = dicom_data.get("SeriesDate", "")
        Manufacturer = dicom_data.get("Manufacturer", "")
        StudyDescription = dicom_data.get("StudyDescription", "")
        SeriesDescription = dicom_data.get("SeriesDescription", "")
        PatientSex = dicom_data.get("PatientSex", "")
        PatientAge = dicom_data.get("PatientAge", "")
        PregnancyStatus = dicom_data.get("PregnancyStatus", "")
        if PregnancyStatus == None:
           PregnancyStatus = "None"
        else:
           PregnancyStatus = "Yes"
        BodyPartExamined = dicom_data.get("BodyPartExamined", "")
        yield key, {"image": png_image, 
                    "ImageType": ImageType, 
                    "StudyDate": StudyDate, 
                    "SeriesDate": SeriesDate, 
                    "Manufacturer": Manufacturer, 
                    "StudyDescription": StudyDescription, 
                    "SeriesDescription": SeriesDescription,
                    "PatientSex": PatientSex, 
                    "PatientAge": PatientAge, 
                    "PregnancyStatus": PregnancyStatus, 
                    "BodyPartExamined": BodyPartExamined}