from dataclasses import dataclass
from pathlib import Path
from typing import Optional

import pyarrow as pa

import datasets
from datasets.tasks import ImageClassification


logger = datasets.utils.logging.get_logger(__name__)


@dataclass
class ImageFolderConfig(datasets.BuilderConfig):
    """BuilderConfig for ImageFolder."""

    features: Optional[datasets.Features] = None

    @property
    def schema(self):
        return pa.schema(self.features.type) if self.features is not None else None


class ImageFolder(datasets.GeneratorBasedBuilder):

    BUILDER_CONFIG_CLASS = ImageFolderConfig

    def _info(self):
        folder=None
        if isinstance(self.config.data_files, str):
            folder = self.config.data_files
        elif isinstance(self.config.data_files, dict):
            folder = self.config.data_files.get('train', None)
        if folder is None:
            raise RuntimeError()
        classes = sorted([x.name.lower() for x in Path(folder).glob('*/**')])
        return datasets.DatasetInfo(
            features=datasets.Features(
                {"image_file_path": datasets.Value("string"), "labels": datasets.Value("string")}
            ),
            task_templates=[datasets.tasks.ImageClassification(image_file_path_column="image_file_path", label_column="labels", labels=classes)]
        )

    def _split_generators(self, dl_manager):
        if not self.config.data_files:
            raise ValueError(f"At least one data file must be specified, but got data_files={self.config.data_files}")

        data_files = self.config.data_files
        if isinstance(data_files, str):
            folder = data_files
            return [datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"archive_path": folder})]
        splits = []
        for split_name, folder in data_files.items():
            splits.append(datasets.SplitGenerator(name=split_name, gen_kwargs={"archive_path": folder}))
        return splits

    def _generate_examples(self, archive_path):
        logger.info("generating examples from = %s", archive_path)
        extensions = {".jpg", ".jpeg", ".png", ".ppm", ".bmp", ".pgm", ".tif", ".tiff", ".webp"}
        for i, path in enumerate(Path(archive_path).glob("**/*")):
            if path.suffix in extensions:
                yield i, {"image_file_path": path.as_posix(), "labels": path.parent.name.lower()}