import os
from pathlib import Path
import datasets
from datasets import GeneratorBasedBuilder, SplitGenerator, DatasetInfo, Features, Value, BuilderConfig

_CITATION = ""
_DESCRIPTION = "DF2K is a combined dataset of DIV2K, Flickr2K and OST datasets commonly used for super-resolution tasks. It contains high resolution images and their low resolution counterparts generated using bicubic and unknown downsampling."
_HOMEPAGE = ""
_LICENSE = ""

class DF2KOSTDataset(GeneratorBasedBuilder):
    BUILDER_CONFIGS = [
        # LR Bicubic variants
        BuilderConfig(name="train-lr_bicubic-x2", description="Training set with bicubic downsampling x2"),
        BuilderConfig(name="train-lr_bicubic-x3", description="Training set with bicubic downsampling x3"),
        BuilderConfig(name="train-lr_bicubic-x4", description="Training set with bicubic downsampling x4"),
        
        # LR Unknown variants
        BuilderConfig(name="train-lr_unknown-x2", description="Training set with unknown downsampling x2"),
        BuilderConfig(name="train-lr_unknown-x3", description="Training set with unknown downsampling x3"),
        BuilderConfig(name="train-lr_unknown-x4", description="Training set with unknown downsampling x4"),
        
        # DIV2K specific subsets
        BuilderConfig(name="div2k-train", description="DIV2K training set"),
        BuilderConfig(name="div2k-train-lr_bicubic-x2", description="DIV2K training set with bicubic downsampling x2"),
        BuilderConfig(name="div2k-train-lr_bicubic-x3", description="DIV2K training set with bicubic downsampling x3"),
        BuilderConfig(name="div2k-train-lr_bicubic-x4", description="DIV2K training set with bicubic downsampling x4"),
        BuilderConfig(name="div2k-train-lr_unknown-x2", description="DIV2K training set with unknown downsampling x2"),
        BuilderConfig(name="div2k-train-lr_unknown-x3", description="DIV2K training set with unknown downsampling x3"),
        BuilderConfig(name="div2k-train-lr_unknown-x4", description="DIV2K training set with unknown downsampling x4"),
        BuilderConfig(name="div2k-valid", description="DIV2K validation set"),
        
        # Flickr2K specific subsets
        BuilderConfig(name="flickr2k-train", description="Flickr2K training set"),
        BuilderConfig(name="flickr2k-train-lr_bicubic-x2", description="Flickr2K training set with bicubic downsampling x2"),
        BuilderConfig(name="flickr2k-train-lr_bicubic-x3", description="Flickr2K training set with bicubic downsampling x3"),
        BuilderConfig(name="flickr2k-train-lr_bicubic-x4", description="Flickr2K training set with bicubic downsampling x4"),
        BuilderConfig(name="flickr2k-train-lr_unknown-x2", description="Flickr2K training set with unknown downsampling x2"),
        BuilderConfig(name="flickr2k-train-lr_unknown-x3", description="Flickr2K training set with unknown downsampling x3"),
        BuilderConfig(name="flickr2k-train-lr_unknown-x4", description="Flickr2K training set with unknown downsampling x4"),
        
        # OST specific subsets
        BuilderConfig(name="ost-train", description="OST training set"),
        BuilderConfig(name="ost-train-lr_bicubic-x2", description="OST training set with bicubic downsampling x2"),
        BuilderConfig(name="ost-train-lr_bicubic-x3", description="OST training set with bicubic downsampling x3"),
        BuilderConfig(name="ost-train-lr_bicubic-x4", description="OST training set with bicubic downsampling x4"),
        BuilderConfig(name="ost-train-lr_unknown-x2", description="OST training set with unknown downsampling x2"),
        BuilderConfig(name="ost-train-lr_unknown-x3", description="OST training set with unknown downsampling x3"),
        BuilderConfig(name="ost-train-lr_unknown-x4", description="OST training set with unknown downsampling x4"),
        BuilderConfig(name="ost-valid", description="OST validation set"),
    ]

    def _info(self) -> DatasetInfo:
        return DatasetInfo(
            description=_DESCRIPTION,
            citation=_CITATION,
            homepage=_HOMEPAGE,
            license=_LICENSE,
            features=Features({
                "image": datasets.Image(),
                "source": Value("string"),
                "split_type": Value("string"),
                "file_name": Value("string"),
                "path": Value("string"),
            }),
        )

    def _split_generators(self, dl_manager) -> list[SplitGenerator]:
        base_dir = Path(dl_manager.manual_dir)

        # Default splits (always available)
        if not self.config.name:
            return [
                SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/HR"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/HR"), os.path.join(base_dir, "DF2K+OST/OST/train/HR")], "source": "DF2K+OST", "split_type": "train"}),
                SplitGenerator(name=datasets.Split.VALIDATION, gen_kwargs={"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/valid"), os.path.join(base_dir, "DF2K+OST/OST/valid")], "source": "DF2K+OST", "split_type": "valid"}),
            ]

        # Subset configurations
        config_map = {
            # LR Bicubic variants
            "train-lr_bicubic-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x2"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x2"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x2")], "source": "DF2K+OST", "split_type": "train-lr_bicubic-x2"},
            "train-lr_bicubic-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x3"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x3"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x3")], "source": "DF2K+OST", "split_type": "train-lr_bicubic-x3"},
            "train-lr_bicubic-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x4"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x4"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x4")], "source": "DF2K+OST", "split_type": "train-lr_bicubic-x4"},
            
            # LR Unknown variants
            "train-lr_unknown-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x2"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x2"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x2")], "source": "DF2K+OST", "split_type": "train-lr_unknown-x2"},
            "train-lr_unknown-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x3"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x3"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x3")], "source": "DF2K+OST", "split_type": "train-lr_unknown-x3"},
            "train-lr_unknown-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x4"), os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x4"), os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x4")], "source": "DF2K+OST", "split_type": "train-lr_unknown-x4"},
            
            # DIV2K specific subsets
            "div2k-train": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/HR")], "source": "DIV2K", "split_type": "train"},
            "div2k-train-lr_bicubic-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x2")], "source": "DIV2K", "split_type": "train-lr_bicubic-x2"},
            "div2k-train-lr_bicubic-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x3")], "source": "DIV2K", "split_type": "train-lr_bicubic-x3"},
            "div2k-train-lr_bicubic-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_bicubic/x4")], "source": "DIV2K", "split_type": "train-lr_bicubic-x4"},
            "div2k-train-lr_unknown-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x2")], "source": "DIV2K", "split_type": "train-lr_unknown-x2"},
            "div2k-train-lr_unknown-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x3")], "source": "DIV2K", "split_type": "train-lr_unknown-x3"},
            "div2k-train-lr_unknown-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/train/LR_unknown/x4")], "source": "DIV2K", "split_type": "train-lr_unknown-x4"},
            "div2k-valid": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/DIV2K/valid")], "source": "DIV2K", "split_type": "valid"},
            
            # Flickr2K specific subsets
            "flickr2k-train": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/HR")], "source": "Flickr2k", "split_type": "train"},
            "flickr2k-train-lr_bicubic-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x2")], "source": "Flickr2k", "split_type": "train-lr_bicubic-x2"},
            "flickr2k-train-lr_bicubic-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x3")], "source": "Flickr2k", "split_type": "train-lr_bicubic-x3"},
            "flickr2k-train-lr_bicubic-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_bicubic/x4")], "source": "Flickr2k", "split_type": "train-lr_bicubic-x4"},
            "flickr2k-train-lr_unknown-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x2")], "source": "Flickr2k", "split_type": "train-lr_unknown-x2"},
            "flickr2k-train-lr_unknown-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x3")], "source": "Flickr2k", "split_type": "train-lr_unknown-x3"},
            "flickr2k-train-lr_unknown-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/Flickr2k/train/LR_unknown/x4")], "source": "Flickr2k", "split_type": "train-lr_unknown-x4"},
            
            # OST specific subsets
            "ost-train": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/HR")], "source": "OST", "split_type": "train"},
            "ost-train-lr_bicubic-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x2")], "source": "OST", "split_type": "train-lr_bicubic-x2"},
            "ost-train-lr_bicubic-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x3")], "source": "OST", "split_type": "train-lr_bicubic-x3"},
            "ost-train-lr_bicubic-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_bicubic/x4")], "source": "OST", "split_type": "train-lr_bicubic-x4"},
            "ost-train-lr_unknown-x2": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x2")], "source": "OST", "split_type": "train-lr_unknown-x2"},
            "ost-train-lr_unknown-x3": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x3")], "source": "OST", "split_type": "train-lr_unknown-x3"},
            "ost-train-lr_unknown-x4": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/train/LR_unknown/x4")], "source": "OST", "split_type": "train-lr_unknown-x4"},
            "ost-valid": {"data_dirs": [os.path.join(base_dir, "DF2K+OST/OST/valid")], "source": "OST", "split_type": "valid"},
        }

        # Return the specific subset configuration
        if self.config.name in config_map:
            config = config_map[self.config.name]
            return [
                SplitGenerator(
                    name=datasets.Split.TRAIN,
                    gen_kwargs=config
                )
            ]
        else:
            raise ValueError(f"Unknown config name: {self.config.name}")

    def _generate_examples(self, data_dirs, source, split_type):
        idx = 0
        for dir_path in data_dirs:
            dir_path = Path(dir_path)
            for file_path in dir_path.glob("**/*"):
                if file_path.is_file() and file_path.suffix.lower() in [".jpg", ".jpeg", ".png", ".bmp", ".webp"]:
                    yield idx, {
                        "image": str(file_path),
                        "source": source,
                        "split_type": split_type,
                        "file_name": file_path.name,
                        "path": str(file_path),
                    }
                    idx += 1