import os
import json
import shutil
import string
import tifffile
import datasets

import numpy as np
import pandas as pd

class_sets = {
        19: [
            'Urban fabric',
            'Industrial or commercial units',
            'Arable land',
            'Permanent crops',
            'Pastures',
            'Complex cultivation patterns',
            'Land principally occupied by agriculture, with significant areas of'
            ' natural vegetation',
            'Agro-forestry areas',
            'Broad-leaved forest',
            'Coniferous forest',
            'Mixed forest',
            'Natural grassland and sparsely vegetated areas',
            'Moors, heathland and sclerophyllous vegetation',
            'Transitional woodland, shrub',
            'Beaches, dunes, sands',
            'Inland wetlands',
            'Coastal wetlands',
            'Inland waters',
            'Marine waters',
        ],
        43: [
            'Continuous urban fabric',
            'Discontinuous urban fabric',
            'Industrial or commercial units',
            'Road and rail networks and associated land',
            'Port areas',
            'Airports',
            'Mineral extraction sites',
            'Dump sites',
            'Construction sites',
            'Green urban areas',
            'Sport and leisure facilities',
            'Non-irrigated arable land',
            'Permanently irrigated land',
            'Rice fields',
            'Vineyards',
            'Fruit trees and berry plantations',
            'Olive groves',
            'Pastures',
            'Annual crops associated with permanent crops',
            'Complex cultivation patterns',
            'Land principally occupied by agriculture, with significant areas of'
            ' natural vegetation',
            'Agro-forestry areas',
            'Broad-leaved forest',
            'Coniferous forest',
            'Mixed forest',
            'Natural grassland',
            'Moors and heathland',
            'Sclerophyllous vegetation',
            'Transitional woodland/shrub',
            'Beaches, dunes, sands',
            'Bare rock',
            'Sparsely vegetated areas',
            'Burnt areas',
            'Inland marshes',
            'Peatbogs',
            'Salt marshes',
            'Salines',
            'Intertidal flats',
            'Water courses',
            'Water bodies',
            'Coastal lagoons',
            'Estuaries',
            'Sea and ocean',
        ],
    }

label_converter = {
        0: 0,
        1: 0,
        2: 1,
        11: 2,
        12: 2,
        13: 2,
        14: 3,
        15: 3,
        16: 3,
        18: 3,
        17: 4,
        19: 5,
        20: 6,
        21: 7,
        22: 8,
        23: 9,
        24: 10,
        25: 11,
        31: 11,
        26: 12,
        27: 12,
        28: 13,
        29: 14,
        33: 15,
        34: 15,
        35: 16,
        36: 16,
        38: 17,
        39: 17,
        40: 18,
        41: 18,
        42: 18,
    }

S2_MEAN = [752.40087073, 884.29673756, 1144.16202635, 1297.47289228, 1624.90992062, 2194.6423161, 2422.21248945, 2517.76053101, 2581.64687018, 2645.51888987, 2368.51236873, 1805.06846033]
S2_STD = [1108.02887453, 1155.15170768, 1183.6292542, 1368.11351514, 1370.265037, 1355.55390699, 1416.51487101, 1474.78900051, 1439.3086061, 1582.28010962, 1455.52084939, 1343.48379601]

S1_MEAN = [-12.54847273, -20.19237134]
S1_STD = [5.25697717, 5.91150917]

parts = [f"a{letter}" for letter in string.ascii_lowercase]
parts.extend([f"b{letter}" for letter in string.ascii_lowercase[:8]]) 

class BigEarthNetDataset(datasets.GeneratorBasedBuilder):
    VERSION = datasets.Version("1.0.0")

    DATA_URL = [
        f"https://huggingface.co/datasets/GFM-Bench/BigEarthNet/resolve/main/data/bigearthnet_part_{part}"
        for part in parts
    ]

    metadata = {
        "s2c": {
            "bands":["B1", "B2", "B3", "B4", "B5", "B6", "B7", "B8", "B8A", "B9", "B11", "B12"],
            "channel_wv": [442.7, 492.4, 559.8, 664.6, 704.1, 740.5, 782.8, 832.8, 864.7, 945.1, 1613.7, 2202.4],
            "mean": S2_MEAN,
            "std": S2_STD
        },
        "s1": {
            "bands": ["VV", "VH"],
            "channel_wv": [5500, 5700],
            "mean": S1_MEAN,
            "std": S1_STD
        }
    }

    SIZE = HEIGHT = WIDTH = 120

    NUM_CLASSES = 19

    spatial_resolution = 10

    def __init__(self, *args, **kwargs):
        self.class2idx = {c: i for i, c in enumerate(class_sets[43])}

        super().__init__(*args, **kwargs)

    def _info(self):
        metadata = self.metadata
        metadata['size'] = self.SIZE
        metadata['num_classes'] = self.NUM_CLASSES
        metadata['spatial_resolution'] = self.spatial_resolution
        return datasets.DatasetInfo(
            description=json.dumps(metadata),
            features=datasets.Features({
                "optical": datasets.Array3D(shape=(12, self.HEIGHT, self.WIDTH), dtype="float32"),
                "radar": datasets.Array3D(shape=(2, self.HEIGHT, self.WIDTH), dtype="float32"),
                "optical_channel_wv": datasets.Sequence(datasets.Value("float32")),
                "radar_channel_wv": datasets.Sequence(datasets.Value("float32")),
                "label": datasets.Sequence(datasets.Value("float32"), length=self.NUM_CLASSES),
                "spatial_resolution": datasets.Value("int32"),
            }),
        )

    def _split_generators(self, dl_manager):
        if isinstance(self.DATA_URL, list):
            try:
                downloaded_files = dl_manager.download(self.DATA_URL)
                print(f"downloaded files: {downloaded_files}")
                combined_file = os.path.join(dl_manager.download_config.cache_dir, "combined.tar.gz") 
                print(f"copying files to {combined_file}")
                target_dir = os.path.dirname(combined_file)
                os.makedirs(target_dir, exist_ok=True)  # Create only the directory                
                with open(combined_file, 'wb') as outfile:
                    counter = 0 
                    for part_file in downloaded_files:
                        print(f"copying {counter}-th file: {part_file}")
                        with open(part_file, 'rb') as infile:
                            shutil.copyfileobj(infile, outfile)
                        counter += 1
                print(f"extacting from {combined_file}")
                data_dir = dl_manager.extract(combined_file)
                os.remove(combined_file)
                print(f"data_dir: {data_dir}")
            except Exception as e:
                # Print the error message
                print(f"{e}, setting data_dir to None")
                data_dir = None
        else:
            data_dir = dl_manager.download_and_extract(self.DATA_URL)

        return [
            datasets.SplitGenerator(
                name="train",
                gen_kwargs={
                    "split": 'train',
                    "data_dir": data_dir, 
                },
            ),
            datasets.SplitGenerator(
                name="val",
                gen_kwargs={
                    "split": 'val',
                    "data_dir": data_dir,
                },
            ),
            datasets.SplitGenerator(
                name="test",
                gen_kwargs={
                    "split": 'test',
                    "data_dir": data_dir,
                },
            )
        ]

    def _generate_examples(self, split, data_dir):
        optical_channel_wv = np.array(self.metadata["s2c"]["channel_wv"])
        radar_channel_wv = np.array(self.metadata["s1"]["channel_wv"])
        spatial_resolution = self.spatial_resolution

        data_dir = os.path.join(data_dir, "BigEarthNet")
        metadata = pd.read_csv(os.path.join(data_dir, "metadata.csv"))
        metadata = metadata[metadata["split"] == split].reset_index(drop=True)

        for index, row in metadata.iterrows():
            optical_path = os.path.join(data_dir, row.optical_path)
            optical = self._read_image(optical_path).astype(np.float32) # CxHxW

            radar_path = os.path.join(data_dir, row.radar_path)
            radar = self._read_image(radar_path).astype(np.float32)

            label_path = os.path.join(data_dir, row.label_path)
            label = self._load_label(label_path)

            sample = {
                "optical": optical,
                "radar": radar,
                "optical_channel_wv": optical_channel_wv,
                "radar_channel_wv": radar_channel_wv,
                "label": label,
                "spatial_resolution": spatial_resolution,
            }

            yield f"{index}", sample
    
    def _load_label(self, label_path):
        with open(label_path) as f:
            labels = json.load(f)['labels']
        indices =[self.class2idx[label] for label in labels]
        indices_optional = [label_converter.get(idx) for idx in indices]
        indices = [idx for idx in indices_optional if idx is not None]
        label = np.zeros(19, dtype=np.int64)
        label[indices] = 1
        return label
    
    def _read_image(self, image_path):
        """Read tiff image from image_path
        Args:
            image_path: 
                Image path to read from

        Return:
            image: 
                C, H, W numpy array image
        """
        image = tifffile.imread(image_path)
        image = np.transpose(image, (2, 0, 1))

        return image