import numpy as np
import json
from jsonargparse import CLI
import pandas as pd

import pyJHTDB
import pyJHTDB.dbinfo
from tqdm import tqdm
from pathlib import Path
from itertools import chain
import zipfile


def get_filename(
    time_step: int,
    start: np.ndarray,  # [x, y, z]
    end: np.ndarray,  # [x, y, z]
    step: np.ndarray,  # [x, y, z]
    filter_width: int,
):
    """Serializes jhtdb params into a filename."""
    return "{0}_{1}_{2}_{3}_{4}_{5}_{6}_{7}_{8}_{9}_{10}.npy".format(
        time_step,
        start[0],
        start[1],
        start[2],
        end[0],
        end[1],
        end[2],
        step[0],
        step[1],
        step[2],
        filter_width,
    )


def download_jhtdb(
    loader: pyJHTDB.libJHTDB,
    time_step: int,
    start: np.ndarray,
    end: np.ndarray,
    step: np.ndarray,
    filter_width: int,
    path: Path,
    dataset: str = "isotropic1024coarse",
    field: str = "u",
):
    """
    :param loader: pyJHTDB.libJHTDB object
    :param time_step: time step to download
    :param start: start [x, y, z] of the cutout
    :param end: end [x, y, z] of the cutout
    :param step: step size of the cutout
    :param filter_width: filter width of the cutout
    :param path: path to save the data
    :param dataset: dataset to download from. Default is "isotropic1024coarse"
    :param field: velocity ("u") or pressure ("p") field
    """
    if not path.exists():
        results: np.ndarray = loader.getCutout(
            data_set=dataset,
            field=field,
            time_step=time_step,
            start=start,
            end=end,
            step=step,
            filter_width=filter_width,
        )
        if results is None:
            raise Exception("Could not download data from JHTDB")
        results = np.rollaxis(
            results, -1, 0
        )  # Move the [x, y, z] dimensions to the front
        np.save(path, results)
    return np.load(path)


def download_all(params: dict, loader: pyJHTDB.libJHTDB):
    """Download all the data from the JHTDB database.
    TODO: parallelize this function
    """
    for p in tqdm(params):
        download_jhtdb(loader=loader, **p)


def get_params(
    total_samples: int,
    domain_size: int,
    lr_factor: int,
    time_range: list[int],
    window_size: int,
) -> tuple[dict, dict]:
    dt = np.arange(window_size) - window_size // 2
    time_steps_hr = np.random.randint(time_range[0], time_range[1], size=total_samples)
    # reshape time_steps to (total_samples, len(dt)) so that for each i we can get time_steps[i] + dt[j]
    time_steps_lr = np.repeat(time_steps_hr[:, np.newaxis], len(dt), axis=1) + dt
    # time_steps.shape = [total_samples, window_size]
    starts = np.random.randint(1, 1024 - domain_size, size=(total_samples, 3))
    ends = starts + domain_size - 1
    all_params_lr = [
        [
            {
                "time_step": time_steps_lr[i, j],
                "start": starts[i],
                "end": ends[i],
                "step": np.full(3, lr_factor, dtype=int),
                "filter_width": lr_factor,
            }
            for j in range(len(dt))
        ]
        for i in range(total_samples)
    ]
    all_params_hr = [
        {
            "time_step": time_steps_hr[i],
            "start": starts[i],
            "end": ends[i],
            "step": np.ones(3, dtype=int),
            "filter_width": 1,
        }
        for i in range(total_samples)
    ]
    return all_params_lr, all_params_hr


def download_generic(
    total_samples: int,
    domain_size: int,
    lr_factor: int,
    time_range: tuple[int, int],
    window_size: int,
    tmp_data_dir: Path,
    token: str,
):
    """Download all the data from the JHTDB database."""
    # initialize runner
    lJHTDB = pyJHTDB.libJHTDB()
    lJHTDB.initialize()
    lJHTDB.add_token(token)
    tmp_data_dir.mkdir(parents=True, exist_ok=True)

    all_params_lr, all_params_hr = get_params(
        total_samples, domain_size, lr_factor, time_range, window_size
    )
    # add path to all the params
    all_params_hr = [
        dict(p, path=tmp_data_dir / get_filename(**p)) for p in all_params_hr
    ]
    all_params_lr = [
        [dict(p, path=tmp_data_dir / get_filename(**p)) for p in lr]
        for lr in all_params_lr
    ]

    # all_params_lr.shape = [total_samples, window_size]
    # all_params_hr.shape = [total_samples]
    # flatten nested params
    all_params = list(chain.from_iterable(all_params_lr)) + all_params_hr
    download_all(all_params, lJHTDB)
    return all_params_lr, all_params_hr, all_params


def make_jhtdb_dataset(
    name: str,
    total_samples: int = 128,
    train_split: float = 0.8,
    val_split: float = 0.1,
    test_split: float = 0.1,
    domain_size: int = 64,
    lr_factor: int = 4,
    root: Path = Path("dataset/jhtdb"),
    time_range: tuple[int, int] = (2, 1023),
    window_size: int = 3,
    seed: int = 123,
    token: str = "edu.jhu.pha.turbulence.testing-201311",
) -> tuple[np.ndarray, np.ndarray]:
    """Creates low and high res dataset from JHTDB database.

    Where:
    low_res.shape = [nr_samples, 3, domain_size / lr_factor, domain_size / lr_factor, domain_size / lr_factor]
    high_res.shape = [nr_samples, 3, domain_size, domain_size, domain_size]
    And 3 corresponds to the x, y, z components of the velocity field.

    Make a dataset from the JHTDB database.
    :param: name: name of the dataset
    :param: total_samples: total number of samples to generate
    :param: train_split: percentage of samples to use for training
    :param: val_split: percentage of samples to use for validation
    :param: test_split: percentage of samples to use for testing
    :param: domain_size: size of the domain to generate
    :param: lr_factor: factor to downsample the data
    :param: root: root directory to store the dataset
    :param: time_range: range of time steps to sample from
    :param: seed: seed to generate the dataset
    :param: window_size: size of the window to sample from
    :param: token: token to access the JHTDB database
    :return: tuple of low res and high res data
    """
    assert window_size % 2 == 1, "Window size must be odd"
    assert time_range[0] - window_size // 2 >= 1, "Time step out of range"
    assert time_range[1] + window_size // 2 <= 1024, "Time step out of range"
    assert time_range[0] >= 1 and time_range[1] <= 1024, "Time step out of range"

    np.random.seed(seed)
    # download all the data
    tmp_data_dir = root / "tmp"
    all_params_lr, all_params_hr, _ = download_generic(
        total_samples,
        domain_size,
        lr_factor,
        time_range,
        window_size,
        tmp_data_dir,
        token,
    )
    assert len(all_params_lr) == len(all_params_hr), "Length mismatch"

    # split the data
    cur_root = root / name
    cur_root.mkdir(parents=True, exist_ok=True)
    splits_ratios = [("train", train_split), ("val", val_split), ("test", test_split)]

    for split, split_ratio in splits_ratios:
        # split data
        split_dir = cur_root / split
        split_params_lr = all_params_lr[: int(total_samples * split_ratio)]
        split_params_hr = all_params_hr[: int(total_samples * split_ratio)]

        # compress all the data to a zip
        split_paths = [
            p["path"]
            for p in split_params_hr + list(chain.from_iterable(split_params_lr))
        ]
        with zipfile.ZipFile(cur_root / f"{split}.zip", "w") as z:
            for p in split_paths:
                z.write(p, p.name)

        # create metadata
        metadata = []
        for lr, hr in zip(split_params_lr, split_params_hr):
            metadata.append(
                {
                    "time_step": hr["time_step"],
                    "window_size": window_size,
                    "sx": hr["start"][0],
                    "sy": hr["start"][1],
                    "sz": hr["start"][2],
                    "ex": hr["end"][0],
                    "ey": hr["end"][1],
                    "ez": hr["end"][2],
                    "lr_factor": lr_factor,
                    "hr_path": str(split_dir / hr["path"].name),
                    "lr_paths": json.dumps(
                        [str(split_dir / p["path"].name) for p in lr]
                    ),
                }
            )

        metadata_df = pd.DataFrame(metadata)
        metadata_df.to_csv(cur_root / f"metadata_{split}.csv", index=False)


if __name__ == "__main__":
    CLI(make_jhtdb_dataset)