import importlib
from typing import Callable

import typeguard
from hydra.utils import instantiate
from jaxtyping import Float, jaxtyped
from omegaconf import DictConfig

from pdeinvbench.utils.types import (
    HIGH_RESOLUTION_PDE_SPATIAL_SIZE,
    PDE,
    PDE_SPATIAL_SIZE,
)


@jaxtyped(typechecker=typeguard.typechecked)
def get_function_from_string(string: str) -> Callable:
    """
    Converts a function specified as a string to an actual function object. Used in hydra configs.
    """
    module_name, function_name = string.rsplit(".", 1)
    # Import the module dynamically
    module = importlib.import_module(module_name)
    # Get the function object
    function = getattr(module, function_name)
    return function


def resolve_pde_resolution(cfg: DictConfig) -> None:
    """
    Simple utility method which checks if we are using the high resolution data.
    If we are, it updates the types::PDE_SPATIAL_SIZE dict. Currently only
    works with the inverse setting. Assumes keys cfg:high_resolution[bool] and
    cfg.data.downsample_factor[int] exist.
    """
    assert "high_resolution" in cfg, "No key 'high_resolution' found in hydra config"
    assert (
        "data" in cfg and "downsample_factor" in cfg.data
    ), "No key 'data' or 'data.downsample_factor' found in hydra config"
    high_resolution: bool = cfg.high_resolution
    downsample_factor: int = cfg.data.downsample_factor
    pde: PDE = instantiate(cfg.data.pde)

    if high_resolution:
        assert (
            pde in HIGH_RESOLUTION_PDE_SPATIAL_SIZE
        ), f"Could not find {pde} in high resolution PDE size mapping."

    resolution: list[int] = (
        HIGH_RESOLUTION_PDE_SPATIAL_SIZE[pde]
        if high_resolution
        else PDE_SPATIAL_SIZE[pde]
    )
    if (
        downsample_factor == 0
    ):  # Ensures that dynamic setting works without downsampling
        downsample_factor = 1
    new_resolution: list[float] = [res / downsample_factor for res in resolution]
    # only allow downsampling to an integer factor
    for res in new_resolution:
        assert (
            int(res) == res
        ), f"Downsample factor leads to non-integer resolution {res}"

    new_resolution: list[int] = [int(res) for res in new_resolution]
    PDE_SPATIAL_SIZE[pde] = new_resolution