from __future__ import annotations

import importlib
from enum import Enum
from pathlib import Path
from typing import Dict, Optional, Type, TypeVar, Union

import torch
import yaml
from ase import Atoms
from ase.calculators.calculator import Calculator, all_changes
from huggingface_hub import PyTorchModelHubMixin
from torch import nn
from typing_extensions import Self

try:
    from mlip_arena.data.collate import collate_fn
except ImportError:
    # Fallback to a dummy function if the import fails
    def collate_fn(batch: list[Atoms], cutoff: float) -> None:
        raise ImportError(
            "collate_fn import failed. Please install the required dependencies."
        )

try:
    from prefect.logging import get_run_logger
    logger = get_run_logger()
except (ImportError, RuntimeError):
    from loguru import logger

T = TypeVar("T", bound="MLIP")



with open(Path(__file__).parent / "registry.yaml", encoding="utf-8") as f:
    REGISTRY = yaml.safe_load(f)

MLIPMap = {}

for model, metadata in REGISTRY.items():
    try:
        module = importlib.import_module(
            f"{__package__}.{metadata['module']}.{metadata['family']}"
        )
        MLIPMap[model] = getattr(module, metadata["class"])
    except (
        ModuleNotFoundError,
        AttributeError,
        ValueError,
        ImportError,
        Exception,
    ) as e:
        logger.warning(e)
        continue
 
MLIPEnum = Enum("MLIPEnum", MLIPMap)
logger.info(f"Successfully loaded models: {list(MLIPEnum.__members__.keys())}")


class MLIP(
    nn.Module,
    PyTorchModelHubMixin,
    tags=["atomistic-simulation", "MLIP"],
):
    def __init__(self, model: nn.Module) -> None:
        super().__init__()
        # https://github.com/pytorch/pytorch/blob/3cbc8c54fd37eb590e2a9206aecf3ab568b3e63c/torch/_dynamo/config.py#L534
        # torch._dynamo.config.compiled_autograd = True
        # self.model = torch.compile(model)
        self.model = model

    def _save_pretrained(self, save_directory: Path) -> None:
        return super()._save_pretrained(save_directory)

    @classmethod
    def from_pretrained(
        cls,
        pretrained_model_name_or_path: str | Path,
        *,
        force_download: bool = False,
        resume_download: bool | None = None,
        proxies: dict | None = None,
        token: str | bool | None = None,
        cache_dir: str | Path | None = None,
        local_files_only: bool = False,
        revision: str | None = None,
        **model_kwargs,
    ) -> Self:
        return super().from_pretrained(
            pretrained_model_name_or_path,
            force_download=force_download,
            resume_download=resume_download,
            proxies=proxies,
            token=token,
            cache_dir=cache_dir,
            local_files_only=local_files_only,
            revision=revision,
            **model_kwargs,
        )

    def forward(self, x):
        return self.model(x)


class MLIPCalculator(MLIP, Calculator):
    name: str
    implemented_properties: list[str] = ["energy", "forces", "stress"]

    def __init__(
        self,
        model: nn.Module,
        device: torch.device | None = None,
        cutoff: float = 6.0,
        # ASE Calculator
        restart=None,
        atoms=None,
        directory=".",
        calculator_kwargs: dict = {},
    ):
        MLIP.__init__(self, model=model)  # Initialize MLIP part
        Calculator.__init__(
            self, restart=restart, atoms=atoms, directory=directory, **calculator_kwargs
        )  # Initialize ASE Calculator part
        # Additional initialization if needed
        # self.name: str = self.__class__.__name__
        from mlip_arena.models.utils import get_freer_device

        self.device = device or get_freer_device()
        self.cutoff = cutoff
        self.model.to(self.device)
        # self.device = device or torch.device(
        #     "cuda" if torch.cuda.is_available() else "cpu"
        # )
        # self.model: MLIP = MLIP.from_pretrained(model_path, map_location=self.device)
        # self.implemented_properties = ["energy", "forces", "stress"]

    # def __getstate__(self):
    #     state = self.__dict__.copy()
    #     state["_modules"]["model"] = state["_modules"]["model"]._orig_mod
    #     return state

    # def __setstate__(self, state):
    #     self.__dict__.update(state)
    #     self.model = torch.compile(state["_modules"]["model"])

    def calculate(
        self,
        atoms: Atoms,
        properties: list[str],
        system_changes: list = all_changes,
    ):
        """Calculate energies and forces for the given Atoms object"""
        super().calculate(atoms, properties, system_changes)

        # TODO: move collate_fn to here in MLIPCalculator
        data = collate_fn([atoms], cutoff=self.cutoff).to(self.device)
        output = self.forward(data)

        # TODO: decollate_fn

        self.results = {}
        if "energy" in properties:
            self.results["energy"] = output["energy"].squeeze().item()
        if "forces" in properties:
            self.results["forces"] = output["forces"].squeeze().cpu().detach().numpy()
        if "stress" in properties:
            self.results["stress"] = output["stress"].squeeze().cpu().detach().numpy()

    # def forward(self, x: Atoms) -> dict[str, torch.Tensor]:
    #     """Implement data conversion, graph creation, and model forward pass

    #     Example implementation:
    #     1. Use `ase.neighborlist.NeighborList` to get neighbor list
    #     2. Create `torch_geometric.data.Data` object and copy the data
    #     3. Pass the `Data` object to the model and return the output

    #     """

    #     raise NotImplementedError