import statistics
import sys
from dataclasses import dataclass
from typing import List, Union

import torch
from numpy.typing import NDArray

from type_aliases import DEVICE_TYPE, ENCODER_DEVICE_TYPE, NumSentencesType, EmbeddingSlicesType


def get_gpu(gpu: DEVICE_TYPE) -> ENCODER_DEVICE_TYPE:
    """
        Determine the correct GPU device based on the provided input. In the following, output 0 means CUDA device 0.

        Args:
            gpu (Union[bool, str, int, List[Union[str, int]]]): Input specifying the GPU device(s):
                - bool: If True, returns 0 if CUDA is available, otherwise returns "cpu".
                - str: Can be "cpu", "gpu", or "cuda" (case-insensitive). Returns 0 if CUDA is available
                  and the input is not "cpu", otherwise returns "cpu".
                - int: Should be a valid GPU index. Returns the index if CUDA is available and valid,
                  otherwise returns "cpu".
                - List[Union[str, int]]: List containing combinations of the str/int. Processes each
                  element and returns a list of corresponding results.

        Returns:
            Union[str, int, List[Union[str, int]]]: Depending on the input type:
                - str: Returns "cpu" if no GPU is available or the input is "cpu".
                - int: Returns the GPU index if valid and CUDA is available.
                - List[Union[str, int]]: Returns a list of strings and/or integers based on the input list.

        Raises:
            ValueError: If the input gpu type is not recognized or invalid.
            ValueError: If a string input is not one of ["cpu", "gpu", "cuda"].
            ValueError: If an integer input is outside the valid range of GPU indices.

        Notes:
            - This function checks CUDA availability using torch.cuda.is_available() and counts
              available GPUs using torch.cuda.device_count().
            - Case insensitivity is maintained for string inputs ("cpu", "gpu", "cuda").
            - The function ensures robust error handling for invalid input types or out-of-range indices.
        """

    # Ensure gpu index is within the range of total available gpus
    gpu_available = torch.cuda.is_available()
    gpu_count = torch.cuda.device_count()
    correct_strs = ["cpu", "gpu", "cuda"]

    def _get_single_device(gpu_item):
        if isinstance(gpu_item, bool):
            return 0 if gpu_item and gpu_available else "cpu"
        elif isinstance(gpu_item, str):
            if gpu_item.lower() not in correct_strs:
                raise ValueError(f"Wrong gpu type: {gpu_item}. Should be one of {correct_strs}")
            return 0 if (gpu_item.lower() != "cpu") and gpu_available else "cpu"
        elif isinstance(gpu_item, int):
            if gpu_item >= gpu_count:
                raise ValueError(
                    f"There are {gpu_count} GPUs available. Provide a valid GPU index. You provided: {gpu_item}"
                )
            return gpu_item if gpu_available else "cpu"
        else:
            raise ValueError(f"Invalid gpu type: {type(gpu_item)}. Must be bool, str, or int.")

    if isinstance(gpu, list):
        seen_indices = set()
        result = []
        for item in gpu:
            device = _get_single_device(item)
            if isinstance(device, int):
                if device not in seen_indices:
                    seen_indices.add(device)
                    result.append(device)
            else:
                result.append(device)
        return result
    else:
        return _get_single_device(gpu)


def slice_embeddings(embeddings: NDArray, num_sentences: NumSentencesType) -> EmbeddingSlicesType:
    def _slice_embeddings(s_idx: int, n_sentences: List[int]):
        _result = []
        for count in n_sentences:
            _result.append(embeddings[s_idx:s_idx + count])
            s_idx += count
        return _result, s_idx

    if isinstance(num_sentences, list) and all(isinstance(item, int) for item in num_sentences):
        result, _ = _slice_embeddings(0, num_sentences)
        return result
    elif isinstance(num_sentences, list) and all(
            isinstance(sublist, list) and all(
                isinstance(item, int) for item in sublist
            )
            for sublist in num_sentences
    ):
        nested_result = []
        start_idx = 0
        for nested_num_sentences in num_sentences:
            embedding_slice, start_idx = _slice_embeddings(start_idx, nested_num_sentences)
            nested_result.append(embedding_slice)

        return nested_result
    else:
        raise TypeError(f"Incorrect Type for {num_sentences=}")


def is_nested_list_of_type(lst_obj, element_type, depth: int) -> bool:
    if depth == 0:
        return isinstance(lst_obj, element_type)
    elif depth > 0:
        return isinstance(lst_obj, list) and all(is_nested_list_of_type(item, element_type, depth - 1) for item in lst_obj)
    else:
        raise ValueError("Depth can't be negative")


def flatten_list(nested_list: list) -> list:
    """
    Recursively flattens a nested list of any depth.

    Parameters:
        nested_list (list): The nested list to flatten.

    Returns:
        list: A flat list containing all the elements of the nested list.
    """
    flat_list = []
    for item in nested_list:
        if isinstance(item, list):
            flat_list.extend(flatten_list(item))
        else:
            flat_list.append(item)
    return flat_list


def compute_f1(p: float, r: float, eps=sys.float_info.epsilon) -> float:
    """
    Computes F1 value
    :param p: Precision Value
    :param r: Recall Value
    :param eps: Epsilon Value
    :return:
    """
    f1 = 2 * p * r / (p + r + eps)
    return f1


@dataclass
class Scores:
    precision: float
    recall: List[float]

    def __post_init__(self):
        self.f1: float = compute_f1(self.precision, statistics.fmean(self.recall))