# Ultralytics 🚀 AGPL-3.0 License - https://ultralytics.com/license
"""Monkey patches to update/extend functionality of existing functions."""

import time
from contextlib import contextmanager
from copy import copy
from pathlib import Path
from typing import Any, Dict, List, Optional

import cv2
import numpy as np
import torch

# OpenCV Multilanguage-friendly functions ------------------------------------------------------------------------------
_imshow = cv2.imshow  # copy to avoid recursion errors


def imread(filename: str, flags: int = cv2.IMREAD_COLOR) -> Optional[np.ndarray]:
    """
    Read an image from a file with multilanguage filename support.

    Args:
        filename (str): Path to the file to read.
        flags (int, optional): Flag that can take values of cv2.IMREAD_*. Controls how the image is read.

    Returns:
        (np.ndarray | None): The read image array, or None if reading fails.

    Examples:
        >>> img = imread("path/to/image.jpg")
        >>> img = imread("path/to/image.jpg", cv2.IMREAD_GRAYSCALE)
    """
    file_bytes = np.fromfile(filename, np.uint8)
    if filename.endswith((".tiff", ".tif")):
        success, frames = cv2.imdecodemulti(file_bytes, cv2.IMREAD_UNCHANGED)
        if success:
            # Handle RGB images in tif/tiff format
            return frames[0] if len(frames) == 1 and frames[0].ndim == 3 else np.stack(frames, axis=2)
        return None
    else:
        im = cv2.imdecode(file_bytes, flags)
        return im[..., None] if im is not None and im.ndim == 2 else im  # Always ensure 3 dimensions


def imwrite(filename: str, img: np.ndarray, params: Optional[List[int]] = None) -> bool:
    """
    Write an image to a file with multilanguage filename support.

    Args:
        filename (str): Path to the file to write.
        img (np.ndarray): Image to write.
        params (List[int], optional): Additional parameters for image encoding.

    Returns:
        (bool): True if the file was written successfully, False otherwise.

    Examples:
        >>> import numpy as np
        >>> img = np.zeros((100, 100, 3), dtype=np.uint8)  # Create a black image
        >>> success = imwrite("output.jpg", img)  # Write image to file
        >>> print(success)
        True
    """
    try:
        cv2.imencode(Path(filename).suffix, img, params)[1].tofile(filename)
        return True
    except Exception:
        return False


def imshow(winname: str, mat: np.ndarray) -> None:
    """
    Display an image in the specified window with multilanguage window name support.

    This function is a wrapper around OpenCV's imshow function that displays an image in a named window. It handles
    multilanguage window names by encoding them properly for OpenCV compatibility.

    Args:
        winname (str): Name of the window where the image will be displayed. If a window with this name already
            exists, the image will be displayed in that window.
        mat (np.ndarray): Image to be shown. Should be a valid numpy array representing an image.

    Examples:
        >>> import numpy as np
        >>> img = np.zeros((300, 300, 3), dtype=np.uint8)  # Create a black image
        >>> img[:100, :100] = [255, 0, 0]  # Add a blue square
        >>> imshow("Example Window", img)  # Display the image
    """
    _imshow(winname.encode("unicode_escape").decode(), mat)


# PyTorch functions ----------------------------------------------------------------------------------------------------
_torch_save = torch.save


def torch_load(*args, **kwargs):
    """
    Load a PyTorch model with updated arguments to avoid warnings.

    This function wraps torch.load and adds the 'weights_only' argument for PyTorch 1.13.0+ to prevent warnings.

    Args:
        *args (Any): Variable length argument list to pass to torch.load.
        **kwargs (Any): Arbitrary keyword arguments to pass to torch.load.

    Returns:
        (Any): The loaded PyTorch object.

    Notes:
        For PyTorch versions 2.0 and above, this function automatically sets 'weights_only=False'
        if the argument is not provided, to avoid deprecation warnings.
    """
    from ultralytics.utils.torch_utils import TORCH_1_13

    if TORCH_1_13 and "weights_only" not in kwargs:
        kwargs["weights_only"] = False

    return torch.load(*args, **kwargs)


def torch_save(*args, **kwargs):
    """
    Save PyTorch objects with retry mechanism for robustness.

    This function wraps torch.save with 3 retries and exponential backoff in case of save failures, which can occur
    due to device flushing delays or antivirus scanning.

    Args:
        *args (Any): Positional arguments to pass to torch.save.
        **kwargs (Any): Keyword arguments to pass to torch.save.

    Examples:
        >>> model = torch.nn.Linear(10, 1)
        >>> torch_save(model.state_dict(), "model.pt")
    """
    for i in range(4):  # 3 retries
        try:
            return _torch_save(*args, **kwargs)
        except RuntimeError as e:  # Unable to save, possibly waiting for device to flush or antivirus scan
            if i == 3:
                raise e
            time.sleep((2**i) / 2)  # Exponential backoff: 0.5s, 1.0s, 2.0s


@contextmanager
def arange_patch(args):
    """
    Workaround for ONNX torch.arange incompatibility with FP16.

    https://github.com/pytorch/pytorch/issues/148041.
    """
    if args.dynamic and args.half and args.format == "onnx":
        func = torch.arange

        def arange(*args, dtype=None, **kwargs):
            """Return a 1-D tensor of size with values from the interval and common difference."""
            return func(*args, **kwargs).to(dtype)  # cast to dtype instead of passing dtype

        torch.arange = arange  # patch
        yield
        torch.arange = func  # unpatch
    else:
        yield


@contextmanager
def override_configs(args, overrides: Optional[Dict[str, Any]] = None):
    """
    Context manager to temporarily override configurations in args.

    Args:
        args (IterableSimpleNamespace): Original configuration arguments.
        overrides (Dict[str, Any]): Dictionary of overrides to apply.

    Yields:
        (IterableSimpleNamespace): Configuration arguments with overrides applied.
    """
    if overrides:
        original_args = copy(args)
        for key, value in overrides.items():
            setattr(args, key, value)
        try:
            yield args
        finally:
            args.__dict__.update(original_args.__dict__)
    else:
        yield args
