import logging
from pathlib import Path
import numpy as np
import torch
import torchvision.transforms as tfm
import os
import contextlib
from yacs.config import CfgNode as CN
import sys
from typing import Union, Optional, Dict, List, Tuple, Any

logger = logging.getLogger()
logger.setLevel(31)  # Avoid printing useless low-level logs


def get_image_pairs_paths(inputs: Union[List[Path], List[str]]) -> List[Tuple[Path, Path]]:
    """Get pairs of image paths from various input formats.

    Args:
        inputs: List of input paths (1 or 2 items) or single directory/file

    Returns:
        List of tuples containing image path pairs
    """
    if len(inputs) > 2:
        raise ValueError(f"--input should be one or two paths, not {len(inputs)} paths like {inputs}")

    if len(inputs) == 2:
        # --input is two paths of images
        if not Path(inputs[0]).is_file() or not Path(inputs[1]).is_file():
            raise ValueError(f"If --input is two paths, it should be two images, not {inputs}")
        return [(Path(inputs[0]), Path(inputs[1]))]

    assert len(inputs) == 1
    inputs = Path(inputs[0])

    if not inputs.exists():
        raise ValueError(f"{inputs} does not exist")

    if inputs.is_file():
        # --input is a file with pairs of images paths
        with open(inputs) as file:
            lines = file.read().splitlines()
        pairs_of_paths = [line.strip().split(" ") for line in lines]
        for pair in pairs_of_paths:
            if len(pair) != 2:
                raise ValueError(f"{pair} should be a pair of paths")
        return [(Path(path0.strip()), Path(path1.strip())) for path0, path1 in pairs_of_paths]
    else:
        inner_files = sorted(inputs.glob("*"))
        if len(inner_files) == 2 and inner_files[0].is_file() and inner_files[1].is_file():
            # --input is a dir with a pair of images
            return [(inner_files[0], inner_files[1])]
        else:
            # --input is a dir of subdirs, where each subdir has a pair of images
            pairs_of_paths = [sorted(pair_dir.glob("*")) for pair_dir in inner_files]
            for pair in pairs_of_paths:
                if len(pair) != 2:
                    raise ValueError(f"{pair} should be a pair of paths")
            return [(pair[0], pair[1]) for pair in pairs_of_paths]


def to_numpy(x: Union[torch.Tensor, np.ndarray, Dict, List]) -> Union[np.ndarray, Dict, List]:
    """Convert item or container of items to numpy.

    Args:
        x: Input to convert (Tensor, ndarray, dict or list)

    Returns:
        Numpy array or container with numpy arrays
    """
    if isinstance(x, list):
        return [to_numpy(i) for i in x]
    if isinstance(x, dict):
        return {k: to_numpy(v) for k, v in x.items()}
    if isinstance(x, torch.Tensor):
        return x.cpu().numpy()
    return x


def to_tensor(x: Union[np.ndarray, torch.Tensor], device: Optional[str] = None) -> torch.Tensor:
    """Convert to tensor and place on device.

    Args:
        x: Item to convert to tensor
        device: Device to place tensor on

    Returns:
        Tensor with data from x on specified device
    """
    if not isinstance(x, torch.Tensor):
        x = torch.from_numpy(x)
    return x.to(device) if device is not None else x


def to_normalized_coords(pts: Union[np.ndarray, torch.Tensor], height: int, width: int) -> np.ndarray:
    """Normalize keypoint coordinates from pixel space to [0,1].

    Args:
        pts: Array of keypoints in shape (N, 2) (x,y order)
        height: Image height
        width: Image width

    Returns:
        Keypoints in normalized [0,1] coordinates
    """
    assert pts.shape[-1] == 2, f"Input should be shape (N, 2), got {pts.shape}"
    pts = to_numpy(pts).astype(float)
    pts[:, 0] /= width
    pts[:, 1] /= height
    return pts


def to_px_coords(pts: Union[np.ndarray, torch.Tensor], height: int, width: int) -> np.ndarray:
    """Unnormalize keypoint coordinates from [0,1] to pixel space.

    Args:
        pts: Array of keypoints in shape (N, 2) (x,y order)
        height: Image height
        width: Image width

    Returns:
        Keypoints in pixel coordinates
    """
    assert pts.shape[-1] == 2, f"Input should be shape (N, 2), got {pts.shape}"
    pts = to_numpy(pts)
    pts[:, 0] *= width
    pts[:, 1] *= height
    return pts


def resize_to_divisible(img: torch.Tensor, divisible_by: int = 14) -> torch.Tensor:
    """Resize to be divisible by a factor (useful for ViT models).

    Args:
        img: Image tensor in (*, H, W) order
        divisible_by: Factor to ensure divisibility

    Returns:
        Image tensor with divisible shape
    """
    h, w = img.shape[-2:]
    divisible_h = round(h / divisible_by) * divisible_by
    divisible_w = round(w / divisible_by) * divisible_by
    return tfm.functional.resize(img, [divisible_h, divisible_w], antialias=True)


def supress_stdout(func):
    """Decorator to suppress stdout from a function."""
    def wrapper(*args, **kwargs):
        with open(os.devnull, "w") as devnull:
            with contextlib.redirect_stdout(devnull):
                return func(*args, **kwargs)
    return wrapper


def lower_config(yacs_cfg: Union[CN, Dict]) -> Dict:
    """Convert YACS config to lowercase dictionary."""
    if not isinstance(yacs_cfg, CN):
        return yacs_cfg
    return {k.lower(): lower_config(v) for k, v in yacs_cfg.items()}


def load_module(module_name: str, module_path: Union[Path, str]) -> None:
    """Load module from path into interpreter with given namespace.

    Args:
        module_name: Module name for importing
        module_path: Path to module (usually __init__.py)
    """
    import importlib.util
    module_path = str(module_path)
    spec = importlib.util.spec_from_file_location(module_name, module_path)
    module = importlib.util.module_from_spec(spec)
    sys.modules[module_name] = module
    spec.loader.exec_module(module)


def add_to_path(path: Union[str, Path], insert: Optional[int] = None) -> None:
    """Add path to sys.path at specified position."""
    path = str(path)
    if path in sys.path:
        sys.path.remove(path)
    if insert is None:
        sys.path.append(path)
    else:
        sys.path.insert(insert, path)


def get_default_device() -> str:
    """Get default device (cuda/mps/cpu) based on availability."""
    if sys.platform == "darwin" and torch.backends.mps.is_available():
        return "mps"
    return "cuda" if torch.cuda.is_available() else "cpu"