"""For decoding and loading .ibw AFM file format into Python Numpy arrays."""

import errno
import os
from pathlib import Path

import numpy as np
from igor2 import binarywave

from AFMReader.logging import logger

logger.enable(__package__)


def _ibw_pixel_to_nm_scaling(scan: dict) -> float:
    """
    Extract pixel to nm scaling from the IBW image metadata.

    Parameters
    ----------
    scan : dict
        The loaded binary wave object.

    Returns
    -------
    float
        A value corresponding to the real length of a single pixel.
    """
    # Get metadata
    notes = {}
    for line in str(scan["wave"]["note"]).split("\\r"):
        if line.count(":"):
            key, val = line.split(":", 1)
            notes[key] = val.strip()
    # Has potential for non-square pixels but not yet implemented
    return (
        float(notes["SlowScanSize"]) / scan["wave"]["wData"].shape[0] * 1e9,  # as in m
        float(notes["FastScanSize"]) / scan["wave"]["wData"].shape[1] * 1e9,  # as in m
    )[0]


def load_ibw(file_path: Path | str, channel: str) -> tuple[np.ndarray, float]:
    """
    Load image from Asylum Research (Igor) .ibw files.

    Parameters
    ----------
    file_path : Path | str
        Path to the .ibw file.
    channel : str
        The channel to extract from the .ibw file.

    Returns
    -------
    tuple[np.ndarray, float]
        A tuple containing the image and its pixel to nanometre scaling value.

    Raises
    ------
    FileNotFoundError
        If the file is not found.
    ValueError
        If the channel is not found in the .ibw file.

    Examples
    --------
    Load the image and pixel to nanometre scaling factor - 'HeightTracee' is the default channel name (the extra 'e' is
    not a typo!).

    >>> from AFMReader.ibw import load_ibw
    >>> image, pixel_to_nanometre_scaling_factor = load_ibw(file_path="./my_ibw_file.ibw", channel="HeightTracee")
    """
    logger.info(f"Loading image from : {file_path}")
    file_path = Path(file_path)
    filename = file_path.stem
    # Check the file exists and raise an error if not
    if not file_path.is_file():
        logger.error(f"[{filename}] File not found : {file_path}")
        raise FileNotFoundError(errno.ENOENT, os.strerror(errno.ENOENT), file_path)
    try:
        scan = binarywave.load(file_path)
        logger.info(f"[{filename}] : Loaded image from : {file_path}")
        labels = []
        for label_list in scan["wave"]["labels"]:
            for label in label_list:
                if label:
                    labels.append(label.decode())
        channel_idx = labels.index(channel)
        image = scan["wave"]["wData"][:, :, channel_idx].T * 1e9  # Looks to be in m
        image = np.flipud(image)
        logger.info(f"[{filename}] : Extracted channel {channel}")
    except FileNotFoundError:
        logger.error(f"[{filename}] File not found : {file_path}")
        raise
    except ValueError as e:
        logger.error(f"[{filename}] : '{channel}' not in {file_path.suffix} channel list: {labels}")
        raise ValueError(f"'{channel}' not in {file_path.suffix} channel list: {labels}") from e
    except Exception as e:
        logger.error(f"[{filename}] : {e}")
        raise e

    logger.info(f"[{filename}] : Extracted image.")
    return (image, _ibw_pixel_to_nm_scaling(scan))