import os
import numpy as np

im_ext = [
    ".fits",
    ".tiff",
    ".tif",
    ".hdf",
    ".h4",
    ".hdf4",
    ".he2",
    "h5",
    ".hdf5",
    ".he5",
]


def get_sorted_list_images(folder=""):
    """return the list of images sorted that have the correct format

    Parameters:
       folder: string of the path containing the images

    Return:
       sorted list of only images that can be read by program
    """
    filenames = [
        name for name in os.listdir(folder) if name.lower().endswith(tuple(im_ext))
    ]
    filenames.sort()
    return filenames


def average_df(df=[]):
    """if more than 1 DF have been provided, we need to average them"""
    mean_average = np.mean(df, axis=0)
    return mean_average
