dmsn

#!/usr/bin/env python3
# enter an image and percentage to scale by and print the result
# requires pillow

import sys
from PIL import Image, UnidentifiedImageError


def main() -> int:
    """perform the main operations"""
    if len(sys.argv) != 3 or ("-h", "--help") in sys.argv:
        usage()

    image: str = sys.argv[1]
    try:
        percent: float = float(sys.argv[2].strip("%"))
    except ValueError:
        print(f"Invalid value for percent: {sys.argv[2]}. Value must be a number.\n")
        usage(1)

    dimensions: dict = get_dimensions(image)
    dimensions = resize_dimensions(dimensions, percent * 0.01)
    print(f"{dimensions['width']} x {dimensions['height']}")

    return 0


def get_dimensions(image: str) -> dict:
    """get the dimensions of {image}"""
    try:
        img: Image = Image.open(image)
    except FileNotFoundError as err:
        print(err)
        sys.exit(1)
    except UnidentifiedImageError:
        print(f"{image} is not an image.")
        sys.exit(1)
    width, height = img.size
    return {"width": width, "height": height}


def resize_dimensions(dimensions, scaling) -> dict:
    """return the new dimensions of an image"""
    for dim in dimensions.keys():
        dimensions[dim] *= scaling
    return dimensions


def usage(exit_code=0):
    """print usage information"""
    print(
        """
usage: dmsn [-h] image percent

positional arguments:
    image  path to an image to get the dimensions of (string)

optional arguments:
    percent     percentage to scale the image by (number)
    -h, --help  show this help message and exit
""".strip()
    )
    sys.exit(exit_code)


if __name__ == "__main__":
    main()