import sys

from PIL import Image


def prepare_image(image, width, ascii_aspect_ratio=0.5):
    """resize and grayscale"""
    original_width, original_height = image.size
    aspect_ratio = original_height / original_width
    height = int(width * aspect_ratio * ascii_aspect_ratio)
    resized_image = image.resize((width, height))
    return resized_image.convert('L')


def convert_to_ascii(image, width):
    """map pixels to chars and compose to width"""
    CHARS = ['#', '&', 'S', '?', '/', '=', '+', ',', '.', ' ']
    prepared_image = prepare_image(image, width)
    step = 255 // (len(CHARS) - 1)

    pixels_to_chars = "".join(CHARS[brightness // step] for brightness in prepared_image.getdata())
    ascii_image = (pixels_to_chars[index: index + width] for index in range(0, len(pixels_to_chars), width))

    return "\n".join(ascii_image)


if __name__ == '__main__':
    """usage: python3 ascii_art.py 512.jpg 120"""
    image_file = sys.argv[1]
    width = int(sys.argv[2])
    img = Image.open(image_file)

    ascii = convert_to_ascii(img, width)
    print(ascii)