from PIL import Image
from potrace import Bitmap, POTRACE_TURNPOLICY_MINORITY  # `potracer` library


def file_to_svg(filename: str):
    try:

        image = Image.open(filename)
    except IOError:
        print("Image (%s) could not be loaded." % filename)
        return
    bm = Bitmap(image, blacklevel=0.5)
    # bm.invert()
    plist = bm.trace(
        turdsize=2,
        turnpolicy=POTRACE_TURNPOLICY_MINORITY,
        alphamax=1,
        opticurve=False,
        opttolerance=0.2,
    )
    with open(f"{filename}.svg", "w") as fp:
        fp.write(
            f'''<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="{image.width}" height="{image.height}" viewBox="0 0 {image.width} {image.height}">''')
        parts = []
        for curve in plist:
            fs = curve.start_point
            parts.append(f"M{fs.x},{fs.y}")
            for segment in curve.segments:
                if segment.is_corner:
                    a = segment.c
                    b = segment.end_point
                    parts.append(f"L{a.x},{a.y}L{b.x},{b.y}")
                else:
                    a = segment.c1
                    b = segment.c2
                    c = segment.end_point
                    parts.append(f"C{a.x},{a.y} {b.x},{b.y} {c.x},{c.y}")
            parts.append("z")
        fp.write(f'<path stroke="none" fill="black" fill-rule="evenodd" d="{"".join(parts)}"/>')
        fp.write("</svg>")


if __name__ == '__main__':
    file_to_svg('plan.png')