"""Draws powerUpShield.png for the fredygames.com build of Chromium B.S.U.

The original icon of the shield, repair and super-shield power-ups is the Tux penguin, which the site
leaves out. This one is a plain heater shield in the same format: 64x64 RGBA with a soft white glow
behind it, like the original, which the game tints with the color of each power-up. The PNG made by
this script is versioned next to it (chromium-bsu/powerUpShield.png) and goes into the build in
place of the original; build-chromium-bsu.sh only copies it.

    artifacts/tools/venv/bin/python make-shield-icon.py powerUpShield.png    # Pillow 12.3.0

Written in 2026 by FredyGames for the fredygames.com build of Chromium B.S.U.; distributed with the
game under the Clarified Artistic License (see COPYING).
"""
import sys

from PIL import Image, ImageChops, ImageDraw, PngImagePlugin

SIZE = 64
SCALE = 8  # drawn at 8x and scaled down, for smooth edges
S = SIZE * SCALE


def shield(inset):
    """Outline of a heater shield (flat top, sides curving to a point), inset by `inset` pixels."""
    left, right, top, bottom = 18 * SCALE + inset, 46 * SCALE - inset, 14 * SCALE + inset, 52 * SCALE - inset
    mid = (left + right) / 2
    points = [(left, top), (right, top)]
    steps = 24
    for i in range(1, steps + 1):  # right side: straight down, then curving to the point
        t = i / steps
        points.append((right - (right - mid) * t ** 2.2, top + (bottom - top) * t))
    for i in range(steps - 1, 0, -1):
        t = i / steps
        points.append((left + (mid - left) * t ** 2.2, top + (bottom - top) * t))
    return points


def gradient(top, bottom):
    """Vertical gradient image from color `top` to color `bottom`."""
    image = Image.new('RGBA', (S, S))
    draw = ImageDraw.Draw(image)
    for y in range(S):
        t = y / (S - 1)
        draw.line([(0, y), (S, y)], fill=tuple(round(a + (b - a) * t) for a, b in zip(top, bottom)))
    return image


def main(path):
    # Glow: white, fading out from the center.
    glow = Image.new('L', (S, S), 0)
    pixels = glow.load()
    for y in range(S):
        for x in range(S):
            r = ((x - S / 2) ** 2 + (y - S / 2) ** 2) ** 0.5 / (S / 2)
            pixels[x, y] = round(255 * max(0.0, 1.0 - r) ** 1.1)
    image = Image.new('RGBA', (S, S), (255, 255, 255, 0))
    image.putalpha(glow)

    # Rim: light steel, then the blue face inside it.
    rim_mask = Image.new('L', (S, S), 0)
    ImageDraw.Draw(rim_mask).polygon(shield(0), fill=255)
    image.paste(gradient((235, 240, 250, 255), (120, 130, 150, 255)), (0, 0), rim_mask)

    face_mask = Image.new('L', (S, S), 0)
    ImageDraw.Draw(face_mask).polygon(shield(3 * SCALE), fill=255)
    image.paste(gradient((90, 150, 255, 255), (20, 40, 140, 255)), (0, 0), face_mask)

    # A raised band down the middle and a soft highlight on the upper left.
    band = Image.new('L', (S, S), 0)
    ImageDraw.Draw(band).rectangle([30 * SCALE, 16 * SCALE, 34 * SCALE, 50 * SCALE], fill=255)
    band = ImageChops.multiply(band, face_mask)
    image.paste(gradient((200, 225, 255, 255), (70, 110, 210, 255)), (0, 0), band)

    shine = Image.new('L', (S, S), 0)
    ImageDraw.Draw(shine).ellipse([20 * SCALE, 16 * SCALE, 30 * SCALE, 31 * SCALE], fill=90)
    shine = ImageChops.multiply(shine, face_mask)
    image.paste(Image.new('RGBA', (S, S), (255, 255, 255, 255)), (0, 0), shine)

    image = image.resize((SIZE, SIZE), Image.LANCZOS)
    info = PngImagePlugin.PngInfo()
    info.add_text('Comment', 'Drawn for the fredygames.com build of Chromium B.S.U. on 2026-10-23 '
                             '(make-shield-icon.py), replacing the original powerUpShield.png (Tux).')
    image.save(path, pnginfo=info, optimize=False)


if __name__ == '__main__':
    main(sys.argv[1])