#!/usr/bin/env python3
# Builds the web UI's logo from the master image, artwork/logo.png (a blue
# and white figure on a transparent background), by tracing it into vector
# paths with potrace:
#
#   internal/web/static/assets/logo.svg  the favicon
#   internal/web/static/assets/logo.js   the same paths for the web UI, which
#                                        draws them inline (brand.js), so the
#                                        logo appears together with the page
#
# and then runs scripts/banner.py to rebuild the README's banner.
#
# Both are a few KB, where the PNG is 650 KB. Needs potrace and ImageMagick
# (convert). Run from the repository root after changing the master:
#
#   python3 scripts/logo.py
import os
import re
import subprocess
import sys
import tempfile

MASTER = "artwork/logo.png"
OUT = "internal/web/static/assets"
BLUE = "#1d5287"  # the master's blue
WHITE = "#fff"
PAD = 6  # pixels of the master around the figure


def run(*args):
    return subprocess.run(args, check=True, capture_output=True, text=True).stdout


def trace(pbm):
    """Traces a bitmap into one SVG path (in the master's pixels, y up)."""
    svg = run("potrace", "-b", "svg", "--flat", "-t", "4", "-a", "1.0", "-O", "0.4", "-u", "1", pbm, "-o", "-")
    return " ".join(re.search(r'<path d="([^"]*)"', svg, re.S).group(1).split())


def main():
    with tempfile.TemporaryDirectory() as tmp:
        base, white = os.path.join(tmp, "base.pbm"), os.path.join(tmp, "white.pbm")
        # The figure's whole shape (opaque pixels), drawn in blue...
        run("convert", MASTER, "-alpha", "extract", "-threshold", "50%", "-negate", base)
        # ...and its white parts on top; the blue lines show between them.
        run("convert", MASTER, "-background", "black", "-alpha", "remove", "-alpha", "off",
            "-colorspace", "gray", "-threshold", "75%", "-negate", white)
        layers = [(BLUE, trace(base)), (WHITE, trace(white))]
        height = int(run("identify", "-format", "%h", MASTER))
        w, h, x, y = map(int, re.match(r"(\d+)x(\d+)\+(\d+)\+(\d+)",
                                       run("convert", MASTER, "-alpha", "extract", "-threshold", "50%", "-format", "%@", "info:")).groups())
    side = max(w, h) + 2 * PAD
    view_box = f"{x + w / 2 - side / 2:g} {y + h / 2 - side / 2:g} {side:g} {side:g}"
    transform = f"translate(0 {height}) scale(1 -1)"

    paths = "".join(f'<path fill="{fill}" d="{d}"/>' for fill, d in layers)
    with open(os.path.join(OUT, "logo.svg"), "w") as f:
        f.write(f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="{view_box}">'
                f'<!-- Generated by scripts/logo.py from {MASTER}. -->'
                f'<g transform="{transform}">{paths}</g></svg>\n')
    with open(os.path.join(OUT, "logo.js"), "w") as f:
        f.write(f"// The Jarl logo, traced from {MASTER} by scripts/logo.py; don't edit.\n"
                f"// brand.js draws it; logo.svg holds the same paths.\n"
                f'export const viewBox = "{view_box}";\n'
                f'export const transform = "{transform}";\n'
                "export const layers = [\n"
                + "".join(f'  ["{fill}", "{d}"],\n' for fill, d in layers)
                + "];\n")
    for name in ("logo.svg", "logo.js"):
        print(f"{OUT}/{name}: {os.path.getsize(os.path.join(OUT, name))} bytes", flush=True)
    subprocess.run([sys.executable, "scripts/banner.py"], check=True)


if __name__ == "__main__":
    sys.exit(main())