#!/usr/bin/env python3
"""Rasterise icon.svg into the PNG sizes ui.py loads for the window icon.

Tk 8.6 reads PNG but not SVG, so the icon ships pre-rendered in assets/. The
glyph is laid on a rounded plate in the app's own colours: light on dark keeps
it legible against both a light and a dark dock, which the bare SVG (slate grey
on nothing) is not.

Needs inkscape for the render and Pillow for the downscales. Run it after
editing icon.svg, then ./install_desktop.sh to refresh the dock's copies.
"""
import re
import shutil
import subprocess
import sys
from pathlib import Path

HERE   = Path(__file__).resolve().parent
SRC    = HERE / "icon.svg"
OUT    = HERE / "assets"
SIZES  = (256, 128, 64, 48, 32, 16)

PLATE  = 64        # plate side, in the units the composite is drawn in
GLYPH  = 44        # how much of that side the glyph's longest edge covers
RADIUS = 14        # corner rounding of the plate
BG     = "#2b2b2b"  # ui.BAR
FG     = "#ededed"  # ui.FG


def glyph_box(svg):
    """Bounding box of the drawing, in viewBox units.

    inkscape answers in the file's own pixel units, which are viewBox units
    only when width and viewBox agree — so convert.
    """
    out = subprocess.run(["inkscape", "--query-all", str(svg)],
                         capture_output=True, text=True, check=True).stdout
    line = next(l for l in out.splitlines() if l.startswith("svg"))
    x, y, w, h = (float(v) for v in line.split(",")[1:5])

    text = svg.read_text()
    width = float(re.search(r'\swidth="([\d.]+)"', text).group(1))
    vb_w  = float(re.search(r'viewBox="[\d.\-]+ [\d.\-]+ ([\d.]+)', text).group(1))
    u = vb_w / width
    return x * u, y * u, w * u, h * u


def main():
    if not SRC.is_file():
        sys.exit(f"{SRC.name} not found")
    if not shutil.which("inkscape"):
        sys.exit("inkscape not found — needed to rasterise the SVG")
    try:
        from PIL import Image
    except ImportError:
        sys.exit("Pillow not found — needed to downscale the render")

    d = re.search(r'\sd="([^"]+)"', SRC.read_text()).group(1)
    x, y, w, h = glyph_box(SRC)

    # Scale the glyph to GLYPH along its longest edge, then centre what that
    # leaves. The offsets cancel the bbox origin, which is not at 0,0.
    s  = GLYPH / max(w, h)
    tx = (PLATE - w * s) / 2 - x * s
    ty = (PLATE - h * s) / 2 - y * s

    OUT.mkdir(exist_ok=True)
    composite = OUT / "_composite.svg"
    composite.write_text(
        f'<svg xmlns="http://www.w3.org/2000/svg" width="512" height="512" '
        f'viewBox="0 0 {PLATE} {PLATE}">\n'
        f'  <rect width="{PLATE}" height="{PLATE}" rx="{RADIUS}" ry="{RADIUS}" '
        f'fill="{BG}"/>\n'
        f'  <g transform="translate({tx:.4f} {ty:.4f}) scale({s:.6f})">\n'
        f'    <path fill="{FG}" fill-rule="evenodd" clip-rule="evenodd" '
        f'd="{d}"/>\n'
        f'  </g>\n</svg>\n')

    master = OUT / "_master.png"
    subprocess.run(["inkscape", "--export-type=png",
                    f"--export-filename={master}", "-w", "512", "-h", "512",
                    str(composite)], check=True, capture_output=True)

    img = Image.open(master).convert("RGBA")
    for size in SIZES:
        img.resize((size, size), Image.LANCZOS).save(OUT / f"icon-{size}.png")

    composite.unlink()
    master.unlink()
    print(f"glyph bbox {w:.2f}x{h:.2f} at ({x:.2f}, {y:.2f}) "
          f"-> scale {s:.3f}, offset ({tx:.2f}, {ty:.2f})")
    print("wrote " + ", ".join(f"icon-{s}.png" for s in SIZES) + f" in {OUT}")


if __name__ == "__main__":
    main()