#!/usr/bin/env python3
"""Draw desktop/icon-source.png — the 1024² master the icon set is cut from.

The wiki's own mark is the ∑ in the sidebar (AppHeader.vue's .logo-mark) over
the dark reading surface, so the app icon is that: the sigma, in the accent the
wiki wears by default, on the dark navy of its dark theme.

    python3 desktop/make-icon.py       # writes desktop/icon-source.png
    npm run desktop:icons              # cuts src-tauri/icons/ from it

Requires Pillow (pip install pillow). Nothing else in the project uses it —
this is build tooling, not app code.
"""

from pathlib import Path

from PIL import Image, ImageDraw, ImageFont

SIZE = 1024
PAD = 64  # the margin macOS wants round an app icon; harmless elsewhere
RADIUS = 200
TOP = (16, 21, 44)  # the navy a touch above --bg, so the square reads as an object
BOTTOM = (6, 8, 14)  # ... down to just under it
ACCENT = (124, 140, 255)  # --accent, dark theme (#7c8cff)
MARK = "\u2211"  # ∑ — the wiki's mark

FONTS = [
    "/usr/share/fonts/truetype/dejavu/DejaVuSerif-Bold.ttf",
    "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
    "/usr/share/fonts/truetype/liberation/LiberationSerif-Bold.ttf",
]

OUT = Path(__file__).resolve().parent / "icon-source.png"


def load_font(size: int) -> ImageFont.FreeTypeFont:
    """The first system font that actually carries a sigma."""
    for path in FONTS:
        try:
            font = ImageFont.truetype(path, size)
        except OSError:
            continue
        if font.getbbox(MARK)[2] > 0:
            return font
    raise SystemExit(f"no font with a {MARK} found — look for one of: {', '.join(FONTS)}")


def main() -> None:
    # vertical gradient, then clipped to a rounded square
    gradient = Image.new("RGB", (1, SIZE))
    for y in range(SIZE):
        t = y / (SIZE - 1)
        gradient.putpixel((0, y), tuple(round(a + (b - a) * t) for a, b in zip(TOP, BOTTOM)))
    gradient = gradient.resize((SIZE, SIZE))

    mask = Image.new("L", (SIZE, SIZE), 0)
    ImageDraw.Draw(mask).rounded_rectangle(
        [PAD, PAD, SIZE - PAD, SIZE - PAD], radius=RADIUS, fill=255
    )

    icon = Image.new("RGBA", (SIZE, SIZE), (0, 0, 0, 0))
    icon.paste(gradient, (0, 0), mask)

    draw = ImageDraw.Draw(icon)
    # a hairline of accent light along the edge, so the dark square does not
    # vanish into a dark taskbar
    draw.rounded_rectangle(
        [PAD, PAD, SIZE - PAD, SIZE - PAD], radius=RADIUS, outline=(124, 140, 255, 56), width=3
    )

    font = load_font(600)
    left, top, right, bottom = draw.textbbox((0, 0), MARK, font=font)
    w, h = right - left, bottom - top
    # centred on the box the glyph is drawn in, not on its typographic cell:
    # an ascent-based centre would sit the sigma high
    draw.text(
        ((SIZE - w) / 2 - left, (SIZE - h) / 2 - top),
        MARK,
        font=font,
        fill=ACCENT + (255,),
    )

    icon.save(OUT)
    print(f"wrote {OUT}")


if __name__ == "__main__":
    main()