#!/usr/bin/env python3
"""Render captured VDB palettes (VDB_PALDUMP <prefix>N.rgb) as swatch images.

Each .rgb is 256 RGB triplets (768 bytes) -- one of the VDB's three display
palette groups (secondary / aux1 / aux2). For each, emit:
  <prefix>N.png  -- a 16x16 grid of the 256 colors + a 256-wide linear ramp.

Usage: render_vdb_palettes.py <prefix>   (e.g. .../scratchpad/vdbpal)
"""
import sys

from PIL import Image, ImageDraw, ImageFont

NAMES = {0: "secondary (dynamic)", 1: "aux 1", 2: "aux 2"}


def render_one(path, out, title):
    data = open(path, "rb").read()
    if len(data) < 768:
        data = data + b"\x00" * (768 - len(data))
    cols = [(data[i * 3], data[i * 3 + 1], data[i * 3 + 2]) for i in range(256)]

    cell, grid = 28, 16
    gw = cell * grid
    ramp_h = 40
    pad, top = 12, 34
    W = gw + pad * 2
    H = top + gw + 10 + ramp_h + pad
    img = Image.new("RGB", (W, H), (24, 24, 28))
    d = ImageDraw.Draw(img)
    try:
        font = ImageFont.truetype("consola.ttf", 16)
    except Exception:
        font = ImageFont.load_default()
    d.text((pad, 8), title, fill=(230, 230, 235), font=font)

    # 16x16 swatch grid (index 0 top-left, row-major)
    for i, c in enumerate(cols):
        x = pad + (i % grid) * cell
        y = top + (i // grid) * cell
        d.rectangle([x, y, x + cell - 1, y + cell - 1], fill=c)
    # linear ramp strip below
    ry = top + gw + 10
    for i, c in enumerate(cols):
        x0 = pad + i * (gw / 256.0)
        x1 = pad + (i + 1) * (gw / 256.0)
        d.rectangle([x0, ry, x1, ry + ramp_h], fill=c)
    d.rectangle([pad, ry, pad + gw, ry + ramp_h], outline=(80, 80, 88))
    img.save(out)
    # quick stats
    grays = sum(1 for r, g, b in cols if abs(r - g) < 6 and abs(g - b) < 6)
    print(f"{out}: {grays}/256 grayscale-ish entries")


def main():
    prefix = sys.argv[1]
    for g in (0, 1, 2):
        p = f"{prefix}{g}.rgb"
        try:
            render_one(p, f"{prefix}{g}.png",
                       f"VDB palette {g} - {NAMES.get(g, '')}")
        except FileNotFoundError:
            print(f"(no {p})")


if __name__ == "__main__":
    main()