"""C128 VDC high-resolution greyscale / black-and-white (640x200).

MAME's 8563 has no true linear bitmap renderer (its R25-bit7 "bitmap" path only
emits one bit per 8-pixel cell), so genuine 640x200 detail has to come through
the character/font path -- exactly as the `hicolor` mode does.  This mode reuses
that machinery restricted to the VDC's four greys (black, dark grey, light grey,
white): each 8x8 cell picks the grey that best matches it over a global grey
background and dithers to a 1bpp glyph, giving smooth multi-level greyscale at
full resolution.  `--mono-base` swaps the grey ramp for a black->colour->white
ramp to tint the result.
"""
from __future__ import annotations

from . import hicolor

WIDTH, HEIGHT = hicolor.WIDTH, hicolor.HEIGHT
PIXEL_ASPECT = hicolor.PIXEL_ASPECT

GREYS = [0, 1, 14, 15]              # VDC black, dark grey, light grey, white


def convert(img_rgb, palette_name="vdc", dither_mode="floyd",
            intensive=False, base_color=None):
    if base_color in range(1, 16):
        inks = sorted({0, int(base_color), 15})            # black -> tint -> white
    else:
        inks = GREYS
    return hicolor.build(img_rgb, dither_mode, inks=inks, bg_list=inks,
                         mode_name="mono")