"""NES monochrome: 256x240 greyscale using the PPU's grey ramp (tone by
dithering).  ``--mono-base`` tints the ramp toward a hue."""
from __future__ import annotations

from ...convert.base import Conversion
from . import _common

WIDTH, HEIGHT = 256, 240
PIXEL_ASPECT = 1.0


def convert(img_rgb, palette_name="nes", dither_mode="floyd",
            intensive=False, base_color=None):
    subs = _common.pick_subpalettes(img_rgb, mono=True, base_color=base_color)
    pal32, nt, chr_rom, idx, err, plab, prgb = _common.encode(
        img_rgb, dither_mode, subs)
    return Conversion(
        mode="mono", width=WIDTH, height=HEIGHT, pixel_aspect=PIXEL_ASPECT,
        index_image=idx, data={"palette": pal32, "nametable": nt, "chr": chr_rom},
        data_addr=0, viewer="nes", preview_rgb=prgb[idx], error=err,
        meta={"palette": "nes", "dither": dither_mode},
    )