#!/usr/bin/env python3
"""Convert the generated Hydra silhouette to Fastfetch ASCII using Pillow.

Run from the repository root with Python + Pillow (development only):
    python3 dev/render-logo.py
"""

import argparse
from pathlib import Path

from PIL import Image


ROOT = Path(__file__).resolve().parents[1]
RAMP = ' .:-=+*#%@'  # '$' is reserved for Fastfetch color placeholders.
CAPTION = 'H Y D R A  O S'


def render(source, columns):
    # This is a single-color mark: opacity, not luminance, defines its shape.
    # Threshold near-transparent generation noise before reducing the image.
    with Image.open(source) as image:
        mask = image.convert('RGBA').getchannel('A').point(
            lambda value: 255 if value > 160 else 0)
    bounds = mask.getbbox()
    if bounds is None:
        raise ValueError('The source image has no visible silhouette')
    mask = mask.crop(bounds)
    # A terminal character is approximately twice as tall as it is wide.
    rows = max(1, round(mask.height / mask.width * columns * 0.5))
    pixels = mask.resize((columns, rows), Image.Resampling.LANCZOS)
    lines = []
    for y in range(rows):
        line = ''
        for x in range(columns):
            coverage = pixels.getpixel((x, y)) / 255
            level = min(9, max(0, round((coverage - 0.09) / 0.82 * 9)))
            line += RAMP[level]
        lines.append(line.rstrip())
    return '$1' + '\n'.join(lines) + '\n\n$2' + CAPTION.center(columns).rstrip() + '\n'


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--source', type=Path,
                        default=ROOT / 'assets/branding/hydra-mark.png')
    parser.add_argument('--output', type=Path,
                        default=ROOT / 'image/rootfs/usr/share/hydra/fastfetch.txt')
    parser.add_argument('--columns', type=int, default=44)
    args = parser.parse_args()
    if not len(CAPTION) <= args.columns <= 100:
        parser.error('columns must be between 13 and 100')
    args.output.write_text(render(args.source, args.columns), encoding='ascii')
    print(args.output)


if __name__ == '__main__':
    main()