# Measuring a frame: the shares of the surfaces, the borders of the panels, the heights of the
# strips, the baselines of the text. The tool exists for the sake of the norm "work by measurement
# and not by eye" (FRONTEND_PLAN.md §5): every session that touches scale and gaps is bound to bring
# numbers rather than an impression.
#
#   .tooling/py/bin/python scripts/measure.py references/fleet.png .shots/showcase.png
#
# Both frames are brought to CSS pixels by their own scale (the --scale argument, 2 by default —
# both the reference and our shot were taken at deviceScaleFactor 2).
#
# Pillow is pinned in scripts/requirements.txt — the procedure of installing it is there too. The
# system python on the stand comes without it, hence the venv in .tooling/py (it does not travel
# into git).

import sys
from collections import Counter

from PIL import Image


def surfaces(image, top=8):
    counts = Counter(image.getdata())
    total = sum(counts.values())
    return [
        ('#%02x%02x%02x' % color, round(100 * n / total, 2)) for color, n in counts.most_common(top)
    ]


def runs(values, minimum=2):
    """Runs of one and the same value in a row: (value, start, length)."""
    out = []
    start = 0
    for index in range(1, len(values) + 1):
        if index == len(values) or values[index] != values[start]:
            if index - start >= minimum:
                out.append((values[start], start, index - start))
            start = index
    return out


def column_profile(image, y):
    """The colours along a horizontal cut — this is how panel borders and gaps become visible."""
    return [image.getpixel((x, y)) for x in range(image.width)]


def row_profile(image, x):
    return [image.getpixel((x, y)) for y in range(image.height)]


def report(path, scale):
    image = Image.open(path).convert('RGB')
    print(f'\n=== {path} — {image.width}x{image.height} phys, {image.width // scale}x{image.height // scale} CSS ===')
    print('surfaces (share of the frame):')
    for color, share in surfaces(image):
        print(f'  {color}  {share:5.2f}%')

    middle = image.height // 2
    # The probe is taken at the centre of the top strip and not in a corner: on the reference the
    # corners of the macOS window are rounded, and in the corner lies the black ground of the
    # desktop, not the ground of the shell.
    shell = image.getpixel((image.width // 2, 2 * scale))
    print('\nground of the shell (top strip): #%02x%02x%02x' % shell)

    # A horizontal cut through the middle: the runs of the shell's ground = the gaps between panels.
    strip = column_profile(image, middle)
    gaps = [(start, length) for color, start, length in runs(strip) if color == shell]
    print('gaps of the ground horizontally (CSS: start, width):')
    for start, length in gaps:
        print(f'  x={start / scale:7.1f}  w={length / scale:5.1f}')

    # A vertical cut down the left edge of the panel: the top strip and the status strip.
    x = gaps[0][0] + gaps[0][1] + 4 if gaps else 20
    column = row_profile(image, x)
    bands = [(start, length) for color, start, length in runs(column) if color == shell]
    print(f'bands of the ground vertically at x={x / scale:.1f} (CSS: start, height):')
    for start, length in bands:
        print(f'  y={start / scale:7.1f}  h={length / scale:5.1f}')


if __name__ == '__main__':
    args = [a for a in sys.argv[1:] if not a.startswith('--')]
    scale = 2
    for a in sys.argv[1:]:
        if a.startswith('--scale='):
            scale = int(a.split('=')[1])
    for path in args:
        report(path, scale)