"""Writes the synthetic pictures the external vectors are encoded from: planar samples of a
fixed pattern, so the inputs are the same on every machine and hold no captured content.

    python3 -I yuv.py <out> <width> <height> <frames> <layout> <depth> [<shift>]

<layout> is 420, 422, 444 (planes Y, Cb, Cr) or rgb (planes R, G, B). Samples above 8 bits
are two bytes, little-endian. <shift> moves the pattern right by that many columns, the
second view of a stereo pair.
"""

import sys


def main(out, w, h, frames, layout, depth, shift=0):
    w, h, frames, depth, shift = int(w), int(h), int(frames), int(depth), int(shift)
    top = (1 << depth) - 1
    if layout == "rgb":
        planes = [(1, 1)] * 3
    else:
        sub = {"420": (2, 2), "422": (2, 1), "444": (1, 1)}[layout]
        planes = [(1, 1), sub, sub]
    data = bytearray()
    for f in range(frames):
        for p, (sx, sy) in enumerate(planes):
            pw, ph = (w + sx - 1) // sx, (h + sy - 1) // sy
            for y in range(ph):
                for x in range(pw):
                    xs = (x * sx - shift) % w
                    # a diagonal ramp, a checker and a moving bar, per plane
                    v = (xs * 3 + y * sy * 5 + f * 7 + p * 40) * (top // 255 if top > 255 else 1)
                    if ((xs // 8) + (y * sy // 8) + p) % 2:
                        v += top // 6
                    if (xs + f * 4) % w < 6:
                        v = top - v % (top // 4 + 1)
                    v %= top + 1
                    data += bytes([v]) if depth <= 8 else v.to_bytes(2, "little")
    with open(out, "wb") as fh:
        fh.write(data)


if __name__ == "__main__":
    main(*sys.argv[1:])