"""#98 pixel proof: locate the FLASHING lamp by temporal variance.

A flashing lamp alternates between two appearances, so across frames of an
otherwise-static cockpit it is the pixels that CHANGE.  Comparing a leaking run
against an undamaged control run localises the flash without anyone having to
guess panel coordinates first.
"""
import glob, sys
import numpy as np
from PIL import Image

# The 2D cockpit panels only -- excludes the 3D viewport so world/particle
# motion cannot be mistaken for a lamp.  (Viewport is ~x 280-1170, y 225-660.)
PANEL_LEFT = (slice(0, 300), slice(0, 330))      # (rows, cols) -- the coolant panel

def frames(prefix, take=40):
    # the last frame is often truncated (the process is killed mid-write), and a
    # corrupt frame must not be mistaken for change -- skip anything unreadable
    fs = sorted(glob.glob("lamp_%s_*.png" % prefix))
    out = []
    for f in reversed(fs):
        if len(out) >= take:
            break
        try:
            out.append(np.asarray(Image.open(f).convert("L"), dtype=np.float32))
        except Exception:
            continue
    if not out:
        raise SystemExit("no readable frames for %s" % prefix)
    return np.stack(out)


def report(prefix):
    a = frames(prefix)
    print("%-6s %d frames, %s" % (prefix, a.shape[0], a.shape[1:]))
    sd = a.std(axis=0)                       # per-pixel temporal std-dev
    panel = sd[PANEL_LEFT]
    print("   coolant-panel std: mean=%.3f  max=%.1f  pixels>10: %d"
          % (panel.mean(), panel.max(), int((panel > 10).sum())))
    if panel.max() > 10:
        ys, xs = np.where(panel > 10)
        print("   hotspot bbox rows %d-%d, cols %d-%d  (centroid %d,%d)"
              % (ys.min(), ys.max(), xs.min(), xs.max(), int(ys.mean()), int(xs.mean())))
    return sd


print("=" * 64)
leak = report("leak")
print()
ctl = report("ctl")

print("\n" + "=" * 64)
pl, pc = leak[PANEL_LEFT], ctl[PANEL_LEFT]
print("VERDICT")
print("  leaking run  : %d panel pixels flashing (std>10)" % int((pl > 10).sum()))
print("  control run  : %d panel pixels flashing (std>10)" % int((pc > 10).sum()))
if (pl > 10).sum() > 0 and (pc > 10).sum() == 0:
    print("  -> a lamp flashes ONLY when a condenser is leaking.  PASS")
elif (pl > 10).sum() == 0:
    print("  -> nothing flashes on the leaking run.  FAIL")
else:
    print("  -> both runs show panel motion; inspect the bboxes above")