#!/usr/bin/env python3
"""Global camera motion + cut map for a short vertical clip (NumPy + ffmpeg only).

usage: python3 camera_motion.py clip.mp4 [more.mp4 ...] [--fps 12] [--csv out.csv]
"""
import argparse, csv, subprocess, sys
import numpy as np

W, H = 144, 256  # analysis size (9:16); small is enough for global motion

def frames(path, fps):
    cmd = ["ffmpeg", "-v", "error", "-i", path, "-vf",
           f"fps={fps},scale={W}:{H}:force_original_aspect_ratio=disable,format=gray",
           "-f", "rawvideo", "-"]
    raw = subprocess.run(cmd, capture_output=True, check=True).stdout
    return np.frombuffer(raw, np.uint8).reshape(-1, H, W).astype(np.float32)

WIN = np.outer(np.hanning(H), np.hanning(W)).astype(np.float32)

def phase_corr(a, b):
    """Return (dx, dy, peak) so that b is roughly a shifted by (dx, dy)."""
    A = np.fft.fft2((a - a.mean()) * WIN)
    B = np.fft.fft2((b - b.mean()) * WIN)
    R = np.conj(A) * B
    R /= np.abs(R) + 1e-9
    r = np.fft.ifft2(R).real
    y, x = np.unravel_index(np.argmax(r), r.shape)
    if y > H // 2: y -= H
    if x > W // 2: x -= W
    return float(x), float(y), float(r.max())

def analyse(path, fps, cut_peak=0.06):
    f = frames(path, fps)
    rows = []
    for i in range(1, len(f)):
        dx, dy, peak = phase_corr(f[i - 1], f[i])
        rows.append({"t": round(i / fps, 3), "dx": dx, "dy": dy,
                     "peak": round(peak, 3), "cut": peak < cut_peak})
    return rows

def summary(rows):
    cuts = [r["t"] for r in rows if r["cut"]]
    # merge cut flags closer than 0.25 s (one cut can flag two pairs)
    merged = []
    for t in cuts:
        if not merged or t - merged[-1] > 0.25:
            merged.append(t)
    still = [r for r in rows if not r["cut"]]
    pan = sum(abs(r["dx"]) for r in still)
    tilt = sum(abs(r["dy"]) for r in still)
    moving = sum(1 for r in still if abs(r["dx"]) + abs(r["dy"]) >= 1) / max(len(still), 1)
    return merged, pan, tilt, moving

if __name__ == "__main__":
    ap = argparse.ArgumentParser()
    ap.add_argument("clips", nargs="+")
    ap.add_argument("--fps", type=float, default=12)
    ap.add_argument("--csv")
    a = ap.parse_args()
    out = []
    print(f"{'clip':<14}{'cuts (s)':<34}{'pan px':>8}{'tilt px':>8}{'moving':>8}")
    for c in a.clips:
        rows = analyse(c, a.fps)
        cuts, pan, tilt, moving = summary(rows)
        name = c.rsplit("/", 1)[-1][:12]
        print(f"{name:<14}{', '.join(f'{t:.2f}' for t in cuts):<34}{pan:>8.0f}{tilt:>8.0f}{moving:>8.0%}")
        out += [{"clip": name, **r} for r in rows]
    if a.csv:
        with open(a.csv, "w", newline="") as fh:
            w = csv.DictWriter(fh, fieldnames=list(out[0]))
            w.writeheader(); w.writerows(out)