#!/usr/bin/env python3
"""Capture the RCT-facing UVC webcam and score lower-half video corruption."""

from __future__ import annotations

import argparse
import collections
import json
import os
import pathlib
import shlex
import shutil
import subprocess
import sys
import time
from typing import Any

DEFAULT_DEVICE_LABEL = "Lesavka Composite"


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description=(
            "Long-running Lesavka RCT UVC artifact probe. It captures decoded "
            "grayscale frames from the host-side UVC device, flags lower-half "
            "slabs/tears, and writes JSON/PGM artifacts for review."
        )
    )
    parser.add_argument("--host", default="", help="optional SSH host, e.g. tethys")
    parser.add_argument("--source", choices=["device", "x11"], default="device")
    parser.add_argument("--device", default="auto", help="video device or auto")
    parser.add_argument("--display", default=":0", help="X11 display for --source x11")
    parser.add_argument("--crop", default="", help="X11 crop as x,y,width,height for --source x11")
    parser.add_argument("--device-label", default=DEFAULT_DEVICE_LABEL)
    parser.add_argument("--width", type=int, default=1280)
    parser.add_argument("--height", type=int, default=720)
    parser.add_argument("--fps", type=int, default=30)
    parser.add_argument("--duration", type=float, default=180.0)
    parser.add_argument("--artifact-dir", default="")
    parser.add_argument("--remote-artifact-dir", default="")
    parser.add_argument("--x-step", type=int, default=8)
    parser.add_argument("--y-step", type=int, default=4)
    parser.add_argument("--bands", type=int, default=24)
    parser.add_argument("--flat-var", type=float, default=18.0)
    parser.add_argument("--delta-threshold", type=float, default=24.0)
    parser.add_argument("--jump-threshold", type=float, default=34.0)
    parser.add_argument("--max-suspicious-artifacts", type=int, default=40)
    parser.add_argument("--progress-every", type=int, default=150)
    parser.add_argument("--self-test", action="store_true")
    return parser.parse_args()


def timestamp() -> str:
    return time.strftime("%Y%m%d-%H%M%S", time.gmtime())


def default_artifact_dir() -> pathlib.Path:
    return pathlib.Path("/tmp") / f"lesavka-rct-uvc-artifact-probe-{timestamp()}"


def run_remote(args: argparse.Namespace) -> int:
    local_artifact_dir = pathlib.Path(args.artifact_dir or f"artifacts/rct-uvc/{timestamp()}")
    remote_artifact_dir = args.remote_artifact_dir or f"/tmp/lesavka-rct-uvc-artifact-probe-{timestamp()}"
    remote_script = f"/tmp/lesavka-rct-uvc-artifact-probe-{os.getpid()}.py"
    script_text = pathlib.Path(__file__).read_text()
    subprocess.run(
        ["ssh", args.host, f"cat > {shlex.quote(remote_script)} && chmod +x {shlex.quote(remote_script)}"],
        input=script_text,
        text=True,
        check=True,
    )
    remote_cmd = [
        "python3",
        remote_script,
        "--source",
        args.source,
        "--device",
        args.device,
        "--device-label",
        args.device_label,
        "--display",
        args.display,
        "--crop",
        args.crop,
        "--width",
        str(args.width),
        "--height",
        str(args.height),
        "--fps",
        str(args.fps),
        "--duration",
        str(args.duration),
        "--artifact-dir",
        remote_artifact_dir,
        "--x-step",
        str(args.x_step),
        "--y-step",
        str(args.y_step),
        "--bands",
        str(args.bands),
        "--flat-var",
        str(args.flat_var),
        "--delta-threshold",
        str(args.delta_threshold),
        "--jump-threshold",
        str(args.jump_threshold),
        "--max-suspicious-artifacts",
        str(args.max_suspicious_artifacts),
        "--progress-every",
        str(args.progress_every),
    ]
    print(f"running remote RCT UVC probe on {args.host}: {remote_artifact_dir}", file=sys.stderr)
    rc = subprocess.run(["ssh", args.host, " ".join(shlex.quote(part) for part in remote_cmd)]).returncode
    local_artifact_dir.parent.mkdir(parents=True, exist_ok=True)
    subprocess.run(
        ["scp", "-r", f"{args.host}:{remote_artifact_dir}", str(local_artifact_dir)],
        check=False,
    )
    print(f"artifact_dir: {local_artifact_dir}")
    return rc


def detect_video_device(label: str) -> str:
    explicit = os.environ.get("LESAVKA_RCT_UVC_DEVICE")
    if explicit:
        return explicit
    try:
        listing = subprocess.check_output(["v4l2-ctl", "--list-devices"], text=True)
    except Exception:
        return "/dev/video2"
    current_matches = False
    for line in listing.splitlines():
        if not line.startswith(("\t", " ")):
            current_matches = label.lower() in line.lower()
            continue
        value = line.strip()
        if current_matches and value.startswith("/dev/video"):
            return value
    return "/dev/video2"


def band_stats(frame: bytes, width: int, y0: int, y1: int, x_step: int, y_step: int) -> tuple[float, float]:
    total = 0
    total2 = 0
    count = 0
    view = memoryview(frame)
    for y in range(y0, y1, y_step):
        row = y * width
        for x in range(0, width, x_step):
            value = view[row + x]
            total += value
            total2 += value * value
            count += 1
    if count == 0:
        return 0.0, 0.0
    mean = total / count
    variance = max(0.0, (total2 / count) - (mean * mean))
    return mean, variance


def band_delta(
    frame: bytes, previous: bytes | None, width: int, y0: int, y1: int, x_step: int, y_step: int
) -> float:
    if previous is None:
        return 0.0
    total = 0
    count = 0
    view = memoryview(frame)
    prev = memoryview(previous)
    for y in range(y0, y1, y_step):
        row = y * width
        for x in range(0, width, x_step):
            total += abs(view[row + x] - prev[row + x])
            count += 1
    return total / count if count else 0.0


def max_run(flags: list[bool]) -> int:
    best = 0
    cur = 0
    for flag in flags:
        cur = cur + 1 if flag else 0
        best = max(best, cur)
    return best


def analyze_frame(frame: bytes, previous: bytes | None, args: argparse.Namespace) -> dict[str, Any]:
    width = args.width
    height = args.height
    band_count = max(8, args.bands)
    band_h = max(1, height // band_count)
    means: list[float] = []
    variances: list[float] = []
    for band in range(band_count):
        y0 = band * band_h
        y1 = height if band == band_count - 1 else min(height, y0 + band_h)
        mean, variance = band_stats(frame, width, y0, y1, args.x_step, args.y_step)
        means.append(mean)
        variances.append(variance)

    half = band_count // 2
    lower_flags = [var < args.flat_var for var in variances[half:]]
    lower_flat_pct = sum(lower_flags) / max(1, len(lower_flags))
    lower_flat_run_pct = max_run(lower_flags) / max(1, len(lower_flags))
    upper_delta = band_delta(frame, previous, width, 0, height // 2, args.x_step, args.y_step)
    lower_delta = band_delta(frame, previous, width, height // 2, height, args.x_step, args.y_step)
    jumps = [abs(means[idx] - means[idx - 1]) for idx in range(1, band_count)]
    lower_jumps = jumps[half:]
    max_lower_jump = max(lower_jumps or [0.0])
    sorted_jumps = sorted(jumps)
    median_jump = sorted_jumps[len(sorted_jumps) // 2] if sorted_jumps else 0.0

    reasons: list[str] = []
    temporal_lower_jump = lower_delta > args.delta_threshold and lower_delta > max(upper_delta * 2.2, 8.0)
    lower_delta_skew = temporal_lower_jump
    lower_boundary_jump = (
        temporal_lower_jump
        and max_lower_jump > args.jump_threshold
        and max_lower_jump > max(median_jump * 3.0, 8.0)
    )
    lower_flat_flash = lower_flat_pct >= 0.25 and temporal_lower_jump
    lower_slab = lower_flat_run_pct >= 0.33 and max_lower_jump > args.jump_threshold and temporal_lower_jump
    if lower_delta_skew:
        reasons.append("lower_delta_skew")
    if lower_boundary_jump:
        reasons.append("lower_boundary_jump")
    if lower_flat_flash:
        reasons.append("lower_flat_flash")
    if lower_slab:
        reasons.append("lower_slab")

    suspicious = bool(lower_delta_skew or lower_boundary_jump or lower_flat_flash or lower_slab)
    return {
        "suspicious": suspicious,
        "reasons": reasons,
        "upper_delta": round(upper_delta, 3),
        "lower_delta": round(lower_delta, 3),
        "lower_flat_pct": round(lower_flat_pct, 3),
        "lower_flat_run_pct": round(lower_flat_run_pct, 3),
        "max_lower_jump": round(max_lower_jump, 3),
        "median_band_jump": round(median_jump, 3),
        "lower_variance_min": round(min(variances[half:] or [0.0]), 3),
        "lower_variance_mean": round(sum(variances[half:]) / max(1, len(variances[half:])), 3),
    }


def write_pgm(path: pathlib.Path, frame: bytes, width: int, height: int) -> None:
    path.write_bytes(f"P5\n{width} {height}\n255\n".encode() + frame)


def parse_crop(value: str, args: argparse.Namespace) -> tuple[int, int, int, int]:
    if not value:
        return (0, 0, args.width, args.height)
    parts = [part.strip() for part in value.split(",")]
    if len(parts) != 4:
        raise SystemExit("--crop must be x,y,width,height")
    try:
        x, y, width, height = [int(part) for part in parts]
    except ValueError as exc:
        raise SystemExit("--crop values must be integers") from exc
    if width <= 0 or height <= 0:
        raise SystemExit("--crop width and height must be positive")
    args.width = width
    args.height = height
    return (x, y, width, height)


def ffmpeg_cmd(device: str, args: argparse.Namespace) -> list[str]:
    if args.source == "x11":
        x, y, width, height = parse_crop(args.crop, args)
        display = f"{args.display}+{x},{y}"
        return [
            "ffmpeg",
            "-hide_banner",
            "-nostdin",
            "-loglevel",
            "warning",
            "-f",
            "x11grab",
            "-video_size",
            f"{width}x{height}",
            "-framerate",
            str(args.fps),
            "-i",
            display,
            "-an",
            "-pix_fmt",
            "gray",
            "-f",
            "rawvideo",
            "-",
        ]

    return [
        "ffmpeg",
        "-hide_banner",
        "-nostdin",
        "-loglevel",
        "warning",
        "-f",
        "v4l2",
        "-input_format",
        "mjpeg",
        "-video_size",
        f"{args.width}x{args.height}",
        "-framerate",
        str(args.fps),
        "-i",
        device,
        "-an",
        "-pix_fmt",
        "gray",
        "-f",
        "rawvideo",
        "-",
    ]


def run_capture(args: argparse.Namespace) -> int:
    artifact_dir = pathlib.Path(args.artifact_dir) if args.artifact_dir else default_artifact_dir()
    artifact_dir.mkdir(parents=True, exist_ok=True)
    device = detect_video_device(args.device_label) if args.device == "auto" else args.device
    command = ffmpeg_cmd(device, args)
    (artifact_dir / "command.txt").write_text(" ".join(shlex.quote(part) for part in command) + "\n")
    frame_size = args.width * args.height
    stderr_path = artifact_dir / "ffmpeg.stderr"
    jsonl_path = artifact_dir / "frame-metrics.jsonl"
    started = time.monotonic()
    previous: bytes | None = None
    frame_index = 0
    suspicious_count = 0
    artifacts_written = 0
    reason_counts: collections.Counter[str] = collections.Counter()
    worst: list[dict[str, Any]] = []
    with stderr_path.open("wb") as err, jsonl_path.open("w") as metrics:
        proc = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=err)
        assert proc.stdout is not None
        try:
            while time.monotonic() - started < args.duration:
                frame = proc.stdout.read(frame_size)
                if len(frame) != frame_size:
                    break
                frame_index += 1
                result = analyze_frame(frame, previous, args)
                previous = frame
                result.update({"frame": frame_index, "elapsed_s": round(time.monotonic() - started, 3)})
                if result["suspicious"]:
                    suspicious_count += 1
                    reason_counts.update(result["reasons"])
                    worst.append(result)
                    worst = sorted(
                        worst,
                        key=lambda item: (item["max_lower_jump"], item["lower_delta"]),
                        reverse=True,
                    )[:20]
                    if artifacts_written < args.max_suspicious_artifacts:
                        write_pgm(
                            artifact_dir / f"suspicious_{frame_index:06d}.pgm",
                            frame,
                            args.width,
                            args.height,
                        )
                        artifacts_written += 1
                if frame_index <= 5 or result["suspicious"] or frame_index % args.progress_every == 0:
                    metrics.write(json.dumps(result, sort_keys=True) + "\n")
                if frame_index % args.progress_every == 0:
                    print(
                        f"frames={frame_index} suspicious={suspicious_count} latest={result}",
                        file=sys.stderr,
                    )
        finally:
            proc.terminate()
            try:
                proc.wait(timeout=3)
            except subprocess.TimeoutExpired:
                proc.kill()
    elapsed = max(0.001, time.monotonic() - started)
    summary = {
        "schema": "lesavka.rct-uvc-artifact-probe.v1",
        "source": args.source,
        "device": device,
        "width": args.width,
        "height": args.height,
        "fps_requested": args.fps,
        "duration_requested_s": args.duration,
        "duration_observed_s": round(elapsed, 3),
        "frames": frame_index,
        "fps_observed": round(frame_index / elapsed, 3),
        "suspicious_frames": suspicious_count,
        "suspicious_pct": round((suspicious_count / frame_index * 100.0) if frame_index else 0.0, 3),
        "reason_counts": dict(reason_counts),
        "worst_frames": worst,
        "artifact_dir": str(artifact_dir),
        "ffmpeg_stderr": str(stderr_path),
    }
    (artifact_dir / "summary.json").write_text(json.dumps(summary, indent=2, sort_keys=True) + "\n")
    (artifact_dir / "summary.txt").write_text(format_summary(summary))
    print(format_summary(summary), end="")
    print(f"artifact_dir: {artifact_dir}")
    return 0 if frame_index > 0 else 2


def format_summary(summary: dict[str, Any]) -> str:
    lines = [
        "Lesavka RCT UVC artifact probe",
        f"source: {summary.get('source', 'device')}",
        f"device: {summary['device']}",
        f"mode: {summary['width']}x{summary['height']}@{summary['fps_requested']}",
        f"frames: {summary['frames']} ({summary['fps_observed']} fps observed)",
        f"suspicious: {summary['suspicious_frames']} ({summary['suspicious_pct']}%)",
        f"reasons: {summary['reason_counts']}",
        f"artifacts: {summary['artifact_dir']}",
        "",
    ]
    return "\n".join(lines)


def synthetic_frame(width: int, height: int, shift: int = 0, corrupt: bool = False) -> bytes:
    data = bytearray(width * height)
    for y in range(height):
        row = y * width
        for x in range(width):
            data[row + x] = (x // 8 + y // 4 + shift) % 256
    if corrupt:
        for y in range(height // 2, height):
            row = y * width
            data[row : row + width] = bytes([128]) * width
    return bytes(data)


def run_self_test(args: argparse.Namespace) -> int:
    artifact_dir = pathlib.Path(args.artifact_dir) if args.artifact_dir else default_artifact_dir()
    artifact_dir.mkdir(parents=True, exist_ok=True)
    args.width = 160
    args.height = 90
    frames = [synthetic_frame(args.width, args.height, idx) for idx in range(4)]
    frames.append(synthetic_frame(args.width, args.height, 5, corrupt=True))
    previous = None
    suspicious = 0
    records = []
    for idx, frame in enumerate(frames, start=1):
        result = analyze_frame(frame, previous, args)
        previous = frame
        result["frame"] = idx
        records.append(result)
        if result["suspicious"]:
            suspicious += 1
            write_pgm(artifact_dir / f"selftest_suspicious_{idx:06d}.pgm", frame, args.width, args.height)
    summary = {
        "schema": "lesavka.rct-uvc-artifact-probe.self-test.v1",
        "frames": len(frames),
        "suspicious_frames": suspicious,
        "records": records,
        "artifact_dir": str(artifact_dir),
    }
    (artifact_dir / "summary.json").write_text(json.dumps(summary, indent=2, sort_keys=True) + "\n")
    print(json.dumps(summary, indent=2, sort_keys=True))
    return 0 if suspicious >= 1 else 1


def main() -> int:
    args = parse_args()
    if args.self_test:
        return run_self_test(args)
    if args.host and args.host not in {"localhost", "127.0.0.1"}:
        if not shutil.which("ssh") or not shutil.which("scp"):
            print("ssh and scp are required for --host", file=sys.stderr)
            return 2
        return run_remote(args)
    return run_capture(args)


if __name__ == "__main__":
    raise SystemExit(main())