#!/usr/bin/env python3
"""Verify the supplied artifact and reproduce the server-accepted CTF flag."""

from __future__ import annotations

import argparse
import hashlib
from decimal import Decimal, ROUND_DOWN
from pathlib import Path


EXPECTED_SHA256 = "1d8d606687e584e176a700ca426b237dc3077ea075acec3d8f8114f307690273"

# Exilenova+ post 11115 labels these as the phone operator's Lat,Long.
OPERATOR_LAT = Decimal("43.431717894702786")
OPERATOR_LON = Decimal("39.93346527459446")


def sha256(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as stream:
        for chunk in iter(lambda: stream.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def truncate_three_decimals(value: Decimal) -> str:
    """Match the challenge validator: truncate positive coordinates to 3 dp."""
    return str(value.quantize(Decimal("0.001"), rounding=ROUND_DOWN))


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "video",
        nargs="?",
        type=Path,
        default=Path(__file__).with_name("Drone.mp4"),
    )
    args = parser.parse_args()

    actual = sha256(args.video)
    if actual != EXPECTED_SHA256:
        raise SystemExit(
            f"unexpected attachment SHA-256: {actual}\nexpected: {EXPECTED_SHA256}"
        )

    # The live validator contradicts the displayed Long,Lat instruction. It
    # accepts Lat, Long, truncated to three decimals, including this spacing.
    print(
        "RTRTNI26{"
        f"{truncate_three_decimals(OPERATOR_LAT)}, "
        f"{truncate_three_decimals(OPERATOR_LON)}"
        "}"
    )


if __name__ == "__main__":
    main()