"""Build src/static/flood-marks-2024.json from CMU Water Center's flood marks.

After the October 2024 flood (P.1 peaked at 5.30 m on 5 October), CMU Water
Center marked the high-water line at about 5,000 places in Chiang Mai and
Lamphun (CMFlood, "Flood marks 2024"): the depth above the road surface, in
cm. This keeps position and depth only, in a compact array form:

    uv run python scripts/build_flood_marks.py              # fetch from CMU
    uv run python scripts/build_flood_marks.py --geojson F  # or a saved copy
"""

import argparse
import json
import urllib.request
from pathlib import Path

REPO = Path(__file__).resolve().parents[1]
OUT = REPO / "src" / "static" / "flood-marks-2024.json"
URL = "https://watercenter.cmu.ac.th/data/New_floodMark_2025_fixed_like_pole.geojson"
SOURCE = (
    "CMU Water Center (ศูนย์วิชาการสนับสนุนการบริหารจัดการน้ำ มหาวิทยาลัยเชียงใหม่), "
    "flood marks of October 2024, "
    "https://watercenter.cmu.ac.th/chiangmai/cmflood/warning/floodmark"
)


def load(path: Path | None) -> dict:
    if path:
        return json.loads(path.read_text(encoding="utf-8"))
    req = urllib.request.Request(URL, headers={"User-Agent": "Mozilla/5.0"})
    with urllib.request.urlopen(req, timeout=120) as r:
        return json.loads(r.read().decode("utf-8"))


def main() -> None:
    ap = argparse.ArgumentParser(description=__doc__.splitlines()[0])
    ap.add_argument("--geojson", type=Path, help="read CMU's GeoJSON from here")
    args = ap.parse_args()

    marks, skipped = [], 0
    for f in load(args.geojson)["features"]:
        p = f.get("properties") or {}
        lon, lat, depth = p.get("longitude"), p.get("latitude"), p.get("water_level")
        if lon is None or lat is None or depth is None:
            skipped += 1
            continue
        # 18-19.5 N, 98.5-99.5 E: a swapped or empty coordinate is skipped
        if not (18.0 < lat < 19.5 and 98.5 < lon < 99.5) or depth <= 0:
            skipped += 1
            continue
        marks.append([round(lon, 5), round(lat, 5), round(depth)])
    marks.sort(key=lambda m: (m[1], m[0]))
    doc = {
        "source": SOURCE,
        "p1_level": 5.30,
        "date": "2024-10-05",
        "fields": ["lon", "lat", "depth_cm_above_road"],
        "marks": marks,
    }
    OUT.write_text(
        json.dumps(doc, ensure_ascii=False, separators=(",", ":")) + "\n",
        encoding="utf-8",
    )
    print(
        f"wrote {OUT.relative_to(REPO)}: {len(marks)} marks, {skipped} skipped, "
        f"{OUT.stat().st_size / 1024:.0f} KB"
    )


if __name__ == "__main__":
    main()