"""Download NUTS-2 boundary GeoJSON from Eurostat GISCO.

One-time (or on NUTS revision) download of NUTS-2 boundary polygons used for
spatial income resolution in dim_locations. Stored uncompressed because DuckDB's
ST_Read function cannot read gzipped files.

NUTS classification changes approximately every 7 years. Current revision: 2021.

Output: {LANDING_DIR}/gisco/2024/01/nuts2_boundaries.geojson  (~5MB, uncompressed)

Usage:
    uv run python scripts/download_gisco_nuts.py [--landing-dir data/landing]

Idempotent: skips download if the file already exists.
"""

import argparse
import sys
from pathlib import Path

import niquests

# NUTS 2021 revision, 20M scale (1:20,000,000), WGS84 (EPSG:4326), LEVL_2 only.
# 20M resolution gives simplified polygons that are fast for point-in-polygon
# matching without sacrificing accuracy at the NUTS-2 boundary level.
GISCO_URL = (
    "https://gisco-services.ec.europa.eu/distribution/v2/nuts/geojson/"
    "NUTS_RG_20M_2021_4326_LEVL_2.geojson"
)

# Fixed partition: NUTS boundaries are a static reference file, not time-series data.
# Use the NUTS revision year as the partition to make the source version explicit.
DEST_REL_PATH = "gisco/2024/01/nuts2_boundaries.geojson"

HTTP_TIMEOUT_SECONDS = 120


def download_nuts_boundaries(landing_dir: Path) -> None:
    dest = landing_dir / DEST_REL_PATH
    if dest.exists():
        print(f"Already exists (skipping): {dest}")
        return

    dest.parent.mkdir(parents=True, exist_ok=True)
    print(f"Downloading NUTS-2 boundaries from GISCO...")
    print(f"  URL: {GISCO_URL}")

    with niquests.Session() as session:
        resp = session.get(GISCO_URL, timeout=HTTP_TIMEOUT_SECONDS)
        resp.raise_for_status()

    content = resp.content
    assert len(content) > 100_000, (
        f"GeoJSON too small ({len(content)} bytes) — download may have failed"
    )
    assert b'"FeatureCollection"' in content, "Response does not look like GeoJSON"

    # Write uncompressed — ST_Read requires a plain file
    tmp = dest.with_suffix(".geojson.tmp")
    tmp.write_bytes(content)
    tmp.rename(dest)

    size_mb = len(content) / 1_000_000
    print(f"  Written: {dest} ({size_mb:.1f} MB)")
    print("Done. Run SQLMesh plan to rebuild stg_nuts2_boundaries.")


def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--landing-dir", default="data/landing", type=Path)
    args = parser.parse_args()

    if not args.landing_dir.is_dir():
        print(f"Error: landing dir does not exist: {args.landing_dir}", file=sys.stderr)
        sys.exit(1)

    download_nuts_boundaries(args.landing_dir)


if __name__ == "__main__":
    main()