import json
from collections import defaultdict

input_filename = "../data/cerc_cmm_corrected.geojson"

with open(input_filename, "r", encoding="utf-8") as f:
    data = json.load(f)

if data.get("type") != "FeatureCollection":
    raise ValueError("Input GeoJSON does not have type 'FeatureCollection'.")

features_by_region = defaultdict(list)

for feature in data.get("features", []):
    region = feature["properties"].get("region", "unknown_region")
    features_by_region[region].append(feature)

for region_name, features in features_by_region.items():
    out_data = {
        "type": "FeatureCollection",
        "crs": data.get("crs", None),
        "features": features
    }

    output_filename = f"output_{region_name}.geojson"

    with open(output_filename, "w", encoding="utf-8") as outfile:
        json.dump(out_data, outfile, ensure_ascii=False, indent=2)

    print(f"Created {output_filename} with {len(features)} features.")