"""Run against the supplied sample dataset.json; no dependencies or network."""
import csv, json, sys
from pathlib import Path
data=json.loads(Path(sys.argv[1] if len(sys.argv)>1 else 'dataset.json').read_text(encoding='utf-8'))
fields=['project_key','name_en','metal','country_code','production_value','production_period_start','production_period_end','capacity_value','capacity_unit','capacity_effective_date','entity_scope']
rows=[{k:r.get(k) for k in fields} for r in data['projects'] if r['country_code'] in ('CN','KR') and r['metal'] in ('lead','zinc') and r['layer']=='processing']
with Path('research-case.csv').open('w',encoding='utf-8-sig',newline='') as f:
    out=csv.DictWriter(f,fieldnames=fields);out.writeheader();out.writerows(rows)
print(f'Wrote {len(rows)} project-metal entries. Blank quantities/dates stay unknown.')