"""Reproduce section 5 of CLA's report. Python standard library only.
Conditional arithmetic, not an official estimate or a probability interval.
Inputs: report sources 1 and 25; population vintage 1 October 2026.
"""
import csv,sys
UK,ENGLAND,WALES=69483900,58834800,3175200
CASES=[('Central six-drug input / lower cannabis model',12,2.3),('Central six-drug input / alternative cannabis model',12,3.6),('Lower arithmetic stress test',7.1,2.3),('Upper arithmetic stress test',16.9,3.6)]
def scenario(s,c):
    return s*UK/ENGLAND+c*UK/(ENGLAND+WALES)
if __name__=='__main__':
    writer=csv.writer(sys.stdout)
    writer.writerow(['case','six_drug_england_gbp_bn','cannabis_england_wales_gbp_bn','uk_population','england_population','wales_population','uk_conditional_gbp_bn','interpretation'])
    for label,s,c in CASES:
        writer.writerow([label,s,c,UK,ENGLAND,WALES,f'{scenario(s,c):.8f}','Conditional scenario; equal per-resident spending assumed; not a confidence interval or 2026 forecast'])