from datetime import time, date, datetime, timedelta

def horari_descans(ti, tf, dia, dd):
    dti, dtf = datetime.combine(dia, ti), datetime.combine(dia, tf)
    if timedelta(0) < dd < dtf-dti:
        m = (dtf-dti)/2
        return True, dti+m-(dd/2), dti+m+(dd/2)
    else:
        return False, dti, dtf