function categoryForTemplate(template, categories = []) {
  const keywords = template?.categoryKeywords || [];
  const match = categories.find(category => {
    const name = String(category.name || '').toLowerCase();
    return keywords.some(keyword => name.includes(keyword));
  });
  return match?.id ?? null;
}

function categoryIdOrFallback(categoryId, template, categories = []) {
  if (categoryId && categories.some(category => String(category.id) === String(categoryId))) {
    return categoryId;
  }
  return template ? categoryForTemplate(template, categories) : null;
}

export function makeBillDraft(source, { copy = false, template = null, categories = [] } = {}) {
  const data = source || {};
  return {
    ...data,
    id: undefined,
    source_bill_id: copy && data.id != null ? data.id : undefined,
    active: 1,
    name: copy
      ? `${data.name || 'Bill'} (Copy)`
      : (data.name || template?.name || ''),
    category_id: categoryIdOrFallback(data.category_id, template, categories),
    due_day: data.due_day || 1,
    expected_amount: data.expected_amount ?? 0,
    billing_cycle: data.billing_cycle || 'monthly',
    cycle_type: data.cycle_type || 'monthly',
    cycle_day: String(data.cycle_day || '1'),
    autopay_enabled: !!data.autopay_enabled,
    autodraft_status: data.autodraft_status || (data.autopay_enabled ? 'assumed_paid' : 'none'),
    auto_mark_paid: !!data.auto_mark_paid,
    has_2fa: !!data.has_2fa,
    snowball_include: !!data.snowball_include,
    snowball_exempt: !!data.snowball_exempt,
  };
}