import { normalizeOrgChartDataset } from './normalize.js';
import type { ApprovedAggregationPolicy, Employee, OrgChartDataset, OrgChartSummary, SummaryCounts, WorkStatus } from './types.js';

const statuses: WorkStatus[] = ['active', 'dispatched', 'onLeave'];
function supportedPolicy(policy: ApprovedAggregationPolicy): boolean {
  const validStatuses = (values: unknown): values is WorkStatus[] => Array.isArray(values)
    && values.every(value => statuses.includes(value)) && new Set(values).size === values.length;
  return !!policy && typeof policy.policyVersion === 'string' && !!policy.policyVersion.trim()
    && !/[\u0000-\u001f<>]/.test(policy.policyVersion)
    && validStatuses(policy.includedStatuses) && validStatuses(policy.activeStatuses)
    && policy.activeStatuses.every(status => policy.includedStatuses.includes(status))
    && policy.includeLeaders === true && policy.membershipMode === 'primaryOnly';
}
function count(data: OrgChartDataset, employees: readonly Employee[]): SummaryCounts {
  const counts: SummaryCounts = {
    total: 0,
    byOrganization: Object.create(null) as SummaryCounts['byOrganization'],
    byPosition: Object.create(null) as SummaryCounts['byPosition'],
    byAffiliation: Object.create(null) as SummaryCounts['byAffiliation'],
    byStatus: { active: 0, dispatched: 0, onLeave: 0 },
  };
  for (const org of data.organizations) counts.byOrganization[org.id] = { direct: 0, inclusive: 0 };
  for (const affiliation of data.affiliations) counts.byAffiliation[affiliation.id] = 0;
  const seen = new Set<string>();
  for (const employee of employees) {
    if (seen.has(employee.id)) continue;
    seen.add(employee.id);
    counts.total += 1;
    counts.byOrganization[employee.organizationId]!.direct += 1;
    counts.byPosition[employee.position] = (counts.byPosition[employee.position] ?? 0) + 1;
    counts.byAffiliation[employee.affiliationId] = (counts.byAffiliation[employee.affiliationId] ?? 0) + 1;
    counts.byStatus[employee.workStatus] += 1;
  }
  // Single primary membership makes child totals disjoint; compute a postorder iteratively.
  const stack = [...normalizeOrgChartDataset(data).roots];
  const traversal = [];
  while (stack.length) {
    const node = stack.pop()!;
    traversal.push(node);
    stack.push(...node.children);
  }
  for (let index = traversal.length - 1; index >= 0; index--) {
    const node = traversal[index]!;
    counts.byOrganization[node.organization.id]!.inclusive = counts.byOrganization[node.organization.id]!.direct
      + node.children.reduce((sum, child) => sum + counts.byOrganization[child.organization.id]!.inclusive, 0);
  }
  return counts;
}
/** Raw counts are literal unique employee IDs, independent of presentation or business totals. */
export function calculateSummary(data: OrgChartDataset, policy?: ApprovedAggregationPolicy): OrgChartSummary {
  const raw = count(data, data.employees);
  if (!policy) return { raw, aggregation: { status: 'unavailable', reason: 'policyRequired' } };
  if (!supportedPolicy(policy)) return { raw, aggregation: { status: 'unavailable', reason: 'unsupportedPolicy' } };
  const selected = data.employees.filter(employee => policy.includedStatuses.includes(employee.workStatus));
  return { raw, aggregation: { status: 'ready', policyVersion: policy.policyVersion, counts: count(data, selected) } };
}