/**
 * LandveX Finance — Prometheus Metrics
 * Sprint 3: Observability
 */
import promClient from 'prom-client';

const registry = new promClient.Registry();

// ── Journal / Verifikat ──
export const journalCounter = new promClient.Counter({
  name: 'finance_journal_entries_total',
  help: 'Total journal entries created',
  labelNames: ['tenant', 'period', 'status'],
  registers: [registry],
});

export const journalAmount = new promClient.Counter({
  name: 'finance_journal_amount_total',
  help: 'Total journal amount by direction',
  labelNames: ['tenant', 'period', 'direction'],
  registers: [registry],
});

// ── Invoices / Fakturor ──
export const invoiceGauge = new promClient.Gauge({
  name: 'finance_invoices_total',
  help: 'Total invoices by status',
  labelNames: ['tenant', 'status'],
  registers: [registry],
});

// ── VAT / Moms ──
export const vatGauge = new promClient.Gauge({
  name: 'finance_vat_payable',
  help: 'VAT payable to tax authority',
  labelNames: ['tenant', 'period'],
  registers: [registry],
});

// ── Payroll / Löner ──
export const payrollGauge = new promClient.Gauge({
  name: 'finance_payroll_total',
  help: 'Total payroll cost for period',
  labelNames: ['tenant', 'period'],
  registers: [registry],
});

// ── Receipts / Kvitton ──
export const receiptCounter = new promClient.Counter({
  name: 'finance_receipts_uploaded_total',
  help: 'Total receipts uploaded',
  labelNames: ['tenant'],
  registers: [registry],
});

// ── API Performance ──
export const apiHistogram = new promClient.Histogram({
  name: 'finance_api_duration_seconds',
  help: 'Finance API endpoint duration',
  labelNames: ['endpoint', 'method', 'status'],
  buckets: [0.01, 0.05, 0.1, 0.3, 0.5, 1, 2, 5],
  registers: [registry],
});

// ── Period Close ──
export const periodCloseCounter = new promClient.Counter({
  name: 'finance_period_closures_total',
  help: 'Period closures attempted',
  labelNames: ['tenant', 'period', 'result'],
  registers: [registry],
});

// ── Health Check Duration ──
export const healthCheckDuration = new promClient.Histogram({
  name: 'finance_health_check_duration_ms',
  help: 'Health check duration in milliseconds',
  labelNames: ['check'],
  buckets: [1, 5, 10, 25, 50, 100, 250, 500],
  registers: [registry],
});

// ── Disk Usage ──
export const diskGauge = new promClient.Gauge({
  name: 'finance_disk_used_percent',
  help: 'Disk usage percentage',
  labelNames: ['path'],
  registers: [registry],
});

// ── Helper: timed API call ──
export async function timedAPI(endpoint, method, fn) {
  const end = apiHistogram.startTimer();
  try {
    const result = await fn();
    end({ endpoint, method, status: 'success' });
    return result;
  } catch (e) {
    end({ endpoint, method, status: 'error' });
    throw e;
  }
}

// ── Export all metrics ──
export function getMetrics() {
  return registry.metrics();
}

export function getContentType() {
  return registry.contentType;
}