Descargar KuDE

GET /api/v1/documento-electronico/:cdc/kude

api_origin="https://api.sifende.com.py"
url_inicial="$api_origin/api/v1/documento-electronico/$CDC/kude"
url="$url_inicial"
limite=$((SECONDS + 120))
volvio_a_pedir=0

while true; do
  status=$(curl -sS -D headers.txt -o respuesta.bin -w '%{http_code}' \
    "$url" \
    -H "Authorization: Bearer $SIFENDE_API_KEY")

  if [ "$status" = "200" ]; then
    mv respuesta.bin factura.pdf
    break
  fi

  if [ "$status" = "202" ]; then
    location=$(awk 'tolower($1)=="location:" {print $2}' headers.txt | tr -d '\r')
    sleep "$(awk 'tolower($1)=="retry-after:" {print $2}' headers.txt | tr -d '\r')"
    if [ "$SECONDS" -lt "$limite" ]; then
      url="$api_origin$location"
    elif [ "$volvio_a_pedir" = 0 ]; then
      volvio_a_pedir=1
      url="$url_inicial"
      limite=$((SECONDS + 120))
    else
      echo "KuDE pendiente por más de 4 minutos; contactá a soporte" >&2
      exit 1
    fi
    continue
  fi

  cat respuesta.bin >&2
  exit 1
done

import { writeFile } from 'node:fs/promises';

type ProblemDetail = {
  type: string;
  title: string;
  status: number;
  detail: string;
  traceId?: string;
};

async function esperar(ms: number): Promise<void> {
  await new Promise(resolve => setTimeout(resolve, ms));
}

async function descargarKuDE(cdc: string, destino: string): Promise<void> {
  const urlInicial = `https://api.sifende.com.py/api/v1/documento-electronico/${cdc}/kude`;
  let url = urlInicial;
  let limite = Date.now() + 2 * 60_000;
  let volvioAPedir = false;

  for (;;) {
    const res = await fetch(url, {
      headers: { Authorization: `Bearer ${process.env.SIFENDE_API_KEY}` },
    });

    if (res.status === 200 && res.headers.get('content-type')?.includes('application/pdf')) {
      const buffer = Buffer.from(await res.arrayBuffer());
      await writeFile(destino, buffer);
      return;
    }

    if (res.status === 202) {
      const location = res.headers.get('location');
      if (!location) throw new Error('KuDE pendiente sin Location');
      await res.json();
      await esperar(Number(res.headers.get('retry-after') ?? '5') * 1000);
      if (Date.now() < limite) {
        url = new URL(location, url).toString();
      } else if (!volvioAPedir) {
        volvioAPedir = true;
        url = urlInicial;
        limite = Date.now() + 2 * 60_000;
      } else {
        throw new Error('KuDE pendiente por más de 4 minutos; contactá a soporte');
      }
      continue;
    }

    const problem = await res.json() as ProblemDetail;
    throw new Error(`No se pudo descargar KuDE (${problem.status}): ${problem.type}`);
  }
}

await descargarKuDE(
  '01800123451001001000000122026042710000000006',
  './kude/factura-001.pdf'
);

import express from 'express';

const app = express();

app.get('/facturas/:cdc/kude', async (req, res) => {
  let url = `https://api.sifende.com.py/api/v1/documento-electronico/${req.params.cdc}/kude`;
  const limite = Date.now() + 2 * 60_000;

  for (;;) {
    const upstream = await fetch(url, {
      headers: { Authorization: `Bearer ${process.env.SIFENDE_API_KEY}` },
    });

    if (upstream.status === 200 && upstream.headers.get('content-type')?.includes('application/pdf')) {
      res.setHeader('Content-Type', 'application/pdf');
      res.setHeader('Content-Disposition', `inline; filename="factura-${req.params.cdc}.pdf"`);
      const reader = upstream.body!.getReader();
      while (true) {
        const { value, done } = await reader.read();
        if (done) break;
        res.write(value);
      }
      res.end();
      return;
    }

    if (upstream.status === 202) {
      const location = upstream.headers.get('location');
      if (!location) return res.status(502).json({ error: 'KuDE pendiente sin Location' });
      await upstream.json();
      if (Date.now() >= limite) return res.status(503).json({ error: 'KuDE todavía en preparación; reintentá más tarde' });
      await new Promise(resolve => setTimeout(resolve, Number(upstream.headers.get('retry-after') ?? '5') * 1000));
      url = new URL(location, url).toString();
      continue;
    }

    return res.status(upstream.status).json(await upstream.json());
  }
});