Fastify

CONSTAIA_API_KEY=ck_test_...
CONSTAIA_WEBHOOK_SECRET=whsec_...

import {
  AuthenticationError,
  Constaia,
  ConstaiaError,
  InsufficientCreditsError,
  InvalidRequestError,
  PermissionError,
  RateLimitError,
  type Analysis,
  type WebhookEvent,
} from "@constaia/sdk";

// Lee CONSTAIA_API_KEY del entorno.
export const constaia = new Constaia();

// Lo que devuelves al navegador (y lo que pinta el widget): sin los campos extraídos.
export function publicResult(analysis: Analysis) {
  const { id, object, status, document, verdict, warnings } = analysis;
  return { id, object, status, document, verdict, warnings };
}

export type HttpError = {
  status: number;
  body: { error: { code: string; message: string } };
  retryAfter?: number;
};

const httpError = (status: number, code: string, message: string, retryAfter?: number): HttpError => ({
  status,
  body: { error: { code, message } },
  retryAfter,
});

export function toHttpError(error: unknown): HttpError {
  if (error instanceof InvalidRequestError) {
    // Fichero ilegible, formato no admitido, demasiadas páginas…: el usuario puede corregirlo.
    return httpError(error.status === 413 ? 413 : 422, error.code ?? "invalid_request", error.message);
  }
  if (error instanceof RateLimitError) {
    const wait = Math.ceil(error.retryAfter ?? 1);
    return httpError(429, "rate_limited", "Demasiadas peticiones. Inténtalo en unos segundos.", wait);
  }
  if (error instanceof InsufficientCreditsError) {
    console.error("[constaia] Sin créditos. Recarga en https://app.constaia.com", error.requestId);
    return httpError(503, "unavailable", "La validación no está disponible ahora mismo.");
  }
  if (error instanceof AuthenticationError || error instanceof PermissionError) {
    console.error("[constaia] Revisa CONSTAIA_API_KEY", error.code, error.requestId);
    return httpError(500, "misconfigured", "Error de configuración del servidor.");
  }
  if (error instanceof ConstaiaError) {
    // APIError (5xx), APIConnectionError, APITimeoutError
    console.error("[constaia]", error.name, error.code, error.requestId);
    return httpError(502, "upstream_error", "No se ha podido analizar el documento. Inténtalo de nuevo.");
  }
  console.error(error);
  return httpError(500, "internal_error", "Error interno.");
}

// Deduplicación por webhook-id. En producción, una tabla con clave única.
const processed = new Set<string>();
export const alreadyProcessed = (webhookId: string) => processed.has(webhookId);
export const markProcessed = (webhookId: string) => void processed.add(webhookId);

export async function handleEvent(event: WebhookEvent) {
  switch (event.type) {
    case "analysis.completed":
      // event.data es el análisis completo (con fields). Guárdalo por event.data.id.
      console.log("analysis.completed", event.data.id, event.data.verdict?.status);
      break;
    case "analysis.review_required":
      console.log("A revisión manual", event.data.id);
      break;
    case "analysis.failed":
      console.warn("analysis.failed", event.data.id, event.data.error?.code);
      break;
    case "credits.low":
      console.warn("Quedan pocos créditos: recarga en https://app.constaia.com");
      break;
  }
}

import Fastify from "fastify";
import multipart from "@fastify/multipart";
import { WebhookVerificationError } from "@constaia/sdk";
import {
  alreadyProcessed,
  constaia,
  handleEvent,
  markProcessed,
  publicResult,
  toHttpError,
} from "./constaia.js";

const app = Fastify({ logger: true });

await app.register(multipart, {
  limits: { fileSize: 20 * 1024 * 1024, files: 1, fields: 5 },
});

// Aquí va tu autenticación (por ejemplo un hook onRequest): cada llamada gasta créditos.
app.post("/api/verify-dni", async (request, reply) => {
  let file: { buffer: Buffer; filename: string } | undefined;
  let fullName = "";

  for await (const part of request.parts()) {
    if (part.type === "file" && part.fieldname === "file") {
      // toBuffer() lanza un error 413 si supera limits.fileSize.
      file = { buffer: await part.toBuffer(), filename: part.filename };
    } else if (part.type === "file") {
      part.file.resume();
    } else if (part.fieldname === "full_name") {
      fullName = String(part.value).trim();
    }
  }

  if (!file) {
    return reply.code(400).send({ error: { code: "missing_file", message: "Falta el fichero." } });
  }

  try {
    const analysis = await constaia.analyze(file.buffer, {
      filename: file.filename,
      expect: "es_dni",
      checks: { notExpired: true, ...(fullName ? { holder: { fullName } } : {}) },
      storage: "none",
      language: "es",
    });
    // Guarda analysis.id y analysis.verdict en tu base de datos.
    return reply.code(analysis.status === "completed" ? 200 : 202).send(publicResult(analysis));
  } catch (error) {
    const { status, body, retryAfter } = toHttpError(error);
    if (retryAfter) reply.header("Retry-After", retryAfter);
    return reply.code(status).send(body);
  }
});

// Contexto encapsulado: el parser de cuerpo crudo solo afecta a esta ruta.
await app.register(async (scope) => {
  scope.addContentTypeParser("application/json", { parseAs: "string" }, (_request, body, done) => {
    done(null, body);
  });

  scope.post("/webhooks/constaia", async (request, reply) => {
    let event;
    try {
      event = await constaia.webhooks.verify(
        request.body as string,
        request.headers,
        process.env.CONSTAIA_WEBHOOK_SECRET!,
      );
    } catch (error) {
      if (error instanceof WebhookVerificationError) return reply.code(400).send("Invalid signature");
      throw error;
    }

    const webhookId = request.headers["webhook-id"] as string;
    if (!alreadyProcessed(webhookId)) {
      await handleEvent(event);
      markProcessed(webhookId);
    }
    return reply.code(200).send();
  });
});

await app.listen({ port: Number(process.env.PORT ?? 3000), host: "0.0.0.0" });

npx tsx --env-file=.env src/server.ts

{
  "id": "an_01J…",
  "object": "analysis",
  "status": "completed",
  "document": { "type": "es_dni", "label": "DNI (España)", "confidence": 0.97, "side": "both", "country": "ESP" },
  "verdict": {
    "expected": ["es_dni"],
    "match": true,
    "status": "valid",
    "reasons": [
      { "code": "type_match", "severity": "info", "message": "El documento es DNI (España)." },
      { "code": "not_expired", "severity": "info", "message": "Vigente hasta el 12/03/2031." },
      { "code": "holder", "severity": "info", "message": "Los datos del titular coinciden (full_name)." }
    ]
  },
  "warnings": []
}

curl -F "file=@dni_valid.jpg" -F "full_name=María García López" http://localhost:3000/api/verify-dni

import { signWebhook } from "@constaia/sdk";

const payload = JSON.stringify({
  type: "analysis.completed",
  created_at: new Date().toISOString(),
  data: { id: "an_test", object: "analysis", status: "completed", verdict: { status: "valid", reasons: [] } },
});
const headers = await signWebhook(payload, process.env.CONSTAIA_WEBHOOK_SECRET!);

const res = await app.inject({
  method: "POST",
  url: "/webhooks/constaia",
  headers: { ...headers, "content-type": "application/json" },
  payload,
});
console.log(res.statusCode); // 200