deer-flow/frontend/src/core/api/api-client.ts

"use client";

import { Client as LangGraphClient } from "@langchain/langgraph-sdk/client";

import { getLangGraphBaseURL } from "../config";

import { isStateChangingMethod, readCsrfCookie } from "./fetcher";
import { sanitizeRunStreamOptions } from "./stream-mode";

/**
 * SDK ``onRequest`` hook that mints the ``X-CSRF-Token`` header from the
 * live ``csrf_token`` cookie just before each outbound fetch.
 *
 * Reading the cookie per-request (rather than baking it into the SDK's
 * ``defaultHeaders`` at construction) handles login / logout / password
 * change cookie rotation transparently. Both the ``/api/langgraph/*`` SDK
 * path and the direct REST endpoints in ``fetcher.ts:fetchWithAuth``
 * share :func:`readCsrfCookie` and :const:`STATE_CHANGING_METHODS` so
 * the contract stays in lockstep.
 */
function injectCsrfHeader(_url: URL, init: RequestInit): RequestInit {
  if (!isStateChangingMethod(init.method ?? "GET")) {
    return init;
  }
  const token = readCsrfCookie();
  if (!token) return init;
  const headers = new Headers(init.headers);
  if (!headers.has("X-CSRF-Token")) {
    headers.set("X-CSRF-Token", token);
  }
  return { ...init, headers };
}

function createCompatibleClient(isMock?: boolean): LangGraphClient {
  const apiUrl = getLangGraphBaseURL(isMock);
  console.log(`Creating API client with base URL: ${apiUrl}`);
  const client = new LangGraphClient({
    apiUrl,
    onRequest: injectCsrfHeader,
  });

  const originalRunStream = client.runs.stream.bind(client.runs);
  client.runs.stream = ((threadId, assistantId, payload) =>
    originalRunStream(
      threadId,
      assistantId,
      sanitizeRunStreamOptions(payload),
    )) as typeof client.runs.stream;

  const originalJoinStream = client.runs.joinStream.bind(client.runs);
  client.runs.joinStream = ((threadId, runId, options) =>
    originalJoinStream(
      threadId,
      runId,
      sanitizeRunStreamOptions(options),
    )) as typeof client.runs.joinStream;

  return client;
}

const _clients = new Map<string, LangGraphClient>();
export function getAPIClient(isMock?: boolean): LangGraphClient {
  const cacheKey = isMock ? "mock" : "default";
  let client = _clients.get(cacheKey);

  if (!client) {
    client = createCompatibleClient(isMock);
    _clients.set(cacheKey, client);
  }

  return client;
}