import axios, { AxiosError, InternalAxiosRequestConfig } from "axios";
// Create an axios instance with the base URL for Semantic Scholar API
const semanticScholarClient = axios.create({
baseURL: "https://api.semanticscholar.org/graph/v1",
headers: {
"Content-Type": "application/json",
},
});
// Add API key if available from environment (fallback)
if (process.env.SEMANTIC_SCHOLAR_API_KEY) {
semanticScholarClient.defaults.headers.common["x-api-key"] =
process.env.SEMANTIC_SCHOLAR_API_KEY;
}
// Track last request time for rate-limited endpoints
const lastRequestTime: Record<string, number> = {
"/paper/batch": 0,
"/paper/search": 0,
"/author/batch": 0,
"/recommendations": 0,
default: 0,
};
// Add request interceptor for rate limiting
semanticScholarClient.interceptors.request.use(
async (config: InternalAxiosRequestConfig) => {
// Determine which rate limit applies
let endpoint = "default";
const url = config.url || "";
if (url.startsWith("/paper/batch")) {
endpoint = "/paper/batch";
} else if (url.startsWith("/paper/search")) {
endpoint = "/paper/search";
} else if (url.startsWith("/author/batch")) {
endpoint = "/author/batch";
} else if (url.startsWith("/recommendations")) {
endpoint = "/recommendations";
}
const now = Date.now();
const lastRequest = lastRequestTime[endpoint];
// Calculate delay needed based on endpoint
const minInterval = endpoint === "default" ? 100 : 1000; // 10 req/sec or 1 req/sec
const timeElapsed = now - lastRequest;
const delayNeeded = Math.max(0, minInterval - timeElapsed);
if (delayNeeded > 0) {
await new Promise((resolve) => setTimeout(resolve, delayNeeded));
}
// Update last request time
lastRequestTime[endpoint] = Date.now();
return config;
},
(error) => Promise.reject(error)
);
// Add response interceptor for handling rate limit errors
semanticScholarClient.interceptors.response.use(
(response) => response,
async (error: AxiosError) => {
const originalRequest = error.config;
// Check if error is due to rate limiting (429 Too Many Requests)
if (error.response?.status === 429 && originalRequest) {
console.warn(
"Rate limit exceeded for Semantic Scholar API. Retrying after delay..."
);
// Wait for appropriate time based on endpoint
const url = originalRequest.url || "";
const delay =
url.startsWith("/paper/batch") ||
url.startsWith("/paper/search") ||
url.startsWith("/author/batch") ||
url.startsWith("/recommendations")
? 1000
: 100;
await new Promise((resolve) => setTimeout(resolve, delay));
// Retry the request
return semanticScholarClient(originalRequest);
}
return Promise.reject(error);
}
);
export default semanticScholarClient;
