chore: add custom header for createClient (#16)

Because

- add custom header for createClient

This commit

- add custom header for createClient

src/helper/createClient.ts

@@ -1,39 +1,40 @@
-import axios from "axios";
+import axios, { AxiosHeaders } from "axios";
 import { env } from "./config";
 import { Nullable } from "../types";
 
 export function createClient(
   accessToken: Nullable<string>,
-  product: "base" | "model" | "vdp"
+  product: "base" | "model" | "vdp",
+  headers: AxiosHeaders
 ) {
-  const headers = accessToken
-    ? {
+  let clientHeaders = {};
+
+  if (headers) {
+    clientHeaders = headers;
+  } else {
+    if (accessToken) {
+      clientHeaders = {
         Authorization: `Bearer ${accessToken}`,
         "CF-Access-Client-Id": env("CF_ACCESS_CLIENT_ID")
           ? env("CF_ACCESS_CLIENT_ID")
           : undefined,
         "CF-Access-Client-Secret": env("CF_ACCESS_CLIENT_SECRET")
           ? env("CF_ACCESS_CLIENT_SECRET")
           : undefined,
-      }
-    : {};
+      };
+    }
+  }
 
-  if (
-    !process.env.API_GATEWAY_URL &&
-    !env("API_GATEWAY_URL")
-  ) {
-    throw new Error(
-      "API_GATEWAY_URL or API_GATEWAY_URL is not defined"
-    );
+  if (!process.env.API_GATEWAY_URL && !env("API_GATEWAY_URL")) {
+    throw new Error("API_GATEWAY_URL or API_GATEWAY_URL is not defined");
   }
 
   let baseURL: Nullable<string> = `${
-    process.env.API_GATEWAY_URL ??
-    env("API_GATEWAY_URL")
+    process.env.API_GATEWAY_URL ?? env("API_GATEWAY_URL")
   }/${product}/${env("API_VERSION")}`;
 
   return axios.create({
     baseURL,
-    headers,
+    headers: clientHeaders,
   });
 }