feat: add flow account service

src/services/flowaccount.ts

@@ -0,0 +1,52 @@
+if (!process.env.FLOW_ACCOUNT_URL) throw new Error("Require FLOW_ACCOUNT_URL");
+if (!process.env.FLOW_ACCOUNT_CLIENT_ID) throw new Error("Require FLOW_ACCOUNT_CLIENT_ID");
+if (!process.env.FLOW_ACCOUNT_CLIENT_SECRET) throw new Error("Require FLOW_ACCOUNT_CLIENT_SECRET");
+if (!process.env.FLOW_ACCOUNT_CLIENT_GRANT_TYPE) {
+  throw new Error("Require FLOW_ACCOUNT_CLIENT_GRANT_TYPE");
+}
+if (!process.env.FLOW_ACCOUNT_CLIENT_SCOPE) throw new Error("Require FLOW_ACCOUNT_CLIENT_SCOPE");
+
+const api = process.env.FLOW_ACCOUNT_URL;
+const clientId = process.env.FLOW_ACCOUNT_CLIENT_ID;
+const clientSecret = process.env.FLOW_ACCOUNT_CLIENT_SECRET;
+const clientGrantType = process.env.FLOW_ACCOUNT_CLIENT_GRANT_TYPE;
+const clientScope = process.env.FLOW_ACCOUNT_CLIENT_SCOPE;
+
+let token: string = "";
+let tokenExpire: number = Date.now();
+
+const flowaccount = {
+  auth: async () => {
+    // Get new token if it is expiring soon (30s).
+    if (token && Date.now() < tokenExpire + 30 * 1000) return { token, tokenExpire };
+
+    const payload = {
+      ["client_id"]: clientId,
+      ["client_secret"]: clientSecret,
+      ["grant_type"]: clientGrantType,
+      ["scope"]: clientScope,
+    };
+
+    const res = await fetch(api + "/token", {
+      method: "POST",
+      headers: {
+        ["Content-Type"]: "application/x-www-form-urlencoded",
+      },
+      body: new URLSearchParams(payload),
+    });
+
+    if (!res.ok) throw new Error("Cannot connect to flowaccount: " + (await res.text()));
+
+    const body: {
+      access_token: string;
+      expires_in: number;
+    } = await res.json();
+
+    token = body.access_token;
+    tokenExpire = Date.now() + body.expires_in * 1000;
+
+    return { token, tokenExpire };
+  },
+};
+
+export default flowaccount;