Add nxapi-powered NSO client

.env.example

@@ -1,3 +1,9 @@
+# Nintendo API
+NINTENDO_TOKEN=
+
+# User agent string
+USER_AGENT=
+
 # Twitter API parameters
 TWITTER_CONSUMER_KEY=
 TWITTER_CONSUMER_SECRET=

app/common/ValueCache.mjs

@@ -0,0 +1,45 @@
+import fs from 'fs/promises';
+
+export default class ValueCache
+{
+  constructor(key) {
+    this._key = key;
+  }
+
+  get path() {
+    return `storage/${this._key}.json`;
+  }
+
+  async _getRawItem() {
+    try {
+      let data = await fs.readFile(this.path);
+
+      return JSON.parse(data);
+    } catch (e) {
+      return null;
+    }
+  }
+
+  async get() {
+    let item = await this._getRawItem();
+
+    // If the cached value is already expired, return null
+    if (item && item.expires && item.expires < new Date) {
+      return null;
+    }
+
+    return item;
+  }
+
+  async getData() {
+    let item = await this.get();
+
+    return item && item.data;
+  }
+
+  async setData(data, expires = null) {
+    let serialized = JSON.stringify({ expires, data }, undefined, 2);
+
+    await fs.writeFile(this.path, serialized);
+  }
+}

app/nso/NsoClient.mjs

@@ -0,0 +1,75 @@
+import CoralApi from 'nxapi/coral';
+import { addUserAgent } from "nxapi";
+import ValueCache from '../common/ValueCache.mjs';
+
+let _nxapiInitialized = false;
+
+function initializeNxapi() {
+  if (!_nxapiInitialized) {
+    addUserAgent(process.env.USER_AGENT);
+  }
+
+  _nxapiInitialized = true;
+}
+
+export default class NsoClient
+{
+  constructor(nintendoToken = null) {
+    initializeNxapi();
+
+    this.nintendoToken = nintendoToken || process.env.NINTENDO_TOKEN;
+    this.coralCache = new ValueCache('coral');
+  }
+
+  _calculateCacheExpiry(expiresIn) {
+    let expires = Date.now() + expiresIn * 1000;
+
+    // Expire 5min early to make sure we have time to execute requests
+    return expires - 5 * 60 * 1000;
+  }
+
+  async getCoralApi() {
+    let data = await this.coralCache.getData();
+
+    if (!data) {
+      data = await this._createCoralSession();
+    }
+
+    return CoralApi.createWithSavedToken(data);
+  }
+
+  async _createCoralSession() {
+    console.debug('Creating Coral session');
+    let { data } = await CoralApi.createWithSessionToken(this.nintendoToken);
+
+    let expires = this._calculateCacheExpiry(data.credential.expiresIn);
+    console.debug(`Caching Coral session until: ${expires}`);
+    await this.coralCache.setData(data, expires);
+
+    return data;
+  }
+
+  async getWebServiceToken(id) {
+    let tokenCache = new ValueCache(`webservicetoken.${id}`);
+    let token = await tokenCache.getData();
+
+    if (!token) {
+      token = await this._createWebServiceToken(id, tokenCache);
+    }
+
+    return token.accessToken;
+  }
+
+  async _createWebServiceToken(id, tokenCache) {
+    let coral = await this.getCoralApi();
+
+    console.debug(`Creating web service token for ID ${id}`);
+    let { result } = await coral.getWebServiceToken(id);
+
+    let expires = this._calculateCacheExpiry(result.expiresIn);
+    console.debug(`Caching web service token for ID ${id} until: ${expires}`);
+    await tokenCache.setData(result, expires);
+
+    return result;
+  }
+}