Add Xero samples. Fixes googleworkspace#236.

Author: Eric Koleda

samples/Xero.gs

@@ -0,0 +1,98 @@
+/*
+ * This sample demonstrates how to configure the library for the Xero API.
+ * Instructions on how to generate OAuth2 credentuals is available here:
+ * https://developer.xero.com/documentation/oauth2/auth-flow
+ */
+
+var CLIENT_ID = '...';
+var CLIENT_SECRET = '...';
+
+/**
+ * Authorizes and makes a request to the Xero API.
+ */
+function run() {
+  var service = getService();
+  if (service.hasAccess()) {
+    // Retrieve the tenantId from storage.
+    var tenantId = service.getStorage().getValue('tenantId');
+    // Make a request to retrieve user information.
+    var url = 'https://api.xero.com/api.xro/2.0/Organisations';
+    var response = UrlFetchApp.fetch(url, {
+      headers: {
+        'Authorization': 'Bearer ' + service.getAccessToken(),
+        'Xero-tenant-id': tenantId
+      },
+    });
+    var result = JSON.parse(response.getContentText());
+    Logger.log(JSON.stringify(result, null, 2));
+  } else {
+    var authorizationUrl = service.getAuthorizationUrl();
+    Logger.log('Open the following URL and re-run the script: %s',
+        authorizationUrl);
+  }
+}
+
+/**
+ * Reset the authorization state, so that it can be re-tested.
+ */
+function reset() {
+  getService().reset();
+}
+
+/**
+ * Configures the service.
+ */
+function getService() {
+  return OAuth2.createService('Xero')
+    // Set the endpoint URLs.
+    .setAuthorizationBaseUrl(
+        'https://login.xero.com/identity/connect/authorize')
+    .setTokenUrl('https://identity.xero.com/connect/token')
+
+    // Set the client ID and secret.
+    .setClientId(CLIENT_ID)
+    .setClientSecret(CLIENT_SECRET)
+
+    // Set the name of the callback function that should be invoked to
+    // complete the OAuth flow.
+    .setCallbackFunction('authCallback')
+
+    // Set the property store where authorized tokens should be persisted.
+    .setPropertyStore(PropertiesService.getScriptProperties())
+
+    // Set the scopes to request from the user. The scope "offline_access" is
+    // required to refresh the token. The full list of scopes is available here:
+    // https://developer.xero.com/documentation/oauth2/scopes
+    .setScope('accounting.settings.read offline_access');
+};
+
+/**
+ * Handles the OAuth callback.
+ */
+function authCallback(request) {
+  var service = getService();
+  var authorized = service.handleCallback(request);
+  if (authorized) {
+    // Retrieve the connected tenants.
+    var response = UrlFetchApp.fetch('https://api.xero.com/connections', {
+      headers: {
+        Authorization: 'Bearer ' + service.getAccessToken()
+      },
+    });
+    var connections = JSON.parse(response.getContentText());
+    // Store the first tenant ID in the service's storage. If you want to
+    // support multiple tenants, store the full list and then let the user
+    // select which one to operate against.
+    service.getStorage().setValue('tenantId', connections[0].tenantId);
+    return HtmlService.createHtmlOutput('Success!');
+  } else {
+    return HtmlService.createHtmlOutput('Denied.');
+  }
+}
+
+/**
+ * Logs the redict URI to register in the Dropbox application settings.
+ */
+function logRedirectUri() {
+  Logger.log(OAuth2.getRedirectUri());
+}