(Node.js) Refresh HMRC OAuth2 Access Token

Demonstrates how to refresh an HMRC access token.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // See Get HMRC Access Token 
    // for sample code showing how to obtain a HMRC access token for desktop apps.

    // It is assumed we previously obtained an OAuth2 access token for HMRC.

    var jsonToken = new chilkat.JsonObject();
    var success = jsonToken.LoadFile("qa_data/tokens/hmrc.json");
    if (success !== true) {
        console.log("Failed to load hmrc.json");
        return;
    }

    // The access token JSON looks something like this:

    // {
    //   "token_type": "Bearer",
    //   "scope": "user_impersonation",
    //   "expires_in": "3599",
    //   "ext_expires_in": "0",
    //   "expires_on": "1524783438",
    //   "not_before": "1524779538",
    //   "resource": "https://mydomain.api.crm.dynamics.com",
    //   "access_token": "...",
    //   "refresh_token": "...",
    //   "id_token": "..."
    // }

    var oauth2 = new chilkat.OAuth2();

    oauth2.TokenEndpoint = "https://test-api.service.hmrc.gov.uk/oauth/token";

    // Replace these with actual values.
    oauth2.ClientId = "HMRC-CLIENT-ID";
    oauth2.ClientSecret = "HMRC-CLIENT-SECRET";

    // Get the "refresh_token"
    oauth2.RefreshToken = jsonToken.StringOf("refresh_token");

    // Send the HTTP POST to refresh the access token..
    success = oauth2.RefreshAccessToken();
    if (success !== true) {
        console.log(oauth2.LastErrorText);
        return;
    }

    // Load the access token response into the json object 
    jsonToken.Load(oauth2.AccessTokenResponse);

    // If an "expires_on" member does not exist, then add the JSON member by
    // getting the current system date/time and adding the "expires_in" seconds.
    // This way we'll know when the token expires.
    if (jsonToken.HasMember("expires_on") == false) {
        var dtExpire = new chilkat.CkDateTime();
        dtExpire.SetFromCurrentSystemTime();
        dtExpire.AddSeconds(jsonToken.IntOf("expires_in"));
        jsonToken.AppendString("expires_on",dtExpire.GetAsUnixTimeStr(false));
    }

    // Save the new JSON access token response to a file.
    // The access + refresh tokens contained in this JSON will be needed for the next refresh.
    var sbJson = new chilkat.StringBuilder();
    jsonToken.EmitCompact = false;
    jsonToken.EmitSb(sbJson);
    sbJson.WriteFile("qa_data/tokens/hmrc.json","utf-8",false);

    console.log("OAuth2 authorization granted!");
    console.log("New Access Token = " + oauth2.AccessToken);

}

chilkatExample();