React Native Requires Chilkat v10.1.2+
Dynamics CRM OAuth2 Access Token

Demonstrates how to get a Microsoft Dynamics CRM OAuth2 access token from a desktop (installed) application or script.
Chilkat React Native Downloads

React Native
import { CkDateTime, FileAccess, Http, JsonObject, OAuth2, StringBuilder } from '@chilkat/react-native'

async function chilkatExample() {
  let success = false;

  // To further clarify, see OAuth 2.0 Authorization Flow

  const oauth2 = new OAuth2();

  // This should be the port in the localhost redirect URL for your app.
  // Important: Make sure the redirect URI in your Azure app registration 
  // is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
  // The redirect URL would look like "http://localhost:3017/" if the port number is 3017.
  oauth2.listenPort = 3017;

  // Get the endpoints from the Azure Portal in the "endpoints" section of App Registrations..
  // The DYNAMICS-ENDPOINT-GUID is a Tenant dynamics-endpoint-guid  such as 1b54e7ee-d61b-4f12-a621-a6b2805b98c2
  oauth2.authorizationEndpoint = 'https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/authorize';
  oauth2.tokenEndpoint = 'https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token';

  // Replace these with actual values.
  oauth2.clientId = 'DYNAMICS-CRM-CLIENT-ID';
  oauth2.clientSecret = 'DYNAMICS-CRM-SECRET-KEY';

  oauth2.resource = 'https://mydynamicsdomain.api.crm.dynamics.com';

  oauth2.redirectAllowHtml = '<html><body><p>Thank you for granting access.</p></bod></html>';
  oauth2.redirectDenyHtml = '<html><body><p>Maybe next time...</p></bod></html>';

  // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
  let url: string;
  try {
    url = oauth2.startAuth();
  } catch {
    console.log(oauth2.lastErrorText);
    return;
  }

  // We can pre-check the URL by sending a GET to catch any up-front errors.
  // If we receive JSON with an error in response, then we don't proceed any farther.

  // If we receive an HTML response, and the response status = 200, then all should be OK.
  // We can proceed by displaying an interactive browser loaded with the url.
  const http = new Http();
  const sbPreCheck = new StringBuilder();
  success = true;
  try {
    await http.quickGetSbAsync(url, sbPreCheck);
  } catch {
    success = false;
  }
  if ((http.lastStatus !== 200) || (!sbPreCheck.startsWith('{', true))) {
    console.log('JSON Error Response:');
    console.log(sbPreCheck.getAsString());
    return;
  }

  // If the HTTP request itself failed, then examine the error.
  if (!success) {
    console.log(http.lastErrorText);
    return;
  }

  // OK.. the pre-flight check seems OK, go ahead with getting the interactive user authorization..

  // Launch the default browser on the system and navigate to the url.
  // The LaunchBrowser method was added in Chilkat v10.1.2.
  try {
    oauth2.launchBrowser(url);
  } catch {
    console.log(oauth2.lastErrorText);
    return;
  }

  // Wait for the user to approve or deny authorization in the browser.
  let numMsWaited = 0;
  while ((numMsWaited < 90000) && (oauth2.authFlowState < 3)) {
    oauth2.sleepMs(100);
    numMsWaited += 100;
  }

  // If the browser does not respond within the specified time, AuthFlowState will be:
  // 
  // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
  // 2: Waiting for Final Response – The thread is awaiting the final access token response.
  // In either case, cancel the background task initiated by StartAuth.

  if (oauth2.authFlowState < 3) {
    oauth2.cancel();
    console.log('No response from the browser!');
    return;
  }

  // Check AuthFlowState to determine if authorization was granted, denied, or failed:
  // 
  // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
  // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
  // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

  if (oauth2.authFlowState === 5) {
    console.log('OAuth2 failed to complete.');
    console.log(oauth2.failureInfo);
    return;
  }

  if (oauth2.authFlowState === 4) {
    console.log('OAuth2 authorization was denied.');
    console.log(oauth2.accessTokenResponse);
    return;
  }

  if (oauth2.authFlowState !== 3) {
    console.log(`Unexpected AuthFlowState:${oauth2.authFlowState}`);
    return;
  }

  console.log('OAuth2 authorization granted!');
  console.log(`Access Token = ${oauth2.accessToken}`);

  // Get the full JSON response:
  const json = new JsonObject();
  json.load(oauth2.accessTokenResponse);
  json.emitCompact = false;

  // The JSON response looks 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": "..."
  // }

  // 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 (!json.hasMember('expires_on')) {
    const dtExpire = new CkDateTime();
    dtExpire.setFromCurrentSystemTime();
    dtExpire.addSeconds(json.intOf('expires_in'));
    json.appendString('expires_on', dtExpire.getAsUnixTimeStr(false));
  }

  console.log(json.emit());

  // Save the JSON to a file for future requests.
  const fac = new FileAccess();
  fac.writeEntireTextFile('qa_data/tokens/dynamicsCrm.json', json.emit(), 'utf-8', false);
}