(.NET Core C#) Quickbooks OAuth2 in a Desktop App

Demonstrates how to get a QuickBooks OAuth2 access token from a desktop application or script.

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

// ------------------------------------------------------------------------------------------------
// IMPORTANT: You first need to define an App in the Quickbooks Developer Dashboard.
// See How to Create an App in QuickBooks Developer Dashboard
// ------------------------------------------------------------------------------------------------

// This example is for desktop applicatons (it is not for code that runs on a web server).
// You'll need to add a line (or a few lines of code) to popup a web browser that navigates to a URL.
// This is explained in the comments below.

// This is the way to initially obtain the OAuth2 access token.  Afterwards it can be 
// repeatedly refreshed without user interaction, as shown in this example: Refresh Quickbooks OAuth2 Access Token.

Chilkat.OAuth2 oauth2 = new Chilkat.OAuth2();
bool success;

// QuickBooks OAuth2 allows for an "http://localhost:<portNumber>/" callback URL for sandbox testing,
// but not for production.
// For a desktop app, you must provide a script on your web server to redirect to "http://localhost/<portNumber>"
// It can be written in C#, PHP, or whatever desired.  It must include the query string in the redirection.
// For example, in PHP your script would look like this:

// <?php
//   header( 'Location: http://localhost:3017?' . $_SERVER['QUERY_STRING'] );
// ?>

oauth2.AppCallbackUrl = "https://yourwebserver.com/OAuth2.php";
oauth2.ListenPort = 3017;

oauth2.AuthorizationEndpoint = "https://appcenter.intuit.com/connect/oauth2";
oauth2.TokenEndpoint = "https://oauth.platform.intuit.com/oauth2/v1/tokens/bearer";

// Replace these with actual values.
oauth2.ClientId = "QUICKBOOKS-CLIENT-ID";
oauth2.ClientSecret = "QUICKBOOKS-CLIENT-SECRET";
oauth2.UseBasicAuth = true;
oauth2.CodeChallenge = false;

// Indicate the desired access.  Possible scopes that can appear in the list are:
// com.intuit.quickbooks.accounting:  QuickBooks Online API
// com.intuit.quickbooks.payment:  QuickBooks Payments API
// openid:  OpenID Connect processing
// profile:  user's given and family names
// email:  user's email address
// phone:  user's phone number
// address:  user's physical address
oauth2.Scope = "com.intuit.quickbooks.accounting";

// Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
string url = oauth2.StartAuth();
if (oauth2.LastMethodSuccess != true) {
    Debug.WriteLine(oauth2.LastErrorText);
    return;
}

Debug.WriteLine("url = " + url);

// At this point, your application should load the URL in a browser.
// For example, 
// in C#: System.Diagnostics.Process.Start(url);
// in Java: Desktop.getDesktop().browse(new URI(url));
// in VBScript: Set wsh=WScript.CreateObject("WScript.Shell")
//              wsh.Run url
// in Xojo: ShowURL(url)  (see http://docs.xojo.com/index.php/ShowURL)
// in Dataflex: Runprogram Background "c:\Program Files\Internet Explorer\iexplore.exe" sUrl
// in dBASE: run(false, 'rundll32 url.dll,FileProtocolHandler "' + lcUrl + '"')
// The QuickBooks account owner would interactively accept or deny the authorization request.

// Add the code to load the url in a web browser here...
// Add the code to load the url in a web browser here...
// Add the code to load the url in a web browser here...

// Now wait for the authorization.
// We'll wait for a max of 60 seconds.
int numMsWaited = 0;
while ((numMsWaited < 60000) && (oauth2.AuthFlowState < 3)) {
    oauth2.SleepMs(100);
    numMsWaited = numMsWaited + 100;
}

// If there was no response from the browser within 60 seconds, then 
// the AuthFlowState will be equal to 1 or 2.
// 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
// 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
// In that case, cancel the background task started in the call to StartAuth.
if (oauth2.AuthFlowState < 3) {
    oauth2.Cancel();
    Debug.WriteLine("No response from the browser!");
    return;
}

// Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
// The possible AuthFlowState values are:
// 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
// 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
// 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
if (oauth2.AuthFlowState == 5) {
    Debug.WriteLine("OAuth2 failed to complete.");
    Debug.WriteLine(oauth2.FailureInfo);
    return;
}

if (oauth2.AuthFlowState == 4) {
    Debug.WriteLine("OAuth2 authorization was denied.");
    Debug.WriteLine(oauth2.AccessTokenResponse);
    return;
}

if (oauth2.AuthFlowState != 3) {
    Debug.WriteLine("Unexpected AuthFlowState:" + Convert.ToString(oauth2.AuthFlowState));
    return;
}

// Save the full JSON access token response to a file.
Chilkat.StringBuilder sbJson = new Chilkat.StringBuilder();
sbJson.Append(oauth2.AccessTokenResponse);
sbJson.WriteFile("qa_data/tokens/qb-access-token.json","utf-8",false);

// The full JSON received looks like this:
// {
//   "expires_in": 3600,
//   "x_refresh_token_expires_in": 8726400,
//   "refresh_token": "L011546037639r ... 3vR2DrbOmg0Sdagw",
//   "access_token": "eyJlbmMiOiJBMTI4Q0 ... oETJEMbeggg",
//   "token_type": "bearer"
// }

Debug.WriteLine("OAuth2 authorization granted!");
Debug.WriteLine("Access Token = " + oauth2.AccessToken);