(C#) Office365 OAuth2 Access Token for SMTP, IMAP, POP

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Demonstrates how to get an OAuth2 access token for use in the SMTP, IMAP, and POP3 protocols.

Note: It is only the initial access token that must be obtained interactively using a browser (see the code and comments below). Once the initial OAuth2 access token is obtained, then it can refreshed indefinitely with no user interaction.

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

// -----------------------------------------------------------------------------------------------
// Important:  Setup your App Registration in Azure beforehand.  
// 
// See Create Azure App Registration for use with IMAP, POP3, and SMTP
// 
// Also, a detail that is often missed.  Make sure to specify "Web" for your Redirect URI.
// See Solution for Azure OAuth2 Error: Public clients can't send a client secret.
// -----------------------------------------------------------------------------------------------

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

// This should be the port in the localhost callback URL for your app.  
// The callback URL would look like "http://localhost:3017/" if the port number is 3017.
oauth2.ListenPort = 3017;

// Specify your OAuth2 authorization and token endpoints
// Replace "xxxxxxxxxx-71bf-4ebe-a866-738364321bf2" with your tenant ID, 
// or one of the following keywords: "common", "organizations", "consumers".
// 
// For more information about the /authorize endpoint, see Microsoft identity platform and OAuth 2.0 authorization code flow 

oauth2.AuthorizationEndpoint = "https://login.microsoftonline.com/xxxxxxxxxx-71bf-4ebe-a866-738364321bf2/oauth2/v2.0/authorize";
oauth2.TokenEndpoint = "https://login.microsoftonline.com/xxxxxxxxxx-71bf-4ebe-a866-738364321bf2/oauth2/v2.0/token";

// Replace these with actual values.
oauth2.ClientId = "CLIENT_ID";
oauth2.ClientSecret = "CLIENT_SECRET";

oauth2.CodeChallenge = false;

// Provide a SPACE separated list of scopes.
// Important: The offline_access scope is needed to get a refresh token.
oauth2.Scope = "openid profile offline_access https://outlook.office365.com/SMTP.Send https://outlook.office365.com/POP.AccessAsUser.All https://outlook.office365.com/IMAP.AccessAsUser.All";

// ----------------------------------------------------------------------
// Note: It is only the initial access token that must be obtained interactively using a browser.  
// Once the initial OAuth2 access token is obtained, then it can refreshed indefinitely with no user interaction.
// ----------------------------------------------------------------------

// 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;
}

// 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        
// The Microsoft 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...

// ----------------------------------------------------------------------
// Note: Read about how browser caching of credentials can cause problems.
// See OAuth2 Browser Caching Credentials
// ----------------------------------------------------------------------

// Now wait for the authorization.
// We'll wait for a max of 90 seconds.
int numMsWaited = 0;
while ((numMsWaited < 90000) && (oauth2.AuthFlowState < 3)) {
    oauth2.SleepMs(100);
    numMsWaited = numMsWaited + 100;
}

// If there was no response from the browser within 30 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;
}

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

// Get the full JSON response:
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.Load(oauth2.AccessTokenResponse);
json.EmitCompact = false;

// The JSON response looks like this:
// 
// {
//   "token_type": "Bearer",
//   "scope": "IMAP.AccessAsUser.All openid POP.AccessAsUser.All profile SMTP.Send email",
//   "expires_in": 3599,
//   "ext_expires_in": 3599,
//   "access_token": "...",
//   "refresh_token": "...",
//   "id_token": "...",
//   "expires_on": "1592748507"
// }

Debug.WriteLine(json.Emit());

// Save the JSON to a file for future requests.
Chilkat.FileAccess fac = new Chilkat.FileAccess();
fac.WriteEntireTextFile("qa_data/tokens/office365.json",json.Emit(),"utf-8",false);