(Visual Basic 6.0) 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.
' -----------------------------------------------------------------------------------------------

Dim oauth2 As New ChilkatOAuth2
Dim success As Long

' 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 = 0

' 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.
Dim url As String
url = oauth2.StartAuth()
If (oauth2.LastMethodSuccess <> 1) Then
    Debug.Print oauth2.LastErrorText
    Exit Sub
End If

' 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.
Dim numMsWaited As Long
numMsWaited = 0
Do While (numMsWaited < 90000) And (oauth2.AuthFlowState < 3)
    oauth2.SleepMs 100
    numMsWaited = numMsWaited + 100
Loop

' 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) Then
    success = oauth2.Cancel()
    Debug.Print "No response from the browser!"
    Exit Sub
End If

' 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) Then
    Debug.Print "OAuth2 failed to complete."
    Debug.Print oauth2.FailureInfo
    Exit Sub
End If

If (oauth2.AuthFlowState = 4) Then
    Debug.Print "OAuth2 authorization was denied."
    Debug.Print oauth2.AccessTokenResponse
    Exit Sub
End If

If (oauth2.AuthFlowState <> 3) Then
    Debug.Print "Unexpected AuthFlowState:" & oauth2.AuthFlowState
    Exit Sub
End If

Debug.Print "OAuth2 authorization granted!"
Debug.Print "Access Token = " & oauth2.AccessToken

' Get the full JSON response:
Dim json As New ChilkatJsonObject
success = json.Load(oauth2.AccessTokenResponse)
json.EmitCompact = 0

' 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.Print json.Emit()

' Save the JSON to a file for future requests.
Dim fac As New CkFileAccess
success = fac.WriteEntireTextFile("qa_data/tokens/office365.json",json.Emit(),"utf-8",0)