(VB.NET) Yahoo Mail OAuth2 Access Token for Desktop App

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Note: This example requires Chilkat v10.1.2 or greater.

For more information, see https://developer.yahoo.com/oauth2/guide/

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' First, you must define your app in Yahoo Developer (https://developer.yahoo.com/apps/) like this:

' 

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

Dim oauth2 As New Chilkat.OAuth2

' Your applicaton must use your own public web server as an intermediate
' to receive and forward the redirect to localhost.
' See Using Your Web Server as an Intermediary for OAuth2 Redirect to localhost
oauth2.AppCallbackUrl = "https://yourwebserver.com/oauth_redirect"
oauth2.ListenPort = 3017

oauth2.AuthorizationEndpoint = "https://api.login.yahoo.com/oauth2/request_auth"
oauth2.TokenEndpoint = "https://api.login.yahoo.com/oauth2/get_token"

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

' Do not send the "scope" query param for Yahoo OAuth2.
oauth2.UncommonOptions = "NO_OAUTH2_SCOPE"

' Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
Dim url As String = oauth2.StartAuth()
If (oauth2.LastMethodSuccess <> True) Then
    Debug.WriteLine(oauth2.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("url = " & url)

' Launch the default browser on the system and navigate to the url.
' The LaunchBrowser method was added in Chilkat v10.1.2.
Dim success As Boolean = oauth2.LaunchBrowser(url)
If (success = False) Then
    Debug.WriteLine(oauth2.LastErrorText)
    Exit Sub
End If


' Wait for the user to approve or deny authorization in the browser.
Dim numMsWaited As Integer = 0
While (numMsWaited < 90000) And (oauth2.AuthFlowState < 3)
    oauth2.SleepMs(100)
    numMsWaited = numMsWaited + 100
End While

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


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


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


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


' Save the full JSON access token response to a file.
Dim sbJson As New Chilkat.StringBuilder
sbJson.Append(oauth2.AccessTokenResponse)
sbJson.WriteFile("qa_data/tokens/yahooMail.json","utf-8",False)

' The saved JSON response looks like this:

' {
'   "access_token": "kCVQdnOdul...LHucA--",
'   "refresh_token": "AIenVXETSo0jklFBVkPS8vVm8E.Ej9ToRG.xDbDYmZ65WIs5t6CZhDrD",
'   "expires_in": 3600,
'   "token_type": "bearer",
'   "xoauth_yahoo_guid": "HGDQCVF5JB4YDOWHITQJFBHCWA"
' }

Debug.WriteLine("OAuth2 authorization granted!")
Debug.WriteLine("Access Token: " & oauth2.AccessToken)