(Visual Basic 6.0) Google People API Refresh Access Token

Demonstrates how to refresh a Google Access Token for the Google People API.

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

' It is assumed we previously obtained an OAuth2 access token.
' This example loads the JSON access token file 
' saved by this example: Get Google People API OAuth2 Access Token

Dim jsonToken As New ChilkatJsonObject
Dim success As Long
success = jsonToken.LoadFile("qa_data/tokens/googlePeople.json")
If (success <> 1) Then
    Debug.Print "Failed to load googlePeople.json"
    Exit Sub
End If

' The access token JSON looks like this:

' {
'   "access_token": "ya29.a0AfH6S ... LAZYFUkf0",
'   "expires_in": 3599,
'   "refresh_token": "1//0fL_Ov ... ee0",
'   "scope": "https://www.googleapis.com/auth/contacts",
'   "token_type": "Bearer"
' }

Dim oauth2 As New ChilkatOAuth2

oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

' Replace these with actual values.
oauth2.ClientId = "GOOGLE-CLIENT-ID"
oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"

' Get the "refresh_token"
oauth2.RefreshToken = jsonToken.StringOf("refresh_token")

' Send the HTTP POST to refresh the access token..
success = oauth2.RefreshAccessToken()
If (success <> 1) Then
    Debug.Print oauth2.LastErrorText
    Exit Sub
End If

' The response contains a new access token, but we must keep
' our existing refresh token for when we need to refresh again in the future.
success = jsonToken.UpdateString("access_token",oauth2.AccessToken)

' Save the new JSON access token response to a file.
Dim sbJson As New ChilkatStringBuilder
jsonToken.EmitCompact = 0
success = jsonToken.EmitSb(sbJson)
success = sbJson.WriteFile("qa_data/tokens/googlePeople.json","utf-8",0)

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