(Visual FoxPro) Azure AD Service-to-service access token request

Send an Azure AD service-to-service token request to get an access token using a shared secret.

For more information, see https://docs.microsoft.com/en-us/azure/active-directory/develop/v1-oauth2-client-creds-grant-flow#service-to-service-access-token-request

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loHttp
LOCAL loReq
LOCAL loResp
LOCAL lnRespStatusCode
LOCAL loJson
LOCAL lcToken_type
LOCAL lcExpires_in
LOCAL lcExt_expires_in
LOCAL lcExpires_on
LOCAL lcNot_before
LOCAL lcResource
LOCAL lcAccess_token

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')

* To see the exact HTTP request sent and the response, set the SessionLogFilename property:
loHttp.SessionLogFilename = "qa_output/chilkatHttpLog.txt"

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.HttpRequest')
loReq = CreateObject('Chilkat.HttpRequest')

* Set the following request params:
* grant_type 	required 	Specifies the requested grant type. In a Client Credentials Grant flow, the value must be client_credentials.
* 
* client_id 	required 	Specifies the Azure AD client id of the calling web service. 
*     To find the calling application's client ID, in the Azure portal, click Azure Active Directory, click App registrations, click the application. 
*     The client_id is the Application ID
* 
* client_secret 	required 	Enter a key registered for the calling web service or daemon application in Azure AD. 
*     To create a key, in the Azure portal, click Azure Active Directory, click App registrations, click the application, click Settings, click Keys, and add a Key.
*     URL-encode this secret when providing it.
* 
* resource 	required 	Enter the App ID URI of the receiving web service. To find the App ID URI, in the Azure portal, click Azure Active Directory, 
*     click App registrations, click the service application, and then click Settings and Properties.

loReq.AddParam("grant_type","client_credentials")
loReq.AddParam("client_id","MY_CLIENT_ID")
loReq.AddParam("client_secret","MY_CLIENT_SECRET")
loReq.AddParam("resource","https://service.contoso.com/")

* The URL passed to PostUrlEncoded has this form:   https://login.microsoftonline.com/<tenant_id>/oauth2/token
loResp = loHttp.PostUrlEncoded("https://login.microsoftonline.com/<tenant_id>/oauth2/token",loReq)
IF (loHttp.LastMethodSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loHttp
    RELEASE loReq
    CANCEL
ENDIF

lnRespStatusCode = loResp.StatusCode
? "Response Status Code = " + STR(lnRespStatusCode)

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
loJson.EmitCompact = 0
loJson.Load(loResp.BodyStr)
? "Response JSON:"
? loJson.Emit()

IF (lnRespStatusCode >= 400) THEN
    ? "Response Header:"
    ? loResp.Header
    ? "Failed."
    RELEASE loResp
    RELEASE loHttp
    RELEASE loReq
    RELEASE loJson
    CANCEL
ENDIF

* Sample response:

* {
*   "token_type": "Bearer",
*   "expires_in": "3599",
*   "ext_expires_in": "3599",
*   "expires_on": "1570059833",
*   "not_before": "1570055933",
*   "resource": "https://adminchilkatsoft.onmicrosoft.com/eb1b8ced-76b7-4845-aec5-d3e91776e345",
*   "access_token": "eyJ0eXAiO ... pmgw"
* }

* To get the items from the JSON....
lcToken_type = loJson.StringOf("token_type")
lcExpires_in = loJson.StringOf("expires_in")
lcExt_expires_in = loJson.StringOf("ext_expires_in")
lcExpires_on = loJson.StringOf("expires_on")
lcNot_before = loJson.StringOf("not_before")
lcResource = loJson.StringOf("resource")
lcAccess_token = loJson.StringOf("access_token")

RELEASE loResp

RELEASE loHttp
RELEASE loReq
RELEASE loJson