(PureBasic) Get OAuth2 Access Token for Azure Registered App

Demonstrates how to get OAuth2 access token for an Azure Registered App from a desktop application or script. This example demonstrates the OAuth2 authorization flow.

This example requires Chilkat v10.1.2 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkFileAccess.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkOAuth2.pb"
IncludeFile "CkDateTime.pb"

Procedure ChilkatExample()

    ; To further clarify, see OAuth 2.0 Authorization Flow

    oauth2.i = CkOAuth2::ckCreate()
    If oauth2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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.
    CkOAuth2::setCkListenPort(oauth2, 3017)

    ; ----------------------------------------------------------------------------------------------------------
    ; The screenshot at the bottom of this page shows how we created the Azure App Registration for this example.
    ; ----------------------------------------------------------------------------------------------------------

    ; Note: The endpoint depends on the Azure App Registration.
    ; See How to Choose the Correct Endpoints for your Azure App Registration
    CkOAuth2::setCkAuthorizationEndpoint(oauth2, "https://login.microsoftonline.com/common/oauth2/v2.0/authorize")
    CkOAuth2::setCkTokenEndpoint(oauth2, "https://login.microsoftonline.com/common/oauth2/v2.0/token")

    ; Replace these with actual values.
    CkOAuth2::setCkClientId(oauth2, "CLIENT_ID")

    ; This is for Require Proof Key for Code Exchange (PKCE)
    ; See OAuth2 PKCE Explained
    CkOAuth2::setCkCodeChallenge(oauth2, 1)
    CkOAuth2::setCkCodeChallengeMethod(oauth2, "S256")

    ; Provide a SPACE separated list of scopes.
    ; See https://developer.microsoft.com/en-us/graph/docs/authorization/permission_scopes 

    ; Important: To get a refresh token in the final response, ask for "offline_access" scope
    CkOAuth2::setCkScope(oauth2, "openid profile offline_access user.readwrite mail.readwrite mail.send files.readwrite")

    ; Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    url.s = CkOAuth2::ckStartAuth(oauth2)
    If CkOAuth2::ckLastMethodSuccess(oauth2) <> 1
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    ; Launch the default browser on the system and navigate to the url.
    ; The LaunchBrowser method was added in Chilkat v10.1.2.
    success.i = CkOAuth2::ckLaunchBrowser(oauth2,url)
    If success = 0
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    ; Wait for the user to approve or deny authorization in the browser.
    numMsWaited.i = 0
    While (numMsWaited < 90000) AND (CkOAuth2::ckAuthFlowState(oauth2) < 3)
        CkOAuth2::ckSleepMs(oauth2,100)
        numMsWaited = numMsWaited + 100
    Wend

    ; 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 CkOAuth2::ckAuthFlowState(oauth2) < 3
        CkOAuth2::ckCancel(oauth2)
        Debug "No response from the browser!"
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    ; 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 CkOAuth2::ckAuthFlowState(oauth2) = 5
        Debug "OAuth2 failed to complete."
        Debug CkOAuth2::ckFailureInfo(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    If CkOAuth2::ckAuthFlowState(oauth2) = 4
        Debug "OAuth2 authorization was denied."
        Debug CkOAuth2::ckAccessTokenResponse(oauth2)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    If CkOAuth2::ckAuthFlowState(oauth2) <> 3
        Debug "Unexpected AuthFlowState:" + Str(CkOAuth2::ckAuthFlowState(oauth2))
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

    Debug "OAuth2 authorization granted!"
    Debug "Access Token = " + CkOAuth2::ckAccessToken(oauth2)

    ; When the token is near expiration, your app can refresh as shown here:
    ; Refresh Expiring OAuth2 Access Token for Azure Registered App

    ; Get the full JSON response:
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckLoad(json,CkOAuth2::ckAccessTokenResponse(oauth2))
    CkJsonObject::setCkEmitCompact(json, 0)

    ; The JSON response looks like this:

    ; {
    ;   "token_type": "Bearer",
    ;   "scope": "User.Read Mail.ReadWrite Mail.Send",
    ;   "expires_in": 3600,
    ;   "ext_expires_in": 0,
    ;   "access_token": "EwBAA8l6B...",
    ;   "refresh_token": "MCRMdbe...",
    ;   "id_token": "eyJ0eXA..."
    ; }

    ; If an "expires_on" member does not exist, then add the JSON member by
    ; getting the current system date/time and adding the "expires_in" seconds.
    ; This way we'll know when the token expires.
    If CkJsonObject::ckHasMember(json,"expires_on") <> 1
        dtExpire.i = CkDateTime::ckCreate()
        If dtExpire.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        CkDateTime::ckSetFromCurrentSystemTime(dtExpire)
        CkDateTime::ckAddSeconds(dtExpire,CkJsonObject::ckIntOf(json,"expires_in"))
        CkJsonObject::ckAppendString(json,"expires_on",CkDateTime::ckGetAsUnixTimeStr(dtExpire,0))
    EndIf

    Debug CkJsonObject::ckEmit(json)

    ; Save the JSON to a file for future requests.
    fac.i = CkFileAccess::ckCreate()
    If fac.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkFileAccess::ckWriteEntireTextFile(fac,"qa_data/tokens/_myAzureApp.json",CkJsonObject::ckEmit(json),"utf-8",0)

    ; This is a screenshot of how we created the Azure App for this example:
    ; 


    CkOAuth2::ckDispose(oauth2)
    CkJsonObject::ckDispose(json)
    CkDateTime::ckDispose(dtExpire)
    CkFileAccess::ckDispose(fac)


    ProcedureReturn
EndProcedure