(PureBasic) Refresh Expiring OAuth2 Access Token for Azure Registered App

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Chilkat PureBasic Module Download Chilkat PureBasic Module

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

Procedure ChilkatExample()

    ; We previously obtained an access token and saved the JSON to a file using this example:
    ; Get OAuth2 Access Token for Azure Registered App

    ; This example will examine the JSON and expiration date, and if near expiration will
    ; refresh the access token.

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

    success.i = CkJsonObject::ckLoadFile(json,"qa_data/tokens/_myAzureApp.json")
    If success <> 1
        Debug "Failed to load the access token."
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    ; The contents of the JSON look like this:
    ; {
    ;   "token_type": "Bearer",
    ;   "scope": "User.Read Mail.ReadWrite Mail.Send",
    ;   "expires_in": 3600,
    ;   "ext_expires_in": 0,
    ;   "access_token": "EwBAA8l6B...",
    ;   "refresh_token": "MCRMdbe6Cd...",
    ;   "id_token": "eyJ0eXAiOiJ...",
    ;   "expires_on": "1494112119"
    ; }

    ; The "expires_on" value is a Unix time.
    dtExpire.i = CkDateTime::ckCreate()
    If dtExpire.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkDateTime::ckSetFromUnixTime(dtExpire,0,CkJsonObject::ckIntOf(json,"expires_on"))

    ; If this date/time expires within 10 minutes of the current system time, refresh the token.
    If CkDateTime::ckExpiresWithin(dtExpire,10,"minutes") <> 1
        Debug "No need to refresh, the access token won't expire within the next 10 minutes."
        CkJsonObject::ckDispose(json)
        CkDateTime::ckDispose(dtExpire)
        ProcedureReturn
    EndIf

    ; OK, we need to refresh the access token..
    oauth2.i = CkOAuth2::ckCreate()
    If oauth2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

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

    ; Use your client ID.
    CkOAuth2::setCkClientId(oauth2, "CLIENT_ID")

    ; Get the existing refresh token.
    CkOAuth2::setCkRefreshToken(oauth2, CkJsonObject::ckStringOf(json,"refresh_token"))

    ; Send the HTTP POST to refresh the access token.
    success = CkOAuth2::ckRefreshAccessToken(oauth2)
    If success = 0
        Debug CkOAuth2::ckLastErrorText(oauth2)
        CkJsonObject::ckDispose(json)
        CkDateTime::ckDispose(dtExpire)
        CkOAuth2::ckDispose(oauth2)
        ProcedureReturn
    EndIf

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

    ; Get the full JSON response:
    CkJsonObject::ckLoad(json,CkOAuth2::ckAccessTokenResponse(oauth2))
    CkJsonObject::setCkEmitCompact(json, 0)

    ; 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
        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 new access token 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)


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


    ProcedureReturn
EndProcedure