(Unicode C) Refresh Access Token on 401 Unauthorized and Retry (Service Account)

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Demonstrates how to handle an expired access token error, refresh the token, and retry the request. (In this case, the request is to download an object from Google Cloud Storage.)

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#include <C_CkStringBuilderW.h>
#include <C_CkHttpW.h>
#include <C_CkBinDataW.h>
#include <C_CkFileAccessW.h>
#include <C_CkAuthGoogleW.h>
#include <C_CkSocketW.h>

void ChilkatSample(void)
    {
    HCkStringBuilderW sbToken;
    BOOL success;
    HCkHttpW http;
    const wchar_t *url;
    HCkBinDataW fileData;
    int responseCode;
    HCkFileAccessW fac;
    const wchar_t *jsonKey;
    HCkAuthGoogleW gAuth;
    HCkSocketW tlsSock;
    HCkStringBuilderW sbErrorResponse;

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

    // This example uses a previously obtained access token having permission for the 
    // scope "https://www.googleapis.com/auth/cloud-platform"

    // In this example, Get Google Cloud Storage OAuth2 Access Token, 
    // the service account access token was saved to a text file.  This example fetches the access token from the file..
    sbToken = CkStringBuilderW_Create();
    success = CkStringBuilderW_LoadFile(sbToken,L"qa_data/tokens/googleCloudStorageAccessToken.txt",L"utf-8");
    if (success == FALSE) {
        wprintf(L"Failed to load access token.\n");
        CkStringBuilderW_Dispose(sbToken);
        return;
    }

    http = CkHttpW_Create();

    CkHttpW_putAuthToken(http,CkStringBuilderW_getAsString(sbToken));

    // Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
    CkHttpW_SetUrlVar(http,L"bucket_name",L"chilkat-ocean");
    CkHttpW_SetUrlVar(http,L"object_name",L"starfish.jpg");
    url = L"https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media";

    // If there is an error response, then we didn't actually download the file data,
    // but instead we downloaded an error response..
    fileData = CkBinDataW_Create();
    success = CkHttpW_DownloadBd(http,url,fileData);
    responseCode = CkHttpW_getLastStatus(http);
    if ((success == FALSE) && (responseCode != 401)) {
        wprintf(L"%s\n",CkHttpW_lastErrorText(http));
        CkStringBuilderW_Dispose(sbToken);
        CkHttpW_Dispose(http);
        CkBinDataW_Dispose(fileData);
        return;
    }

    if (responseCode == 401) {
        wprintf(L"Received 401 Unauthorized response. Attempting to refresh the access token...\n");

        // May be that the access token expired.
        // Load our JSON key and request a new access token, then retry the original request.
        fac = CkFileAccessW_Create();
        jsonKey = CkFileAccessW_readEntireTextFile(fac,L"qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json",L"utf-8");
        if (CkFileAccessW_getLastMethodSuccess(fac) != TRUE) {
            wprintf(L"%s\n",CkFileAccessW_lastErrorText(fac));
            CkStringBuilderW_Dispose(sbToken);
            CkHttpW_Dispose(http);
            CkBinDataW_Dispose(fileData);
            CkFileAccessW_Dispose(fac);
            return;
        }

        gAuth = CkAuthGoogleW_Create();
        CkAuthGoogleW_putJsonKey(gAuth,jsonKey);
        CkAuthGoogleW_putScope(gAuth,L"https://www.googleapis.com/auth/cloud-platform");
        CkAuthGoogleW_putExpireNumSeconds(gAuth,3600);
        CkAuthGoogleW_putSubEmailAddress(gAuth,L"");

        tlsSock = CkSocketW_Create();
        success = CkSocketW_Connect(tlsSock,L"www.googleapis.com",443,TRUE,5000);
        if (success != TRUE) {
            wprintf(L"%s\n",CkSocketW_lastErrorText(tlsSock));
            CkStringBuilderW_Dispose(sbToken);
            CkHttpW_Dispose(http);
            CkBinDataW_Dispose(fileData);
            CkFileAccessW_Dispose(fac);
            CkAuthGoogleW_Dispose(gAuth);
            CkSocketW_Dispose(tlsSock);
            return;
        }

        success = CkAuthGoogleW_ObtainAccessToken(gAuth,tlsSock);
        if (success != TRUE) {
            wprintf(L"%s\n",CkAuthGoogleW_lastErrorText(gAuth));
            CkStringBuilderW_Dispose(sbToken);
            CkHttpW_Dispose(http);
            CkBinDataW_Dispose(fileData);
            CkFileAccessW_Dispose(fac);
            CkAuthGoogleW_Dispose(gAuth);
            CkSocketW_Dispose(tlsSock);
            return;
        }

        CkFileAccessW_WriteEntireTextFile(fac,L"qa_data/tokens/googleCloudStorageAccessToken.txt",CkAuthGoogleW_accessToken(gAuth),L"utf-8",FALSE);

        // Retry the original request.
        CkHttpW_putAuthToken(http,CkAuthGoogleW_accessToken(gAuth));
        success = CkHttpW_DownloadBd(http,url,fileData);
        if (success == FALSE) {
            wprintf(L"%s\n",CkHttpW_lastErrorText(http));
            CkStringBuilderW_Dispose(sbToken);
            CkHttpW_Dispose(http);
            CkBinDataW_Dispose(fileData);
            CkFileAccessW_Dispose(fac);
            CkAuthGoogleW_Dispose(gAuth);
            CkSocketW_Dispose(tlsSock);
            return;
        }

    }

    if (responseCode != 200) {
        // Get the error response
        sbErrorResponse = CkStringBuilderW_Create();
        CkStringBuilderW_AppendBd(sbErrorResponse,fileData,L"utf-8",0,0);
        wprintf(L"Error response code = %d\n",responseCode);
        wprintf(L"Error:\n");
        wprintf(L"%s\n",CkStringBuilderW_getAsString(sbErrorResponse));
        CkStringBuilderW_Dispose(sbToken);
        CkHttpW_Dispose(http);
        CkBinDataW_Dispose(fileData);
        CkFileAccessW_Dispose(fac);
        CkAuthGoogleW_Dispose(gAuth);
        CkSocketW_Dispose(tlsSock);
        CkStringBuilderW_Dispose(sbErrorResponse);
        return;
    }

    wprintf(L"Success.\n");

    // Save the downloaded data to a file.
    success = CkBinDataW_WriteFile(fileData,L"qa_output/starfish.jpg");


    CkStringBuilderW_Dispose(sbToken);
    CkHttpW_Dispose(http);
    CkBinDataW_Dispose(fileData);
    CkFileAccessW_Dispose(fac);
    CkAuthGoogleW_Dispose(gAuth);
    CkSocketW_Dispose(tlsSock);
    CkStringBuilderW_Dispose(sbErrorResponse);

    }