(Unicode C++) Automatically Refresh Token for 401 Unauthorized

Demonstrates how to automatically refresh an access token (without user interaction) when the token expires and a 401 Unauthorized response is received.

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#include <CkJsonObjectW.h>
#include <CkHttpW.h>
#include <CkOAuth2W.h>
#include <CkStringBuilderW.h>

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

    const wchar_t *tokenFilePath = L"qa_data/tokens/googleCalendar.json";

    // Get our current access token.
    CkJsonObjectW jsonToken;
    bool success = jsonToken.LoadFile(tokenFilePath);
    if (jsonToken.HasMember(L"access_token") == false) {
        wprintf(L"No access token found.\n");
        return;
    }

    CkHttpW http;
    http.put_AuthToken(jsonToken.stringOf(L"access_token"));

    const wchar_t *jsonResponse = http.quickGetStr(L"https://www.googleapis.com/calendar/v3/users/me/calendarList");
    if (http.get_LastMethodSuccess() != true) {

        if (http.get_LastStatus() != 401) {
            wprintf(L"%s\n",http.lastErrorText());
            wprintf(L"----\n");
            wprintf(L"%s\n",http.lastResponseBody());
            return;
        }

        // The access token must've expired. 
        // Refresh the access token and then retry the request.
        CkOAuth2W oauth2;

        oauth2.put_TokenEndpoint(L"https://www.googleapis.com/oauth2/v4/token");

        // Replace these with actual values.
        oauth2.put_ClientId(L"GOOGLE-CLIENT-ID");
        oauth2.put_ClientSecret(L"GOOGLE-CLIENT-SECRET");

        // Get the "refresh_token"
        oauth2.put_RefreshToken(jsonToken.stringOf(L"refresh_token"));

        // Send the HTTP POST to refresh the access token..
        success = oauth2.RefreshAccessToken();
        if (success != true) {
            wprintf(L"%s\n",oauth2.lastErrorText());
            return;
        }

        // 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.
        jsonToken.UpdateString(L"access_token",oauth2.accessToken());

        // Save the new JSON access token response to a file.
        CkStringBuilderW sbJson;
        jsonToken.put_EmitCompact(false);
        jsonToken.EmitSb(sbJson);
        sbJson.WriteFile(tokenFilePath,L"utf-8",false);

        wprintf(L"OAuth2 authorization granted!\n");
        wprintf(L"New Access Token = %s\n",oauth2.accessToken());

        // re-try the original request.
        http.put_AuthToken(oauth2.accessToken());
        jsonResponse = http.quickGetStr(L"https://www.googleapis.com/calendar/v3/users/me/calendarList");
        if (http.get_LastMethodSuccess() != true) {
            wprintf(L"%s\n",http.lastErrorText());
            return;
        }

    }

    wprintf(L"%s\n",jsonResponse);
    wprintf(L"-----------------------------\n");
    }