(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 <C_CkJsonObject.h>
#include <C_CkHttp.h>
#include <C_CkOAuth2.h>
#include <C_CkStringBuilder.h>

void ChilkatSample(void)
    {
    const char *tokenFilePath;
    HCkJsonObject jsonToken;
    BOOL success;
    HCkHttp http;
    const char *jsonResponse;
    HCkOAuth2 oauth2;
    HCkStringBuilder sbJson;

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

    tokenFilePath = "qa_data/tokens/googleCalendar.json";

    // Get our current access token.
    jsonToken = CkJsonObject_Create();
    success = CkJsonObject_LoadFile(jsonToken,tokenFilePath);
    if (CkJsonObject_HasMember(jsonToken,"access_token") == FALSE) {
        printf("No access token found.\n");
        CkJsonObject_Dispose(jsonToken);
        return;
    }

    http = CkHttp_Create();
    CkHttp_putAuthToken(http,CkJsonObject_stringOf(jsonToken,"access_token"));

    jsonResponse = CkHttp_quickGetStr(http,"https://www.googleapis.com/calendar/v3/users/me/calendarList");
    if (CkHttp_getLastMethodSuccess(http) != TRUE) {

        if (CkHttp_getLastStatus(http) != 401) {
            printf("%s\n",CkHttp_lastErrorText(http));
            printf("----\n");
            printf("%s\n",CkHttp_lastResponseBody(http));
            CkJsonObject_Dispose(jsonToken);
            CkHttp_Dispose(http);
            return;
        }

        // The access token must've expired. 
        // Refresh the access token and then retry the request.
        oauth2 = CkOAuth2_Create();

        CkOAuth2_putTokenEndpoint(oauth2,"https://www.googleapis.com/oauth2/v4/token");

        // Replace these with actual values.
        CkOAuth2_putClientId(oauth2,"GOOGLE-CLIENT-ID");
        CkOAuth2_putClientSecret(oauth2,"GOOGLE-CLIENT-SECRET");

        // Get the "refresh_token"
        CkOAuth2_putRefreshToken(oauth2,CkJsonObject_stringOf(jsonToken,"refresh_token"));

        // Send the HTTP POST to refresh the access token..
        success = CkOAuth2_RefreshAccessToken(oauth2);
        if (success != TRUE) {
            printf("%s\n",CkOAuth2_lastErrorText(oauth2));
            CkJsonObject_Dispose(jsonToken);
            CkHttp_Dispose(http);
            CkOAuth2_Dispose(oauth2);
            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.
        CkJsonObject_UpdateString(jsonToken,"access_token",CkOAuth2_accessToken(oauth2));

        // Save the new JSON access token response to a file.
        sbJson = CkStringBuilder_Create();
        CkJsonObject_putEmitCompact(jsonToken,FALSE);
        CkJsonObject_EmitSb(jsonToken,sbJson);
        CkStringBuilder_WriteFile(sbJson,tokenFilePath,"utf-8",FALSE);

        printf("OAuth2 authorization granted!\n");
        printf("New Access Token = %s\n",CkOAuth2_accessToken(oauth2));

        // re-try the original request.
        CkHttp_putAuthToken(http,CkOAuth2_accessToken(oauth2));
        jsonResponse = CkHttp_quickGetStr(http,"https://www.googleapis.com/calendar/v3/users/me/calendarList");
        if (CkHttp_getLastMethodSuccess(http) != TRUE) {
            printf("%s\n",CkHttp_lastErrorText(http));
            CkJsonObject_Dispose(jsonToken);
            CkHttp_Dispose(http);
            CkOAuth2_Dispose(oauth2);
            CkStringBuilder_Dispose(sbJson);
            return;
        }

    }

    printf("%s\n",jsonResponse);
    printf("-----------------------------\n");


    CkJsonObject_Dispose(jsonToken);
    CkHttp_Dispose(http);
    CkOAuth2_Dispose(oauth2);
    CkStringBuilder_Dispose(sbJson);

    }