(C) Google Drive Refresh Access Token

Demonstrates how to automatically refresh the access token when it expires.

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#include <C_CkJsonObject.h>
#include <C_CkOAuth2.h>
#include <C_CkFileAccess.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkJsonObject json;
    const char *tokenFilePath;
    HCkOAuth2 oauth2;
    HCkFileAccess fac;

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

    success = TRUE;

    // This example uses a previously obtained access token having permission for the 
    // Google Drive scope.

    // The access token (and refresh token) was previously saved to a JSON file with this format:
    // See Get Google Drive OAuth2 Access Token

    // {
    //   "access_token": "ya29.Gls-BsdxTWuenChv ... yzVIrXikkLxu5T6dy4I6GjADFardoz4Lruw",
    //   "expires_in": 3600,
    //   "refresh_token": "1/tMBJ ... 27D-Hk6rpQYBA",
    //   "scope": "https://www.googleapis.com/auth/drive",
    //   "token_type": "Bearer"
    // }

    json = CkJsonObject_Create();
    tokenFilePath = "qa_data/tokens/googleDrive.json";
    CkJsonObject_LoadFile(json,tokenFilePath);

    oauth2 = CkOAuth2_Create();
    CkOAuth2_putAccessToken(oauth2,CkJsonObject_stringOf(json,"access_token"));
    CkOAuth2_putRefreshToken(oauth2,CkJsonObject_stringOf(json,"refresh_token"));

    CkOAuth2_putAuthorizationEndpoint(oauth2,"https://accounts.google.com/o/oauth2/v2/auth");
    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");
    CkOAuth2_putScope(oauth2,"https://www.googleapis.com/auth/drive");

    // Use OAuth2 to refresh the access token.
    success = CkOAuth2_RefreshAccessToken(oauth2);
    if (success != TRUE) {
        printf("%s\n",CkOAuth2_lastErrorText(oauth2));
        CkJsonObject_Dispose(json);
        CkOAuth2_Dispose(oauth2);
        return;
    }

    printf("%s\n",CkOAuth2_accessTokenResponse(oauth2));

    // Save the new access token to our JSON file (so we can refresh it again when needed).
    CkJsonObject_UpdateString(json,"access_token",CkOAuth2_accessToken(oauth2));

    fac = CkFileAccess_Create();
    CkFileAccess_WriteEntireTextFile(fac,tokenFilePath,CkJsonObject_emit(json),"utf-8",FALSE);

    printf("Access Token Refreshed!\n");


    CkJsonObject_Dispose(json);
    CkOAuth2_Dispose(oauth2);
    CkFileAccess_Dispose(fac);

    }