(Unicode C) Refresh HMRC OAuth2 Access Token

Demonstrates how to refresh an HMRC access token.

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#include <C_CkJsonObjectW.h>
#include <C_CkOAuth2W.h>
#include <C_CkDateTimeW.h>
#include <C_CkStringBuilderW.h>

void ChilkatSample(void)
    {
    HCkJsonObjectW jsonToken;
    BOOL success;
    HCkOAuth2W oauth2;
    HCkDateTimeW dtExpire;
    HCkStringBuilderW sbJson;

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

    // See Get HMRC Access Token 
    // for sample code showing how to obtain a HMRC access token for desktop apps.

    // It is assumed we previously obtained an OAuth2 access token for HMRC.

    jsonToken = CkJsonObjectW_Create();
    success = CkJsonObjectW_LoadFile(jsonToken,L"qa_data/tokens/hmrc.json");
    if (success != TRUE) {
        wprintf(L"Failed to load hmrc.json\n");
        CkJsonObjectW_Dispose(jsonToken);
        return;
    }

    // The access token JSON looks something like this:

    // {
    //   "token_type": "Bearer",
    //   "scope": "user_impersonation",
    //   "expires_in": "3599",
    //   "ext_expires_in": "0",
    //   "expires_on": "1524783438",
    //   "not_before": "1524779538",
    //   "resource": "https://mydomain.api.crm.dynamics.com",
    //   "access_token": "...",
    //   "refresh_token": "...",
    //   "id_token": "..."
    // }

    oauth2 = CkOAuth2W_Create();

    CkOAuth2W_putTokenEndpoint(oauth2,L"https://test-api.service.hmrc.gov.uk/oauth/token");

    // Replace these with actual values.
    CkOAuth2W_putClientId(oauth2,L"HMRC-CLIENT-ID");
    CkOAuth2W_putClientSecret(oauth2,L"HMRC-CLIENT-SECRET");

    // Get the "refresh_token"
    CkOAuth2W_putRefreshToken(oauth2,CkJsonObjectW_stringOf(jsonToken,L"refresh_token"));

    // Send the HTTP POST to refresh the access token..
    success = CkOAuth2W_RefreshAccessToken(oauth2);
    if (success != TRUE) {
        wprintf(L"%s\n",CkOAuth2W_lastErrorText(oauth2));
        CkJsonObjectW_Dispose(jsonToken);
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    // Load the access token response into the json object 
    CkJsonObjectW_Load(jsonToken,CkOAuth2W_accessTokenResponse(oauth2));

    // 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 (CkJsonObjectW_HasMember(jsonToken,L"expires_on") == FALSE) {
        dtExpire = CkDateTimeW_Create();
        CkDateTimeW_SetFromCurrentSystemTime(dtExpire);
        CkDateTimeW_AddSeconds(dtExpire,CkJsonObjectW_IntOf(jsonToken,L"expires_in"));
        CkJsonObjectW_AppendString(jsonToken,L"expires_on",CkDateTimeW_getAsUnixTimeStr(dtExpire,FALSE));
    }

    // Save the new JSON access token response to a file.
    // The access + refresh tokens contained in this JSON will be needed for the next refresh.
    sbJson = CkStringBuilderW_Create();
    CkJsonObjectW_putEmitCompact(jsonToken,FALSE);
    CkJsonObjectW_EmitSb(jsonToken,sbJson);
    CkStringBuilderW_WriteFile(sbJson,L"qa_data/tokens/hmrc.json",L"utf-8",FALSE);

    wprintf(L"OAuth2 authorization granted!\n");
    wprintf(L"New Access Token = %s\n",CkOAuth2W_accessToken(oauth2));


    CkJsonObjectW_Dispose(jsonToken);
    CkOAuth2W_Dispose(oauth2);
    CkDateTimeW_Dispose(dtExpire);
    CkStringBuilderW_Dispose(sbJson);

    }