(C) HMRC OAuth2 Access Token

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Note: This example requires Chilkat v10.1.2 or greater.

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

void ChilkatSample(void)
    {
    HCkOAuth2 oauth2;
    const char *url;
    BOOL success;
    int numMsWaited;
    HCkJsonObject json;
    HCkDateTime dtExpire;
    HCkFileAccess fac;

    // To further clarify, see OAuth 2.0 Authorization Flow

    oauth2 = CkOAuth2_Create();

    // This should be the port in the localhost callback URL for your app.
    // Important: Make sure the callback URI in your HMRC developer app 
    // is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
    // The callback URL would look like "http://localhost:3017/" if the port number is 3017.

    // IMPORTANT: Don't forget to setup your HMRC application to use the Redirect URI "http://localhost:3017/" as shown
    // here: Configure Redirect URI for HMRC application
    CkOAuth2_putListenPort(oauth2,3017);

    CkOAuth2_putAuthorizationEndpoint(oauth2,"https://test-api.service.hmrc.gov.uk/oauth/authorize");
    CkOAuth2_putTokenEndpoint(oauth2,"https://test-api.service.hmrc.gov.uk/oauth/token");

    // Replace with your actual client ID
    CkOAuth2_putClientId(oauth2,"HMRC-CLIENT-ID");

    // The scopes are documented in the HMRC reference documentation for each API.
    // This example gets a read/write access token for the HMRC MTD VAT API.
    CkOAuth2_putScope(oauth2,"read:vat write:vat");

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    url = CkOAuth2_startAuth(oauth2);
    if (CkOAuth2_getLastMethodSuccess(oauth2) != TRUE) {
        printf("%s\n",CkOAuth2_lastErrorText(oauth2));
        CkOAuth2_Dispose(oauth2);
        return;
    }

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    success = CkOAuth2_LaunchBrowser(oauth2,url);
    if (success == FALSE) {
        printf("%s\n",CkOAuth2_lastErrorText(oauth2));
        CkOAuth2_Dispose(oauth2);
        return;
    }

    // Wait for the user to approve or deny authorization in the browser.
    numMsWaited = 0;
    while ((numMsWaited < 90000) && (CkOAuth2_getAuthFlowState(oauth2) < 3)) {
        CkOAuth2_SleepMs(oauth2,100);
        numMsWaited = numMsWaited + 100;
    }

    // If the browser does not respond within the specified time, AuthFlowState will be:
    // 
    // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
    // 2: Waiting for Final Response – The thread is awaiting the final access token response.
    // In either case, cancel the background task initiated by StartAuth.

    if (CkOAuth2_getAuthFlowState(oauth2) < 3) {
        CkOAuth2_Cancel(oauth2);
        printf("No response from the browser!\n");
        CkOAuth2_Dispose(oauth2);
        return;
    }

    // Check AuthFlowState to determine if authorization was granted, denied, or failed:
    // 
    // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
    // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
    // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

    if (CkOAuth2_getAuthFlowState(oauth2) == 5) {
        printf("OAuth2 failed to complete.\n");
        printf("%s\n",CkOAuth2_failureInfo(oauth2));
        CkOAuth2_Dispose(oauth2);
        return;
    }

    if (CkOAuth2_getAuthFlowState(oauth2) == 4) {
        printf("OAuth2 authorization was denied.\n");
        printf("%s\n",CkOAuth2_accessTokenResponse(oauth2));
        CkOAuth2_Dispose(oauth2);
        return;
    }

    if (CkOAuth2_getAuthFlowState(oauth2) != 3) {
        printf("Unexpected AuthFlowState:%d\n",CkOAuth2_getAuthFlowState(oauth2));
        CkOAuth2_Dispose(oauth2);
        return;
    }

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

    // Get the full JSON response:
    json = CkJsonObject_Create();
    CkJsonObject_Load(json,CkOAuth2_accessTokenResponse(oauth2));
    CkJsonObject_putEmitCompact(json,FALSE);
    printf("%s\n",CkJsonObject_emit(json));

    // The JSON response looks 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": "..."
    // }

    // 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 (CkJsonObject_HasMember(json,"expires_on") != TRUE) {
        dtExpire = CkDateTime_Create();
        CkDateTime_SetFromCurrentSystemTime(dtExpire);
        CkDateTime_AddSeconds(dtExpire,CkJsonObject_IntOf(json,"expires_in"));
        CkJsonObject_AppendString(json,"expires_on",CkDateTime_getAsUnixTimeStr(dtExpire,FALSE));
    }

    printf("%s\n",CkJsonObject_emit(json));

    // Save the JSON to a file for future requests.
    fac = CkFileAccess_Create();
    CkFileAccess_WriteEntireTextFile(fac,"qa_data/tokens/hmrc.json",CkJsonObject_emit(json),"utf-8",FALSE);


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

    }