(Unicode C++) X.com OAuth 2.0 Authorization Code with PKCE

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

For more information, see https://docs.x.com/resources/fundamentals/authentication/oauth-2-0/authorization-code

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#include <CkOAuth2W.h>
#include <CkJsonObjectW.h>
#include <CkDateTimeW.h>

void ChilkatSample(void)
    {
    // For more information about the OAuth2, see OAuth 2.0 Authorization Flow

    CkOAuth2W oauth2;

    // The port should match the Authorized Redirect URL in your X.com app, 
    // which would look like "http://127.0.0.1:3017/"
    // See the screenshot below of the App Settings in the X Developer Portal
    oauth2.put_LocalHost(L"127.0.0.1");
    oauth2.put_ListenPort(3017);

    oauth2.put_AuthorizationEndpoint(L"https://x.com/i/oauth2/authorize");
    oauth2.put_TokenEndpoint(L"https://api.x.com/2/oauth2/token");

    // Replace this with your actual X.com OAuth2 Client ID and Client Secret
    oauth2.put_ClientId(L"OAUTH2_CLIENT_ID");
    oauth2.put_ClientSecret(L"OAUTH2_CLIENT_SECRET");

    // This is for Require Proof Key for Code Exchange (PKCE)
    // See OAuth2 PKCE Explained
    oauth2.put_CodeChallenge(true);
    oauth2.put_CodeChallengeMethod(L"S256");

    // Space separated scopes...
    oauth2.put_Scope(L"tweet.read tweet.write users.read follows.read follows.write offline.access like.read like.write block.read block.write");

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    const wchar_t *url = oauth2.startAuth();
    if (oauth2.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",oauth2.lastErrorText());
        return;
    }

    wprintf(L"url = %s\n",url);

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    bool success = oauth2.LaunchBrowser(url);
    if (success == false) {
        wprintf(L"%s\n",oauth2.lastErrorText());
        return;
    }

    // Wait for the user to approve or deny authorization in the browser.
    int numMsWaited = 0;
    while ((numMsWaited < 10000) && (oauth2.get_AuthFlowState() < 3)) {
        oauth2.SleepMs(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 (oauth2.get_AuthFlowState() < 3) {
        oauth2.Cancel();
        wprintf(L"No response from the browser!\n");
        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 (oauth2.get_AuthFlowState() == 5) {
        wprintf(L"OAuth2 failed to complete.\n");
        wprintf(L"%s\n",oauth2.failureInfo());
        return;
    }

    if (oauth2.get_AuthFlowState() == 4) {
        wprintf(L"OAuth2 authorization was denied.\n");
        wprintf(L"%s\n",oauth2.accessTokenResponse());
        return;
    }

    if (oauth2.get_AuthFlowState() != 3) {
        wprintf(L"Unexpected AuthFlowState:%d\n",oauth2.get_AuthFlowState());
        return;
    }

    wprintf(L"OAuth2 authorization granted!\n");

    CkJsonObjectW json;
    json.Load(oauth2.accessTokenResponse());
    json.put_EmitCompact(false);

    // 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 (json.HasMember(L"expires_on") == false) {
        CkDateTimeW dtExpire;
        dtExpire.SetFromCurrentSystemTime();
        dtExpire.AddSeconds(json.IntOf(L"expires_in"));
        json.AppendString(L"expires_on",dtExpire.getAsUnixTimeStr(false));
    }

    wprintf(L"Access Token Response = %s\n",json.emit());

    // A sample access token response:

    // {
    //   "token_type": "bearer",
    //   "expires_in": 7200,
    //   "access_token": "VmNDLVZiYUZwejY5Mkx3RblFTmo3ek1leTRGclMuZFVOUTVUTWpNbVZKb1N5OjE3NDAxNjk4MDVxNTE6MToxOaF0OjE",
    //   "scope": "block.read follows.read offline.access tweet.write block.write like.write like.read users.read tweet.read follows.write",
    //   "refresh_token": "eThOWVVFSTRqdVp3QTFndGsxM2ZGZmFyNWVrU0phM1JKbGdrbGNWRGJzb1loOjE3NDAwMjk4MDUxNTI6MTowOnJ0OjE"
    // }

    wprintf(L"Access Token = %s\n",oauth2.accessToken());

    // Save the JSON access token response to a file for subsequent use..
    json.WriteFile(L"qa_data/tokens/x.json");

    // 
    }