(C) Twitter - Application Only Authentication

Demonstrates how to get a Twitter OAuth2 token for application-only authentication.

This allows you to issue authenticated requests on behalf of the application itself (as opposed to on behalf of a specific user). You don’t have the context of an authenticated user and this means that any request to API for endpoints that require user context, such as posting Tweets, will not work. However, the set of endpoints that will still be available can have a higher rate limit.

Your app will be able to, for example:

• Pull user timelines;
• Access friends and followers of any account;
• Access lists resources;
• Search in Tweets;
• Retrieve any user information;

And it will not be able to:

• Post Tweets or other resources;
• Connect to Streaming endpoints;
• Search for users;
• Use any geo endpoint;
• Access Direct Messages or account credentials;

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#include <C_CkHttp.h>
#include <C_CkHttpRequest.h>
#include <C_CkHttpResponse.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    const char *consumerKey;
    const char *consumerSecret;
    HCkHttp http;
    HCkHttpRequest req;
    HCkHttpResponse resp;
    HCkJsonObject json;

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

    // Note: Define your Twitter apps at https://apps.twitter.com/

    // We're going to send an HTTPS POST that looks like this:

    // POST /oauth2/token HTTP/1.1
    // Host: api.twitter.com
    // User-Agent: My Twitter App v1.0.23
    // Authorization: Basic eHZ6MWV2RlM0d0VFUFRHRUZQSEJvZzpMOHFxOVBaeVJn
    //                      NmllS0dFS2hab2xHQzB2SldMdzhpRUo4OERSZHlPZw==
    // Content-Type: application/x-www-form-urlencoded;charset=UTF-8
    // Content-Length: 29
    // Accept-Encoding: gzip
    // 
    // grant_type=client_credentials

    // Update these values with your consumer key and secret (also known as API key and API secret).
    consumerKey = "TWITTER_CONSUMER_KEY";
    consumerSecret = "TWITTER_CONSUMER_SECRET";

    http = CkHttp_Create();

    CkHttp_putBasicAuth(http,TRUE);
    CkHttp_putLogin(http,consumerKey);
    CkHttp_putPassword(http,consumerSecret);

    req = CkHttpRequest_Create();
    CkHttpRequest_AddParam(req,"grant_type","client_credentials");

    resp = CkHttp_PostUrlEncoded(http,"https://api.twitter.com/oauth2/token",req);
    if (CkHttp_getLastMethodSuccess(http) != TRUE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        return;
    }

    printf("Response Status Code: %d\n",CkHttpResponse_getStatusCode(resp));

    if (CkHttpResponse_getStatusCode(resp) != 200) {
        printf("Expected a 200 response status code for success.\n");
        printf("%s\n",CkHttpResponse_bodyStr(resp));
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        return;
    }

    // We should get a JSON response like this:

    // {
    //     "token_type":"bearer",
    //     "access_token":"..."
    // }

    json = CkJsonObject_Create();
    CkJsonObject_Load(json,CkHttpResponse_bodyStr(resp));

    printf("Access token = %s\n",CkJsonObject_stringOf(json,"access_token"));

    CkHttpResponse_Dispose(resp);


    CkHttp_Dispose(http);
    CkHttpRequest_Dispose(req);
    CkJsonObject_Dispose(json);

    }