(Unicode C++) Egyptian eReceipt OAuth2 Client Credentials

See more Egypt eReceipt Examples

Get an OAuth2 access token for the Egyptian eReceipt REST API using client credentials (no interactivity with a web browser required).

For more information, see https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/

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#include <CkHttpW.h>
#include <CkHttpRequestW.h>
#include <CkHttpResponseW.h>
#include <CkStringBuilderW.h>
#include <CkJsonObjectW.h>

void ChilkatSample(void)
    {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkHttpW http;
    bool success;

    // Note: Any provider of a REST API, such as the Egyptian government in this case, can make life 
    // much easier for developers by providing one or more of the following in the API documentation:
    // 
    // 1) A sample CURL statement for each API call.
    // 2) A Postman collection, or Swagger/OpenAPI specification file.
    // 3) A sample of a raw HTTP request and response for each API call.
    // 
    // The sample CURL statements or raw HTTP request/responses do not need to comprehensively show all 
    // possible options.  Providing a sample allows one to quickly make a successful API call.
    // It also allows for code generation directly from the CURL, Postman collection, or raw request/response,
    // and it tends to answer all questions about the format/structure of a request that, suprisingly,
    // remain ambiguous or not obvious in other forms of documentation.

    CkHttpRequestW req;
    req.AddParam(L"grant_type",L"client_credentials");
    // Use your actual client ID and client secret...
    req.AddParam(L"client_id",L"d0394a9f-0607-40de-a978-2d3eb8375b04");
    req.AddParam(L"client_secret",L"6d62315e-d65a-4e41-9112-4195ea834edf");

    req.AddHeader(L"posserial",L"1234567899");
    req.AddHeader(L"pososversion",L"os");
    req.AddHeader(L"posmodelframework",L"1");
    req.AddHeader(L"presharedkey",L"03ac674216f3e1...");

    // When writing this example, the documentation at https://sdk.invoicing.eta.gov.eg/ereceiptapi/01-authenticate-pos/
    // shows us the HTTP verb and path (POST /connect/token), however,
    // we don't see the actual domain where the request is to be sent.
    // What are the endpoints???
    // It took some searching, but we found some endpoints here:  https://sdk.invoicing.eta.gov.eg/faq/
    // It's not immediately apparent which endpoint is to be used with a given API call.
    // Why not just include the endpoint in the documentation for each REST API call?
    // Endpoints are literally the #1 thing that needs to be known.
    // They can't just be buried in a FAQ.  They should be up-front and obvious.
    // 
    // So.. we're guessing the endpoint is likely "https://invoicing.eta.gov.eg/connect/token"
    CkHttpResponseW *resp = http.PostUrlEncoded(L"https://invoicing.eta.gov.eg/connect/token",req);
    if (http.get_LastMethodSuccess() == false) {
        wprintf(L"%s\n",http.lastErrorText());
        return;
    }

    CkStringBuilderW sbResponseBody;
    resp->GetBodySb(sbResponseBody);

    CkJsonObjectW jResp;
    jResp.LoadSb(sbResponseBody);
    jResp.put_EmitCompact(false);

    wprintf(L"Response Body:\n");
    wprintf(L"%s\n",jResp.emit());

    int respStatusCode = resp->get_StatusCode();
    wprintf(L"Response Status Code = %d\n",respStatusCode);
    if (respStatusCode >= 400) {
        wprintf(L"Response Header:\n");
        wprintf(L"%s\n",resp->header());
        wprintf(L"Failed.\n");
        delete resp;
        return;
    }

    delete resp;

    // If successful, the OAuth2 access token JSON looks like this:

    // {
    //   "token_type": "Bearer",
    //   "access_token": "eyJraW......R2sbqrY",
    //   "expires_in": "3600",
    //   "scope": "..."
    // }

    const wchar_t *token_type = jResp.stringOf(L"token_type");
    const wchar_t *access_token = jResp.stringOf(L"access_token");
    const wchar_t *expires_in = jResp.stringOf(L"expires_in");
    const wchar_t *scope = jResp.stringOf(L"scope");
    }