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

void ChilkatSample(void)
    {
    HCkHttp http;
    BOOL success;
    HCkHttpRequest req;
    HCkHttpResponse resp;
    HCkStringBuilder sbResponseBody;
    HCkJsonObject jResp;
    int respStatusCode;
    const char *token_type;
    const char *access_token;
    const char *expires_in;
    const char *scope;

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

    http = CkHttp_Create();

    // 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.

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

    CkHttpRequest_AddHeader(req,"posserial","1234567899");
    CkHttpRequest_AddHeader(req,"pososversion","os");
    CkHttpRequest_AddHeader(req,"posmodelframework","1");
    CkHttpRequest_AddHeader(req,"presharedkey","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"
    resp = CkHttp_PostUrlEncoded(http,"https://invoicing.eta.gov.eg/connect/token",req);
    if (CkHttp_getLastMethodSuccess(http) == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        return;
    }

    sbResponseBody = CkStringBuilder_Create();
    CkHttpResponse_GetBodySb(resp,sbResponseBody);

    jResp = CkJsonObject_Create();
    CkJsonObject_LoadSb(jResp,sbResponseBody);
    CkJsonObject_putEmitCompact(jResp,FALSE);

    printf("Response Body:\n");
    printf("%s\n",CkJsonObject_emit(jResp));

    respStatusCode = CkHttpResponse_getStatusCode(resp);
    printf("Response Status Code = %d\n",respStatusCode);
    if (respStatusCode >= 400) {
        printf("Response Header:\n");
        printf("%s\n",CkHttpResponse_header(resp));
        printf("Failed.\n");
        CkHttpResponse_Dispose(resp);
        CkHttp_Dispose(http);
        CkHttpRequest_Dispose(req);
        CkStringBuilder_Dispose(sbResponseBody);
        CkJsonObject_Dispose(jResp);
        return;
    }

    CkHttpResponse_Dispose(resp);

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

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

    token_type = CkJsonObject_stringOf(jResp,"token_type");
    access_token = CkJsonObject_stringOf(jResp,"access_token");
    expires_in = CkJsonObject_stringOf(jResp,"expires_in");
    scope = CkJsonObject_stringOf(jResp,"scope");


    CkHttp_Dispose(http);
    CkHttpRequest_Dispose(req);
    CkStringBuilder_Dispose(sbResponseBody);
    CkJsonObject_Dispose(jResp);

    }