/*
 * Quick demo of how to use libjwt using a HS256.
 *
 * @author gback, CS 3214, Spring 2018, updated Spring 2021
 */
#include <jwt.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <errno.h>

static const char * NEVER_EMBED_A_SECRET_IN_CODE = "supa secret";

static void 
die(const char *msg, int error)
{
    fprintf(stderr, "%s: %s\n", msg, strerror(error));
    exit(EXIT_FAILURE);
}

int
main()
{
    jwt_t *mytoken;

    int rc = jwt_new(&mytoken);
    if (rc)
        die("jwt_new", rc);

    rc = jwt_add_grant(mytoken, "sub", "user0");
    if (rc)
        die("jwt_add_grant sub", rc);

    time_t now = time(NULL);
    rc = jwt_add_grant_int(mytoken, "iat", now);
    if (rc)
        die("jwt_add_grant iat", rc);

    rc = jwt_add_grant_int(mytoken, "exp", now + 3600 * 24);
    if (rc)
        die("jwt_add_grant exp", rc);

    rc = jwt_set_alg(mytoken, JWT_ALG_HS256, 
            (unsigned char *)NEVER_EMBED_A_SECRET_IN_CODE, 
            strlen(NEVER_EMBED_A_SECRET_IN_CODE));
    if (rc)
        die("jwt_set_alg", rc);

    printf("dump:\n");
    rc = jwt_dump_fp(mytoken, stdout, 1);
    if (rc)
        die("jwt_dump_fp", rc);

    char *encoded = jwt_encode_str(mytoken);
    if (encoded == NULL)
        die("jwt_encode_str", ENOMEM);

    printf("encoded as %s\nTry entering this at jwt.io\n", encoded);

    jwt_t *ymtoken;
    rc = jwt_decode(&ymtoken, encoded, 
            (unsigned char *)NEVER_EMBED_A_SECRET_IN_CODE, 
            strlen(NEVER_EMBED_A_SECRET_IN_CODE));
    if (rc)
        die("jwt_decode", rc);

    char *grants = jwt_get_grants_json(ymtoken, NULL); // NULL means all
    if (grants == NULL)
        die("jwt_get_grants_json", ENOMEM);

    printf("redecoded: %s\n", grants);
}