#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <openssl/ec.h>
#include <openssl/objects.h>
#include <openssl/evp.h>

int
list_curves()
{
    size_t            len = EC_get_builtin_curves(NULL, 0);
    EC_builtin_curve *curves = OPENSSL_malloc(sizeof(EC_builtin_curve) * len);
    if (!curves) {
        fprintf(stderr, "Allocation failed.\n");
        return 1;
    }
    if (!EC_get_builtin_curves(curves, len)) {
        OPENSSL_free(curves);
        fprintf(stderr, "Failed to get curves.\n");
        return 1;
    }
    for (size_t i = 0; i < len; i++) {
        const char *sname = OBJ_nid2sn(curves[i].nid);
        if (!sname) {
            continue;
        }
        printf("%s\n", sname);
    }
    OPENSSL_free(curves);
    return 0;
}

static void
print_hash(const EVP_MD *md, const char *from, const char *to, void *arg)
{
    if (!md) {
        return;
    }
    if (strstr(from, "rsa") || strstr(from, "RSA")) {
        return;
    }
    printf("%s\n", from);
}

int
list_hashes()
{
    EVP_MD_do_all_sorted(print_hash, NULL);
    return 0;
}

static void
print_cipher(const EVP_CIPHER *cipher, const char *from, const char *to, void *x)
{
    if (!cipher) {
        return;
    }
    printf("%s\n", from);
}

int
list_ciphers()
{
    EVP_CIPHER_do_all_sorted(print_cipher, NULL);
    return 0;
}

int
list_publickey()
{
    for (size_t i = 0; i < EVP_PKEY_meth_get_count(); i++) {
        const EVP_PKEY_METHOD *pmeth = EVP_PKEY_meth_get0(i);
        int                    id = 0;
        EVP_PKEY_meth_get0_info(&id, NULL, pmeth);
        printf("%s\n", OBJ_nid2ln(id));
    }
    return 0;
}

int
main(int argc, char *argv[])
{
    if (argc != 2) {
        fprintf(stderr, "Usage: opensslfeatures [curves|hashes|ciphers|publickey]\n");
        return 1;
    }
    if (!strcmp(argv[1], "hashes")) {
        return list_hashes();
    }
    if (!strcmp(argv[1], "ciphers")) {
        return list_ciphers();
    }
    if (!strcmp(argv[1], "curves")) {
        return list_curves();
    }
    if (!strcmp(argv[1], "publickey")) {
        return list_publickey();
    }
    fprintf(stderr, "Unknown command: %s\n", argv[1]);
    return 1;
}