#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <oqs/oqs.h>

/* Displays hexadecimal strings */
static void OQS_print_hex_string(const char *label, const uint8_t *str, size_t len) {
	printf("%-20s (%4zu bytes):  ", label, len);
	for (size_t i = 0; i < (len); i++) {
		printf("%02X", ((unsigned char *) (str))[i]);
	}
	printf("\n");
}

typedef struct magic_s {
	uint8_t val[32];
} magic_t;

static OQS_STATUS kem_test_correctness(const char *method_name) {

	OQS_KEM *kem = NULL;
	uint8_t *public_key = NULL;
	uint8_t *secret_key = NULL;
	uint8_t *ciphertext = NULL;
	uint8_t *shared_secret_e = NULL;
	uint8_t *shared_secret_d = NULL;
	OQS_STATUS rc, ret = OQS_ERROR;
	int rv;

	//The magic numbers are 32 random values.
	//The length of the magic number was chosen arbitrarilly to 32.
	magic_t magic = {{0xfa, 0xfa, 0xfa, 0xfa, 0xbc, 0xbc, 0xbc, 0xbc,
	                  0x15, 0x61, 0x15, 0x61, 0x15, 0x61, 0x15, 0x61,
	                  0xad, 0xad, 0x43, 0x43, 0xad, 0xad, 0x34, 0x34,
	                  0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78}};

	kem = OQS_KEM_new(method_name);
	if (kem == NULL) {
		return OQS_SUCCESS;
	}

	printf("================================================================================\n");
	printf("Sample computation for KEM %s\n", kem->method_name);
	printf("================================================================================\n");

	public_key = malloc(kem->length_public_key + sizeof(magic_t));
	secret_key = malloc(kem->length_secret_key + sizeof(magic_t));
	ciphertext = malloc(kem->length_ciphertext + sizeof(magic_t));
	shared_secret_e = malloc(kem->length_shared_secret + sizeof(magic_t));
	shared_secret_d = malloc(kem->length_shared_secret + sizeof(magic_t));

	//Set the magic numbers
	memcpy(public_key + kem->length_public_key, magic.val, sizeof(magic_t));
	memcpy(secret_key + kem->length_secret_key, magic.val, sizeof(magic_t));
	memcpy(ciphertext + kem->length_ciphertext, magic.val, sizeof(magic_t));
	memcpy(shared_secret_e + kem->length_shared_secret, magic.val, sizeof(magic_t));
	memcpy(shared_secret_d + kem->length_shared_secret, magic.val, sizeof(magic_t));

	if ((public_key == NULL) || (secret_key == NULL) || (ciphertext == NULL) || (shared_secret_e == NULL) || (shared_secret_d == NULL)) {
		fprintf(stderr, "ERROR: malloc failed\n");
		goto err;
	}

	rc = OQS_KEM_keypair(kem, public_key, secret_key);
	if (rc != OQS_SUCCESS) {
		fprintf(stderr, "ERROR: OQS_KEM_keypair failed\n");
		goto err;
	}

	rc = OQS_KEM_encaps(kem, ciphertext, shared_secret_e, public_key);
	if (rc != OQS_SUCCESS) {
		fprintf(stderr, "ERROR: OQS_KEM_encaps failed\n");
		goto err;
	}

	rc = OQS_KEM_decaps(kem, shared_secret_d, ciphertext, secret_key);
	if (rc != OQS_SUCCESS) {
		fprintf(stderr, "ERROR: OQS_KEM_decaps failed\n");
		goto err;
	}

	rv = memcmp(shared_secret_e, shared_secret_d, kem->length_shared_secret);
	if (rv != 0) {
		fprintf(stderr, "ERROR: shared secrets are not equal\n");
		OQS_print_hex_string("shared_secret_e", shared_secret_e, kem->length_shared_secret);
		OQS_print_hex_string("shared_secret_d", shared_secret_d, kem->length_shared_secret);
		goto err;
	} else {
		printf("shared secrets are equal\n");
	}

	rv = memcmp(public_key + kem->length_public_key, magic.val, sizeof(magic_t));
	rv |= memcmp(secret_key + kem->length_secret_key, magic.val, sizeof(magic_t));
	rv |= memcmp(ciphertext + kem->length_ciphertext, magic.val, sizeof(magic_t));
	rv |= memcmp(shared_secret_e + kem->length_shared_secret, magic.val, sizeof(magic_t));
	rv |= memcmp(shared_secret_d + kem->length_shared_secret, magic.val, sizeof(magic_t));
	if (rv != 0) {
		fprintf(stderr, "ERROR: Magic numbers do not match\n");
		goto err;
	}

	ret = OQS_SUCCESS;
	goto cleanup;

err:
	ret = OQS_ERROR;

cleanup:
	if (kem != NULL) {
		OQS_MEM_secure_free(secret_key, kem->length_secret_key);
		OQS_MEM_secure_free(shared_secret_e, kem->length_shared_secret);
		OQS_MEM_secure_free(shared_secret_d, kem->length_shared_secret);
	}
	OQS_MEM_insecure_free(public_key);
	OQS_MEM_insecure_free(ciphertext);
	OQS_KEM_free(kem);

	return ret;
}

int main() {

	int ret = EXIT_SUCCESS;
	OQS_STATUS rc;

	// Use system RNG in this program
	OQS_randombytes_switch_algorithm(OQS_RAND_alg_system);

	for (size_t i = 0; i < OQS_KEM_algs_length; i++) {
		rc = kem_test_correctness(OQS_KEM_alg_identifier(i));
		if (rc != OQS_SUCCESS) {
			ret = EXIT_FAILURE;
		}
	}

	return ret;
}