#include <errno.h>
#include <sgx_urts.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/core_names.h>
#include <openssl/sha.h>
#include <openssl/ec.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/evp.h>

#include <sgx_tcrypto.h>

#include "enclave_u.h"
#include "proxy.h"
#include "util.h"

struct ProxysetupArgs {
    char* sealed_key_file_path;
    char* sgx_token_path;
};

char* proxysetup_syntax(void) {
    return
        "proxysetup      implementation of the enclave-powered SignatureProxy\n"
        "                outputs public key on stdout\n"
        "    -s <path>   file path of the sealed proxy key\n"
        "    -t <path>   file path of the sgx token\n";
}



static EVP_PKEY *sgx_public_to_EVP_PKEY(const sgx_ec256_public_t *p_public)
{
	EVP_PKEY *evp_key = NULL;
	EVP_PKEY_CTX *pkey_ctx = NULL;
	BIGNUM *bn_pub_x = NULL;
	BIGNUM *bn_pub_y = NULL;
	EC_POINT *point = NULL;
    EC_GROUP* group = NULL;
	OSSL_PARAM_BLD *params_build = NULL;
	OSSL_PARAM *params = NULL;
	const char *curvename = NULL;
	int nid = 0;
	size_t key_len;
	unsigned char pub_key[SGX_ECP256_KEY_SIZE+4];

    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
	if (group == NULL)
        return NULL;

	do {
		// converts the x value of public key, represented as positive integer in little-endian into a BIGNUM
		bn_pub_x = BN_lebin2bn((unsigned char*)p_public->gx, sizeof(p_public->gx), bn_pub_x);
		if (NULL == bn_pub_x) {
			break;
		}
		// converts the y value of public key, represented as positive integer in little-endian into a BIGNUM
		bn_pub_y = BN_lebin2bn((unsigned char*)p_public->gy, sizeof(p_public->gy), bn_pub_y);
		if (NULL == bn_pub_y) {
			break;
		}
		// creates new point and assigned the group object that the point relates to
		point = EC_POINT_new(group);
		if (NULL == point) {
			break;
		}

		// sets point based on public key's x,y coordinates
		if (1 != EC_POINT_set_affine_coordinates(group, point, bn_pub_x, bn_pub_y, NULL)) {
			break;
		}

		// check point if the point is on curve
		if (1 != EC_POINT_is_on_curve(group, point, NULL)) {
			break;
		}

		// convert point to octet string
		key_len = EC_POINT_point2oct(group, point, POINT_CONVERSION_COMPRESSED, pub_key, sizeof(pub_key), NULL);
		if (key_len == 0) {
			break;
		}

		// build OSSL_PARAM
		params_build = OSSL_PARAM_BLD_new();
		if (NULL == params_build) {
			break;
		}
		nid = EC_GROUP_get_curve_name(group);
		if (nid == NID_undef) {
			break;
		}
		curvename = OBJ_nid2sn(nid);
		if (curvename == NULL) {
			break;
		}
		if (1 != OSSL_PARAM_BLD_push_utf8_string(params_build, "group", curvename, 0)) {
			break;
		}
		if (1 != OSSL_PARAM_BLD_push_octet_string(params_build, OSSL_PKEY_PARAM_PUB_KEY, pub_key, key_len)) {
			break;
		}
		params = OSSL_PARAM_BLD_to_param(params_build);
		if (NULL == params) {
			break;
		}

		// get pkey from params
		pkey_ctx = EVP_PKEY_CTX_new_from_name(NULL, "EC", NULL);
		if (NULL == pkey_ctx) {
			break;
		}
		if (1 != EVP_PKEY_fromdata_init(pkey_ctx)) {
			break;
		}
		if (1 != EVP_PKEY_fromdata(pkey_ctx, &evp_key, EVP_PKEY_PUBLIC_KEY, params)) {
			EVP_PKEY_free(evp_key);
			evp_key = NULL;
		}
	} while(0);

	BN_clear_free(bn_pub_x);
	BN_clear_free(bn_pub_y);
	EC_POINT_clear_free(point);
	OSSL_PARAM_free(params);
	OSSL_PARAM_BLD_free(params_build);
	EVP_PKEY_CTX_free(pkey_ctx);
    EC_GROUP_free(group);

	return evp_key;
}

static int EVP_PKEY_to_sgx_public(EVP_PKEY* ecdsa_key, sgx_ec256_public_t* sgx_public) {
    EC_GROUP* group = NULL;
	EC_POINT *point = NULL;
    BIGNUM* pub_x = NULL;
	BIGNUM* pub_y = NULL;
    size_t ec_key_buf_len = 0;
    unsigned char ec_key_buf[1024];
    int ret;
    int retval;

    group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
	if (group == NULL)
        return 1;

    point = EC_POINT_new(group);
    if (point == NULL)
        return 2;

    ret = EVP_PKEY_get_octet_string_param(ecdsa_key, OSSL_PKEY_PARAM_PUB_KEY, ec_key_buf, 1024, &ec_key_buf_len);
    if (ret != 1)
        return 3;

    ret = EC_POINT_oct2point(group, point, ec_key_buf, ec_key_buf_len, NULL);
    if (ret != 1){
        retval = 4;
        goto cleanup;
    }

    pub_x = BN_new();
    pub_y = BN_new();

    ret = EC_POINT_get_affine_coordinates(group, point, pub_x, pub_y, NULL);
    if (ret != 1){
        retval = 5;
        goto cleanup;
    }

    ret = BN_bn2lebinpad(pub_x, sgx_public->gx, SGX_ECP256_KEY_SIZE);
    if (ret == -1){
        retval = 6;
        goto cleanup;
    }

    ret = BN_bn2lebinpad(pub_y, sgx_public->gy, SGX_ECP256_KEY_SIZE);
    if (ret == -1){
        retval = 7;
        goto cleanup;
    }

cleanup:
    if (pub_x != NULL)
        BN_clear_free(pub_x);
    if (pub_y != NULL)
        BN_clear_free(pub_y);
    if (point != NULL)
        EC_POINT_clear_free(point);
    if (group != NULL)
        EC_GROUP_free(group);

    return (retval);
}

/*
sgx_status_t pfz_ecdsa_verify_hash(const uint8_t *p_data,
                              const sgx_ec256_public_t *p_public,
                              const sgx_ec256_signature_t *p_signature,
                              uint8_t *p_result,
                              sgx_ecc_state_handle_t ecc_handle)
{
	if ((ecc_handle == NULL) || (p_public == NULL) || (p_signature == NULL) ||
		(p_data == NULL) || (p_result == NULL)) {
		return SGX_ERROR_INVALID_PARAMETER;
	}

	EVP_PKEY_CTX *ctx = NULL;
	EVP_PKEY *public_key = NULL;
	BIGNUM *bn_r = NULL;
	BIGNUM *bn_s = NULL;
	ECDSA_SIG *ecdsa_sig = NULL;
	unsigned char *sig_data = NULL;
	size_t sig_size = 0;
	sgx_status_t retval = SGX_ERROR_UNEXPECTED;
	int ret = -1;

	*p_result = SGX_EC_INVALID_SIGNATURE;

	do {
		public_key = pfz_get_pub_key_from_coords(p_public, ecc_handle);
		if(NULL == public_key) {
			break;
		}
		// converts the x value of the signature, represented as positive integer in little-endian into a BIGNUM
		//
		bn_r = BN_lebin2bn((unsigned char*)p_signature->x, sizeof(p_signature->x), 0);
		if (NULL == bn_r) {
			break;
		}

		// converts the y value of the signature, represented as positive integer in little-endian into a BIGNUM
		//
		bn_s = BN_lebin2bn((unsigned char*)p_signature->y, sizeof(p_signature->y), 0);
		if (NULL == bn_s) {
			break;
		}


		// allocates a new ECDSA_SIG structure (note: this function also allocates the BIGNUMs) and initialize it
		//
		ecdsa_sig = ECDSA_SIG_new();
		if (NULL == ecdsa_sig) {
			retval = SGX_ERROR_OUT_OF_MEMORY;
			break;
		}

		// setes the r and s values of ecdsa_sig
		// calling this function transfers the memory management of the values to the ECDSA_SIG object,
		// and therefore the values that have been passed in should not be freed directly after this function has been called
		//
		if (1 != ECDSA_SIG_set0(ecdsa_sig, bn_r, bn_s)) {
			ECDSA_SIG_free(ecdsa_sig);
			ecdsa_sig = NULL;
			break;
		}
		sig_size = i2d_ECDSA_SIG(ecdsa_sig, &sig_data);
		if (sig_size <= 0) {
			break;
		}
		ctx = EVP_PKEY_CTX_new(public_key, NULL);
		if (!ctx) {
			break;
		}
		if (1 != EVP_PKEY_verify_init(ctx)) {
			break;
		}
		if (1 != EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256())) {
			break;
		}
		ret = EVP_PKEY_verify(ctx, sig_data, sig_size, p_data, SGX_SHA256_HASH_SIZE);
		if (ret < 0) {
			break;
		}

		// sets the p_result based on verification result
		//
		if (ret == 1)
			*p_result = SGX_EC_VALID;

		retval = SGX_SUCCESS;
	} while(0);

	if (ecdsa_sig) { 
		ECDSA_SIG_free(ecdsa_sig);
		bn_r = NULL;
		bn_s = NULL;
	}
	if (ctx)
		EVP_PKEY_CTX_free(ctx);
	if (public_key)
		EVP_PKEY_free(public_key);
	if (bn_r)
		BN_clear_free(bn_r);
	if (bn_s)
		BN_clear_free(bn_s);

	return retval;
}


sgx_status_t pfz_ecc256_open_context(sgx_ecc_state_handle_t* p_ecc_handle)
{
	if (p_ecc_handle == NULL) {
		return SGX_ERROR_INVALID_PARAMETER;
	}

	sgx_status_t retval = SGX_SUCCESS;

	EC_GROUP* ec_group = EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1);
	if (NULL == ec_group) {
		retval = SGX_ERROR_UNEXPECTED;
	} else {
		*p_ecc_handle = (void*)ec_group;
	}
	return retval;
}

sgx_status_t pfz_ecdsa_verify(const uint8_t *p_data,
    uint32_t data_size,
    const sgx_ec256_public_t *p_public,
    const sgx_ec256_signature_t *p_signature,
    uint8_t *p_result,
    sgx_ecc_state_handle_t ecc_handle)
{
	if ((ecc_handle == NULL) || (p_public == NULL) || (p_signature == NULL) ||
		(p_data == NULL) || (data_size < 1) || (p_result == NULL)) {
		return SGX_ERROR_INVALID_PARAMETER;
	}
	unsigned char digest[SGX_SHA256_HASH_SIZE] = { 0 };

	SHA256((const unsigned char *)p_data, data_size, (unsigned char *)digest);
	return (pfz_ecdsa_verify_hash(digest, p_public, p_signature, p_result, ecc_handle));
}
*/

int handle_proxysetup(int argc, char** argv) {
    struct ProxysetupArgs args = {
        NULL,
        NULL
    };

    FILE* sealed_file;

    sgx_status_t sgx_ret;

    /*
     * Parse Input
     */

    int i = 0;
    while(i < argc) {
        if(strcmp(argv[i], "-s")==0 && argc-i >=2){
            args.sealed_key_file_path = argv[i+1];
            i += 2;
        }else if(strcmp(argv[i], "-t")==0 && argc-i >=2){
            args.sgx_token_path = argv[i+1];
            i += 2;
        }else
            syntax_exit();
    }

    if(args.sealed_key_file_path == NULL)
        syntax_exit();

    /*
     * Initialize SGX Enclave
     */

    if (initialize_enclave(args.sgx_token_path) != 0)
        exit(1);

    /*
     * Setup Sealed Keypair
     */

    sealed_file = fopen(args.sealed_key_file_path, "wb");
    if(sealed_file == NULL){
        perror("Error opening sealed_key_file file");
        exit(1);
    }

    int sealed_size;
    sgx_ret = get_sealed_size(get_global_eid(), &sealed_size);
    if (sgx_ret != SGX_SUCCESS) {
        print_error_message(sgx_ret);
        exit (1);
    }
    uint8_t* sealed = malloc(sizeof(uint8_t)*sealed_size);
    if (sealed == NULL) {
        fprintf(stderr, "failed to allocate for sealed key");
        exit(1);
    }

    /*
     * Use Enclave To Generate Keypair
     */

    generate_key_pair(get_global_eid(), &sgx_ret, sealed, sealed_size);
    if (sgx_ret != SGX_SUCCESS) {
        print_error_message(sgx_ret);
        exit (1);
    }

    /*
     * Store Sealed Keypair
     */

    if (fwrite(sealed, sealed_size, 1, sealed_file) != 1 || ferror(sealed_file) != 0) {
        fprintf(stderr, "failed to write sealed key");
        exit(1);
    }
    fflush(sealed_file);
    fclose(sealed_file);

    /*
     * Fetch Public Key From Enclave And Print
     */

    sgx_ec256_public_t sgx_public_key;
    get_public_key(get_global_eid(), &sgx_ret, sealed, sealed_size, (uint8_t*)&sgx_public_key);
    if (sgx_ret != SGX_SUCCESS) {
        print_error_message(sgx_ret);
        exit (1);
    }

    EVP_PKEY* public_key = sgx_public_to_EVP_PKEY(&sgx_public_key);

    if (PEM_write_PUBKEY(stdout, public_key, NULL, NULL) != 1) {
        fprintf(stderr, "could not write publickey\n");
        exit (EXIT_FAILURE);
    }

    fflush(stdout);

    EVP_PKEY_free(public_key);
    free(sealed);

    exit(0);
}