/**
 * famtool - a tool for creating and verifying router families
 */
#include <cassert>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include "Crypto.h"
#include "RouterInfo.h"
#include "Base.h"
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/evp.h>
#include <openssl/ec.h>
#include <openssl/ssl.h>

using namespace i2p::crypto;
using namespace i2p::data;

static void usage(const std::string & name)
{
	std::cout << "usage: " << name << " [-h] [-v] [-g -n family -c family.crt -k family.pem] [-s -n family -k family.pem -i router.keys -f router.info] [-V -c family.crt -f router.info]" << std::endl;
}

static void printhelp(const std::string & name)
{
	usage(name);
	std::cout << std::endl;
	std::cout << "generate a new family signing key for family called ``i2pfam''" << std::endl;
	std::cout << name << " -g -n i2pfam -c myfam.crt -k myfam.pem" << std::endl << std::endl;
	std::cout << "sign a router info with family signing key" << std::endl;
	std::cout << name << " -s -n i2pfam -k myfam.pem -i router.keys -f router.info" << std::endl << std::endl;
	std::cout << "verify signed router.info" << std::endl;
	std::cout << name << " -V -n i2pfam -c myfam.pem -f router.info" << std::endl << std::endl;
}

static std::shared_ptr<Verifier> LoadCertificate (const std::string& filename)
{
	std::shared_ptr<Verifier> verifier;
	SSL_CTX * ctx = SSL_CTX_new (TLSv1_method ());
	int ret = SSL_CTX_use_certificate_file (ctx, filename.c_str (), SSL_FILETYPE_PEM); 
	if (ret)
	{
		SSL * ssl = SSL_new (ctx);
		X509 * cert = SSL_get_certificate (ssl);
		if (cert)
		{
			// extract issuer name
			char name[100];
			X509_NAME_oneline (X509_get_issuer_name(cert), name, 100);
			char * cn = strstr (name, "CN=");
			if (cn)
			{
				cn += 3;
				char * family = strstr (cn, ".family");
				if (family) family[0] = 0;
			}
			auto pkey = X509_get_pubkey (cert);

			EC_KEY * ecKey = EVP_PKEY_get1_EC_KEY (pkey);
			if (ecKey)
			{
				auto group = EC_KEY_get0_group (ecKey);
				if (group)
				{
					int curve = EC_GROUP_get_curve_name (group);
					if (curve == NID_X9_62_prime256v1)
					{
						uint8_t signingKey[64];
						BIGNUM * x = BN_new(), * y = BN_new();
						EC_POINT_get_affine_coordinates_GFp (group,
						EC_KEY_get0_public_key (ecKey), x, y, NULL);
						bn2buf (x, signingKey, 32);
						bn2buf (y, signingKey + 32, 32);
						BN_free (x); BN_free (y);
						verifier = std::make_shared<i2p::crypto::ECDSAP256Verifier>();
			verifier->SetPublicKey (signingKey);
					}
				}
				EC_KEY_free (ecKey);
			}
			EVP_PKEY_free (pkey);
		}
		SSL_free (ssl);
	}
	SSL_CTX_free (ctx);
	return verifier;
}

static bool CreateFamilySignature (const std::string& family, const IdentHash& ident, const std::string & filename, std::string & sig)
{
	SSL_CTX * ctx = SSL_CTX_new (TLSv1_method ());
	int ret = SSL_CTX_use_PrivateKey_file (ctx, filename.c_str (), SSL_FILETYPE_PEM); 
	if (ret)
	{
		SSL * ssl = SSL_new (ctx);
		EVP_PKEY * pkey = SSL_get_privatekey (ssl);
		EC_KEY * ecKey = EVP_PKEY_get1_EC_KEY (pkey);
		if (ecKey)
		{
			auto group = EC_KEY_get0_group (ecKey);
			if (group)
			{
				int curve = EC_GROUP_get_curve_name (group);
				if (curve == NID_X9_62_prime256v1)
				{
					uint8_t signingPrivateKey[32], buf[50], signature[64];
					bn2buf (EC_KEY_get0_private_key (ecKey), signingPrivateKey, 32);
					ECDSAP256Signer signer (signingPrivateKey);
					size_t len = family.length ();
					memcpy (buf, family.c_str (), len);
					memcpy (buf + len, (const uint8_t *)ident, 32);
					len += 32;
					signer.Sign (buf, len, signature);
					len = Base64EncodingBufferSize (64);
					char * b64 = new char[len+1];
					len = ByteStreamToBase64 (signature, 64, b64, len);
					b64[len] = 0;
					sig = b64;
					delete[] b64;
				}
				else
					return false;
			}
		}
		SSL_free (ssl);
	}
	else
		return false;
	SSL_CTX_free (ctx);
	return true;
}

int main(int argc, char * argv[])
{
	if (argc == 1) {
		usage(argv[0]);
		return -1;
	}
	int opt;
	bool verbose = false;
	bool help = false;
	bool gen = false;
	bool sign = false;
	bool verify = false;
	std::string fam;
	std::string privkey;
	std::string certfile;
	std::string infile;
	std::string infofile;
	std::string outfile;
	while((opt = getopt(argc, argv, "vVhgsn:i:c:k:o:f:")) != -1) {
		switch(opt) {
		case 'v':
			verbose = true;
			break;
		case 'h':
			help = true;
			break;
		case 'g':
			gen = true;
			break;
		case 'n':
			fam = std::string(argv[optind-1]);
			if (fam.size() + 32 > 50) {
				std::cout << "family name too long" << std::endl;
				return 1;
			}
			break;
		case 'f':
			infofile = std::string(argv[optind-1]);
			break;
		case 'i':
			infile = std::string(argv[optind-1]);
			break;
		case 'o':
			outfile = std::string(argv[optind-1]);
		case 'c':
			certfile = std::string(argv[optind-1]);
			break;
		case 'k':
			privkey = std::string(argv[optind-1]);
			break;
		case 'V':
			verify = true;
			break;
		case 's':
			sign = true;
			break;
		default:
			usage(argv[0]);
			return -1;
		}
	}
	if(help) {
		printhelp(argv[0]);
		return 0;
	}

	InitCrypto(false, true, true, false);

	if(!fam.size()) {
		// no family name
		std::cout << "no family name specified" << std::endl;
		return 1;
	}
	// generate family key code
	if(gen) {
		if(!privkey.size()) privkey = fam + ".key";
		if(!certfile.size()) certfile = fam + ".crt";

		std::string cn = fam + ".family.i2p.net";


		FILE * privf = fopen(privkey.c_str(), "w");
		if(!privf) {
			fprintf(stderr, "cannot open %s: %s\n", privkey.c_str(), strerror(errno));
			return 1;
		}

		FILE * certf = fopen(certfile.c_str(), "w");
		if(!certf) {
			fprintf(stderr, "cannot open %s: %s\n", certfile.c_str(), strerror(errno));
			return 1;
		}

		// openssl fagmastery starts here

		EC_KEY * k_priv = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
		assert(k_priv);
		EC_KEY_set_asn1_flag(k_priv, OPENSSL_EC_NAMED_CURVE);
		EC_KEY_generate_key(k_priv);
		if(verbose) std::cout << "generated key" << std::endl;
		// TODO: password protection
		PEM_write_ECPrivateKey(privf, k_priv, nullptr, nullptr, 0, nullptr, nullptr);
		fclose(privf);
		if(verbose) std::cout << "wrote private key" << std::endl;


		EVP_PKEY * ev_k = EVP_PKEY_new();
		assert(ev_k);
		assert(EVP_PKEY_assign_EC_KEY(ev_k, k_priv) == 1);

		X509 * x = X509_new();
		assert(x);

		X509_set_version(x, 2);
		ASN1_INTEGER_set(X509_get_serialNumber(x), 0);
		X509_gmtime_adj(X509_get_notBefore(x),0);
		// TODO: make expiration date configurable
		X509_gmtime_adj(X509_get_notAfter(x),(long)60*60*24*365*10);

		X509_set_pubkey(x, ev_k);

		X509_NAME * name = X509_get_subject_name(x);
		X509_NAME_add_entry_by_txt(name,"C", MBSTRING_ASC, (unsigned char *) "XX", -1, -1, 0);
		X509_NAME_add_entry_by_txt(name,"ST", MBSTRING_ASC, (unsigned char *) "XX", -1, -1, 0);
		X509_NAME_add_entry_by_txt(name,"L", MBSTRING_ASC, (unsigned char *) "XX", -1, -1, 0);
		X509_NAME_add_entry_by_txt(name,"O", MBSTRING_ASC, (unsigned char *) "I2P Anonymous Network", -1, -1, 0);

		X509_NAME_add_entry_by_txt(name,"OU", MBSTRING_ASC, (unsigned char *) "family", -1, -1, 0);
		X509_NAME_add_entry_by_txt(name,"CN", MBSTRING_ASC, (unsigned char *) cn.c_str(), -1, -1, 0);
		X509_set_issuer_name(x,name);

		if(verbose) std::cout << "signing cert" << std::endl;
		assert(X509_sign(x, ev_k, EVP_sha256()));
		if(verbose) std::cout << "writing private key" << std::endl;
		PEM_write_X509(certf,	x);

		fclose(certf);

		EVP_PKEY_free(ev_k);
		X509_free(x);
		std::cout << "family " << fam << " made" << std::endl;
	}

	if (sign) {
		// sign
		if (!infile.size()) {
			// no router info specified
			std::cerr << "no router keys file specified" << std::endl;
			return 1;
		}
		if (!privkey.size()) {
			// no private key specified
			std::cerr << "no private key specified" << std::endl;
			return 1;
		}

		{
			std::ifstream i;
			i.open(infofile);
			if(!i.is_open()) {
				std::cout << "cannot open " << infofile << std::endl;
				return 1;
			}
		}

		if (verbose) std::cout << "load " << infofile << std::endl;



		PrivateKeys keys;
		{
			std::ifstream fi(infile, std::ifstream::in | std::ifstream::binary);
			if(!fi.is_open()) {
				std::cout << "cannot open " << infile << std::endl;
				return 1;
			}
			fi.seekg (0, std::ios::end);
			size_t len = fi.tellg();
			fi.seekg (0, std::ios::beg);
			uint8_t * k = new uint8_t[len];
			fi.read((char*)k, len);
			if(!keys.FromBuffer(k, len)) {
				std::cout << "invalid key file " << infile << std::endl;
				return 1;
			}
			delete [] k;
		}

		LocalRouterInfo ri(infofile);
		auto ident = ri.GetIdentHash();


		if (verbose) std::cout << "add " << ident.ToBase64() << " to " << fam << std::endl;
		std::string sig;
		if(CreateFamilySignature(fam, ident, privkey, sig)) {
			ri.SetProperty(ROUTER_INFO_PROPERTY_FAMILY, fam);
			ri.SetProperty(ROUTER_INFO_PROPERTY_FAMILY_SIG, sig);
			if (verbose) std::cout << "signed " << sig << std::endl;
			ri.CreateBuffer(keys);
			if(!ri.SaveToFile(infofile)) {
				std::cout << "failed to save to " << infofile << std::endl;
			}
		} else {
			std::cout << "failed to sign router info" << std::endl;
		}
		std::cout << "signed" << std::endl;
	}

	if(verify) {
		if(!infofile.size()) {
			std::cout << "no router info file specified" << std::endl;
			return 1;
		}
		if(!certfile.size()) {
			std::cout << "no family certificate specified" << std::endl;
			return 1;
		}
		auto v = LoadCertificate(certfile);
		if(!v) {
			std::cout << "invalid certificate" << std::endl;
			return 1;
		}

		{
			std::ifstream i;
			i.open(infofile);
			if(!i.is_open()) {
				std::cout << "cannot open " << infofile << std::endl;
				return 1;
			}
		}

		if (verbose) std::cout << "load " << infofile << std::endl;

		LocalRouterInfo ri(infofile);
		auto sig = ri.GetProperty(ROUTER_INFO_PROPERTY_FAMILY_SIG);
		if (ri.GetProperty(ROUTER_INFO_PROPERTY_FAMILY) != fam) {
			std::cout << infofile << " does not belong to " << fam << std::endl;
			return 1;
		}
		auto ident = ri.GetIdentHash();

		uint8_t buf[50];
		size_t len = fam.length();
		memcpy(buf, fam.c_str(), len);
		memcpy(buf + len, (const uint8_t *) ident, 32);
		len += 32;
		uint8_t sigbuf[64];
		Base64ToByteStream(sig.c_str(), sig.length(), sigbuf, 64);
		if(!v->Verify(buf, len, sigbuf)) {
			std::cout << "invalid signature" << std::endl;
			return 1;
		}
		std::cout << "verified" << std::endl;
	}
	return 0;
}