/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _IGNITE_NETWORK_SSL_SSL_GATEWAY
#define _IGNITE_NETWORK_SSL_SSL_GATEWAY

#include <string>
#include <openssl/ssl.h>
#include <openssl/conf.h>
#include <openssl/err.h>

#include <ignite/common/concurrent.h>
#include <ignite/common/dynamic_load_os.h>


namespace ignite
{
    namespace network
    {
        namespace ssl
        {
            /**
             * Functions collection.
             */
            struct SslFunctions
            {
                void *fpSSLeay_version;
                void *fpSSL_CTX_new;
                void *fpSSL_CTX_free;
                void *fpSSL_CTX_set_verify;
                void *fpSSL_CTX_set_verify_depth;
                void *fpSSL_CTX_set_cert_store;
                void *fpSSL_CTX_set_default_verify_paths;
                void *fpSSL_CTX_load_verify_locations;
                void *fpSSL_CTX_use_certificate_chain_file;
                void *fpSSL_CTX_use_RSAPrivateKey_file;
                void *fpSSL_CTX_set_cipher_list;
                void *fpSSL_CTX_ctrl;
                void *fpSSL_get_verify_result;
                void *fpSSL_library_init;
                void *fpSSL_load_error_strings;
                void *fpSSL_get_peer_certificate;
                void *fpSSL_ctrl;
                void *fpSSLv23_client_method;
                void *fpSSL_set_connect_state;
                void *fpSSL_set_bio;
                void *fpSSL_connect;
                void *fpSSL_get_error;
                void *fpSSL_want;
                void *fpSSL_write;
                void *fpSSL_read;
                void *fpSSL_pending;
                void *fpSSL_get_version;
                void *fpSSL_get_fd;
                void *fpSSL_new;
                void *fpSSL_free;
                void *fpOPENSSL_config;
                void *fpX509_STORE_new;
                void *fpX509_STORE_add_cert;
                void *fpd2i_X509;
                void *fpX509_free;
                void *fpBIO_new;
                void *fpBIO_new_ssl_connect;
                void *fpBIO_free_all;
                void *fpBIO_s_mem;
                void *fpBIO_read;
                void *fpBIO_write;
                void *fpBIO_ctrl;
                void *fpERR_get_error;
                void *fpERR_error_string_n;

                void *fpOpenSSL_version;
                void *fpSSL_CTX_set_options;
                void *fpOPENSSL_init_ssl;
                void *fpTLS_client_method;
            };

            /**
             * SSL Gateway abstraction.
             * Used as a factory for secure sockets. Needed for dynamic loading
             * of the SSL libraries.
             */
            class SslGateway
            {
            public:
                /**
                 * Get class instance.
                 * @return SslLibrary instance.
                 */
                static SslGateway& GetInstance();

                /**
                 * Try loading SSL library.
                 */
                void LoadAll();

                /**
                 * Check whether the libraries are loaded.
                 * @return @c true if loaded.
                 */
                bool Loaded() const
                {
                    return inited;
                }

                char* OpenSSL_version_(int type);

                int OPENSSL_init_ssl_(uint64_t opts, const void* settings);

                long SSL_CTX_set_options_(SSL_CTX* ctx, long options);

                long SSL_CTX_ctrl_(SSL_CTX* ctx, int cmd, long larg, void* parg);

                SSL_CTX* SSL_CTX_new_(const SSL_METHOD* meth);

                void SSL_CTX_free_(SSL_CTX* ctx);

                void SSL_CTX_set_verify_(SSL_CTX* ctx, int mode, int (*callback)(int, X509_STORE_CTX*));

                void SSL_CTX_set_verify_depth_(SSL_CTX* ctx, int depth);

                void SSL_CTX_set_cert_store_(SSL_CTX* ctx, X509_STORE* store);

                int SSL_CTX_set_default_verify_paths_(SSL_CTX* ctx);

                int SSL_CTX_load_verify_locations_(SSL_CTX* ctx, const char* cAfile, const char* cApath);

                int SSL_CTX_use_certificate_chain_file_(SSL_CTX* ctx, const char* file);

                int SSL_CTX_use_RSAPrivateKey_file_(SSL_CTX* ctx, const char* file, int type);

                int SSL_CTX_set_cipher_list_(SSL_CTX* ctx, const char* str);

                long SSL_get_verify_result_(const SSL* s);

                int SSL_library_init_();

                void SSL_load_error_strings_();

                X509* SSL_get_peer_certificate_(const SSL* s);

                long SSL_ctrl_(SSL* s, int cmd, long larg, void* parg);

                long SSL_set_tlsext_host_name_(SSL* s, const char* name);

                void SSL_set_connect_state_(SSL* s);

                int SSL_connect_(SSL* s);

                void SSL_set_bio_(SSL* s, BIO* rbio, BIO* wbio);

                int SSL_get_error_(const SSL* s, int ret);

                int SSL_want_(const SSL* s);

                int SSL_write_(SSL* s, const void* buf, int num);

                int SSL_read_(SSL* s, void* buf, int num);

                int SSL_pending_(const SSL* ssl);

                const char* SSL_get_version_(const SSL* ssl);

                int SSL_get_fd_(const SSL* ssl);

                SSL* SSL_new_(SSL_CTX* ctx);

                void SSL_free_(SSL* ssl);

                const SSL_METHOD* SSLv23_client_method_();

                const SSL_METHOD* TLS_client_method_();

                void OPENSSL_config_(const char* configName);

                X509_STORE* X509_STORE_new_();

                int X509_STORE_add_cert_(X509_STORE* ctx, X509* cert);

                X509* d2i_X509_(X509** cert, const unsigned char** ppin, long length);

                void X509_free_(X509* cert);

                BIO* BIO_new_(const BIO_METHOD* method);

                BIO* BIO_new_ssl_connect_(SSL_CTX* ctx);

                void BIO_free_all_(BIO* a);

                const BIO_METHOD* BIO_s_mem_();

                int BIO_read_(BIO* b, void* data, int len);

                int BIO_write_(BIO* b, const void *data, int len);

                int BIO_pending_(BIO* b);

                long BIO_ctrl_(BIO* bp, int cmd, long larg, void* parg);

                long BIO_get_ssl_(BIO* bp, SSL** ssl);

                long BIO_set_nbio_(BIO* bp, long n);

                long BIO_set_conn_hostname_(BIO* bp, const char* name);

                unsigned long ERR_get_error_();

                void ERR_error_string_n_(unsigned long e, char* buf, size_t len);

            private:
                /**
                 * Constructor.
                 */
                SslGateway();

                /**
                 * Destructor.
                 */
                ~SslGateway();

                /**
                 * Unload all SSL symbols.
                 */
                void UnloadAll();

                /**
                 * Load SSL library.
                 * @param name Name.
                 * @param homeDir OpenSSL home directory.
                 * @return Module.
                 */
                static common::dynamic::Module LoadSslLibrary(const std::string& name, const std::string& homeDir);

                /**
                 * Load all SSL libraries.
                 */
                void LoadSslLibraries();

                /**
                 * Try load SSL libraries
                 * @param homeDir OpenSSL home directory.
                 * @return @c true on success and @c false if not.
                 */
                bool TryLoadSslLibraries(const std::string& homeDir);

                /**
                 * Load mandatory SSL methods.
                 *
                 * @throw IgniteError if can not load one of the functions.
                 */
                void LoadMandatoryMethods();

                /**
                 * Try load SSL method.
                 *
                 * @param name Name.
                 * @return Method pointer.
                 */
                void* TryLoadSslMethod(const char* name);

                /**
                 * Load SSL method.
                 *
                 * @param name Name.
                 * @return Method pointer.
                 *
                 * @throw IgniteError if the method is not present.
                 */
                void* LoadSslMethod(const char* name);

                /** Indicates whether the library was inited. */
                bool inited;

                /** Critical section to prevent multiple instance creation. */
                common::concurrent::CriticalSection initCs;

                /** libeay32 module. */
                common::dynamic::Module libeay32;

                /** ssleay32 module. */
                common::dynamic::Module ssleay32;

                /** libcrypto module. */
                common::dynamic::Module libcrypto;

                /** libssl module. */
                common::dynamic::Module libssl;

                /** Functions. */
                SslFunctions functions;
            };
        }
    }
}

#endif //_IGNITE_NETWORK_SSL_SSL_GATEWAY