/*! @file

    @id $Id$
*/
//       1         2         3         4         5         6         7         8
// 45678901234567890123456789012345678901234567890123456789012345678901234567890

#ifndef __OPENSSL_ENGINE_HXX__
#define __OPENSSL_ENGINE_HXX__
#include <openssl/opensslv.h>
#ifndef OPENSSL_VERSION_NUMBER
#  error OpenSSL Version Number not Found
#elif OPENSSL_VERSION_NUMBER < 0x10000000L
#  define OPENSSL_0
#  define OPENSSL_V0_CONST
#else
#  define OPENSSL_1
#  define OPENSSL_V0_CONST const
#endif

#undef DATADIR
#include <openssl/engine.h>
#include <map>
#include <string>

#ifndef OPENSSL_CHECK
#include <stdexcept>
#include <sstream>
#if __GNUC__ >= 2
//! Macro for internal OpenSSL checks.
/*! You can define a different implementation in your compile call */
#define OPENSSL_CHECK(X) if (!X) {ERR_load_ENGINE_strings(); std::stringstream ss; for (unsigned int err(0); err=ERR_get_error();) ss<<"Error: "<<ERR_error_string(err, 0)<<"; "; ss<<"Command "<<#X<<" failed in function "<<__PRETTY_FUNCTION__<<" in file "<<__FILE__<<":"<<__LINE__; throw std::runtime_error(ss.str());}
#else
#define OPENSSL_CHECK(X) if (!X) {ERR_load_ENGINE_strings(); std::stringstream ss; for (unsigned int err(0); err=ERR_get_error();) ss<<"Error: "<<ERR_error_string(err, 0)<<"; "; ss<<"Command "<<#X<<" failed in file "<<__FILE__<<":"<<__LINE__; throw std::runtime_error(ss.str());}
#endif
#endif
#ifndef OPENSSL_LOG
  #include <iostream>
  #if __GNUC__ >= 2
    //! Openssl Logging
    /*! If you want to change openssl logging mechanism, just
        redefine your own OPENSSL_LOG macro before <code>#include
        &lt;openssl.hxx&gt;</code>. Define it empty for no logging at
        all. By default logs to <code>std::clog</code>. */
    #define OPENSSL_LOG(X) std::clog<<X<<" @ "<<__PRETTY_FUNCTION__<<std::endl
  #else
    //! Openssl Logging
    /*! If you want to change openssl logging mechanism, just
        redefine your own OPENSSL_LOG macro before <code>#include
        &lt;openssl.hxx&gt;</code>. Define it empty for no logging at
        all. By default logs to <code>std::clog</code>. */
    #define OPENSSL_LOG(X) std::clog<<X<<" @ "<<__FILE__<<__LINE__<<std::endl
  #endif
#endif

//! @addtogroup gopenssl
//@{
//! @defgroup opensslengine OpenSSL Engine C++ Wrapper
//@}

namespace openssl {

  //! @addtogroup opensslengine
  //@{

  //! Abstract Engine Base
  /*! Inherit and overwrite to implement your own Engine.

      Then in the scope where you need it, register your engine:
      <code>
      openssl::RegisterEngine myEngine(new MyEngine);
      </code> */
  class Engine {
      
    public:
      
      Engine(): _e(ENGINE_new()) {
        OPENSSL_LOG("log");
      }
      virtual ~Engine() {
        OPENSSL_LOG("log");
        OPENSSL_CHECK(ENGINE_free(_e));
      }
      virtual const char* id() = 0;
      virtual const char* name() = 0;
      virtual int init() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual int finish() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual int ctrl(int, long, void*, void(*)()) {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual int cmd() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual EVP_PKEY* pubkey(const char*, UI_METHOD*, void*) {
        OPENSSL_LOG("log");
        return 0;
      }
      virtual EVP_PKEY* privkey(const char*, UI_METHOD*, void*) {
        OPENSSL_LOG("log");
        return 0;
      }
      virtual int rsaEncrypt() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual int rsaDecrypt() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual std::string rsaSign(const std::string&, unsigned int) {
        OPENSSL_LOG("log");
        throw std::runtime_error("rsaSign not implemented");
      }
      virtual int rsaVerify() {
        OPENSSL_LOG("log");
        return 1;
      }
      virtual int rsaFinish() {
        OPENSSL_LOG("log");
        return 1;
      }

    protected:

      friend class EngineMapper;
      ENGINE* _e;
      
  };

  class EngineMapper {
      
    public:
      
      static void add(Engine *e) {
        OPENSSL_LOG("log");
        _prototypes[e->id()] = e;
        _map[e->_e] = e;
        OPENSSL_CHECK(ENGINE_set_id(e->_e, e->id()));
        OPENSSL_CHECK(ENGINE_set_name(e->_e, e->name()));
        OPENSSL_CHECK(ENGINE_set_destroy_function(e->_e, EngineMapper::destroy));
        OPENSSL_CHECK(ENGINE_set_init_function(e->_e, EngineMapper::init));
        OPENSSL_CHECK(ENGINE_set_finish_function(e->_e, EngineMapper::finish));
        OPENSSL_CHECK(ENGINE_set_ctrl_function(e->_e, EngineMapper::ctrl));
        //OPENSSL_CHECK(ENGINE_set_cmd_defns(e->_e, EngineMapper::cmd));
#ifndef OPENSSL_NO_RSA
        OPENSSL_CHECK(ENGINE_set_RSA(e->_e, rsa()));
#endif
#ifndef OPENSSL_NO_DSA
        // OPENSSL_CHECK(ENGINE_set_DSA(e->_e, DSA_get_default_method()));
#endif
#ifndef OPENSSL_NO_DH
        // OPENSSL_CHECK(ENGINE_set_DH(e->_e, DSA_get_default_method()));
#endif
        // OPENSSL_CHECK(ENGINE_set_RAND(e->_e, rand()));
        OPENSSL_CHECK(ENGINE_set_load_pubkey_function(e->_e, pubkey));
        OPENSSL_CHECK(ENGINE_set_load_privkey_function(e->_e, privkey));
        OPENSSL_CHECK(ENGINE_init(e->_e));
        OPENSSL_CHECK(ENGINE_add(e->_e));
      }

      static void remove(Engine *e) {
        OPENSSL_CHECK(ENGINE_remove(e->_e));
        OPENSSL_CHECK(ENGINE_finish(e->_e));
        _map.erase(e->_e);
        delete e;
      }
      
    private:
      
      static int destroy(ENGINE* e) {
        OPENSSL_LOG("log");
        return 1;
      }
      static int init(ENGINE* e) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(e));
        return it!=_map.end()?it->second->init():0;
      }
      static int finish(ENGINE* e) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(e));
        return it!=_map.end()?it->second->finish():0;
      }
      static int ctrl(ENGINE* e, int cmd, long i, void* p, void(*f)()) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(e));
        return it!=_map.end()?it->second->ctrl(cmd, i, p, f):0;
      }
      static EVP_PKEY* pubkey(ENGINE* e, const char* c, UI_METHOD* u, void* d) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(e));
        return it!=_map.end()?it->second->pubkey(c, u, d):0;
      }
      static EVP_PKEY* privkey(ENGINE* e, const char* c, UI_METHOD* u, void* d) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(e));
        return it!=_map.end()?it->second->privkey(c, u, d):0;
      }
      static int rsaEncrypt(int flen,const unsigned char *from,
			    unsigned char *to,
			    RSA *rsa, int padding) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(rsa->engine));
        return it!=_map.end()?it->second->rsaEncrypt():0;
      }
      static int rsaDecrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(rsa->engine));
        return it!=_map.end()?it->second->rsaDecrypt():0;
      }
      static int rsaSign(int type, const unsigned char *from,
                         unsigned int flen,
                         unsigned char *to,
                         unsigned int*tlen,
                         const RSA *rsa) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(rsa->engine));
        if (it==_map.end()) return 0;
        try {
          std::string res(it->second->rsaSign
                          (std::string((const char*)from, flen),
                           type));
          OPENSSL_LOG("to="<<(void*)to<<"; len="<<*tlen);
          OPENSSL_LOG("siglen="<<res.size());
          *tlen = res.size();
          std::copy(res.begin(), res.end(), to);
          return 1;
        } catch (const std::exception& e) {
          OPENSSL_LOG("ERROR: "<<e.what());
          return 0;
        }
      }
      static int rsaVerify(int, const unsigned char*,
                           unsigned int,  OPENSSL_V0_CONST unsigned char*,
                           unsigned int, const RSA* rsa) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(rsa->engine));
        return it!=_map.end()?it->second->rsaVerify():0;
      }
      static int rsaFinish(RSA *rsa) {
        OPENSSL_LOG("log");
        Map::iterator it(_map.find(rsa->engine));
        return it!=_map.end()?it->second->rsaFinish():0;
      }
      
    protected:
      
      static RSA_METHOD* rsa() {
        OPENSSL_LOG("log");
	static RSA_METHOD ops;
        if (!ops.rsa_priv_enc) {
          ops = *RSA_get_default_method();
          ops.rsa_pub_enc = rsaEncrypt;
          ops.rsa_priv_dec = rsaDecrypt;
          // a.k.a Verify/Sign. actLibrary just allows the proper functions
          // and has this 'backdoor' closed. Breaks 'rsautl', sadly.
          ops.rsa_pub_dec = NULL;
          ops.rsa_priv_enc = NULL;
          ops.rsa_sign = rsaSign;
          ops.rsa_verify = rsaVerify;
          ops.finish = rsaFinish;
        }
	return &ops;
      }

    private:

      typedef std::map<ENGINE*, Engine*> Map;
      static Map _map;
      static std::map<std::string, Engine*> _prototypes;
  };

  //! Scoped Engine Registry
  /*! Engine will be deregistered and freed at destruction */
  template <class ENGINE=Engine> class RegisterEngine {
    public:
      RegisterEngine(ENGINE* e = 0): _e(e) {
        if (_e) EngineMapper::add(_e);
      }
      ~RegisterEngine() {
        if (_e) EngineMapper::remove(_e);
      }
      RegisterEngine& operator=(ENGINE* e) {
        if (_e) EngineMapper::remove(_e);
        _e = e;
        if (_e) EngineMapper::add(_e);
        return *this;
      }
      operator ENGINE*() {
        return _e;
      }
       ENGINE* operator->() {
        return _e;
      }
       ENGINE& operator*() {
        return *_e;
      }
    private:
      ENGINE* _e;
  };

  //@}
}
#endif