/*
  Copyright (c) 2007-2019 by Jakob Schröter <js@camaya.net>
  This file is part of the gloox library. http://camaya.net/gloox

  This software is distributed under a license. The full license
  agreement can be found in the file LICENSE in this distribution.
  This software may not be copied, modified, sold or distributed
  other than expressed in the named license agreement.

  This software is distributed without any warranty.
*/



#ifndef TLSBASE_H__
#define TLSBASE_H__

#include "gloox.h"
#include "mutex.h"
#include "tlshandler.h"

namespace gloox
{

  /**
   * @brief An abstract base class for TLS implementations.
   *
   * @author Jakob Schröter <js@camaya.net>
   * @since 0.9
   */
  class GLOOX_API TLSBase
  {
    public:
      /**
       * Constructor.
       * @param th The TLSHandler to handle TLS-related events.
       * @param server The server to use in certificate verification.
       */
      TLSBase( TLSHandler* th, const std::string server )
        : m_handler( th ), m_server( server ), m_secure( false ), m_valid( false ), m_initLib( true )
      {}

      /**
       * Virtual destructor.
       */
      virtual ~TLSBase() {}

      /**
       * Initializes the TLS module. This function must be called (and execute successfully)
       * before the module can be used.
       * @param clientKey The absolute path to the user's private key in PEM format.
       * @param clientCerts A path to a certificate bundle in PEM format.
       * @param cacerts A list of absolute paths to CA root certificate files in PEM format.
       * @return @b False if initialization failed, @b true otherwise.
       * @since 1.0
       */
      virtual bool init( const std::string& clientKey = EmptyString,
                         const std::string& clientCerts = EmptyString,
                         const StringList& cacerts = StringList() ) = 0;

      /**
       * Enables/disables initialization of the underlying TLS library. By default,
       * initialization is performed. You may want to switch it off if the TLS library
       * is used elsewhere in your application as well and you have no control over the
       * initialization.
       * @param init Whether or not to intialize the underlying TLS library.
       */
      void setInitLib( bool init ) { m_initLib = init; }

      /**
       * Use this function to feed unencrypted data to the encryption implementation.
       * The encrypted result will be pushed to the TLSHandler's handleEncryptedData() function.
       * @param data The data to encrypt.
       * @return Whether or not the data was used successfully.
       */
      virtual bool encrypt( const std::string& data ) = 0;

      /**
       * Use this function to feed encrypted data or received handshake data to the
       * encryption implementation. Handshake data will be eaten, unencrypted data
       * will be pushed to the TLSHandler's handleDecryptedData() function.
       * @param data The data to decrypt.
       * @return The number of bytes used from the input.
       */
      virtual int decrypt( const std::string& data ) = 0;

      /**
       * This function performs internal cleanup and will be called after a failed handshake attempt.
       */
      virtual void cleanup() = 0;

      /**
       * This functiopn performs the TLS handshake. Handshake data from the server side should be
       * fed in using decrypt(). Handshake data that is to be sent to the other side is pushed through
       * TLSBase's handleEncryptedData().
       * @return @b True if the handshake was successful or if more input is needed, @b false if the
       * handshake failed.
       */
      virtual bool handshake() = 0;

      /**
       * Returns the state of the encryption.
       * @return The state of the encryption.
       */
      virtual bool isSecure() const { return m_secure; }

      /**
       * This function indicates whether the underlying TLS implementation supports channel binding (used in e.g. SASL SCRAM-SHA-1-PLUS).
       * @return @b True if channel binding is supported, @b false otherwise.
       */
      virtual bool hasChannelBinding() const { return false; }

      /**
       * Returns the channel binding data for the established connection.
       * @return The channel binding data, if any, or the empty string.
       */
      virtual const std::string channelBinding() const { return EmptyString; }

      /**
       * Use this function to set a number of trusted root CA certificates which shall be
       * used to verify a servers certificate.
       * @param cacerts A list of absolute paths to CA root certificate files in PEM format.
       */
      virtual void setCACerts( const StringList& cacerts ) = 0;

      /**
       * This function is used to retrieve certificate and connection info of a encrypted connection.
       * @return Certificate information.
       */
      virtual const CertInfo& fetchTLSInfo() const { return m_certInfo; }

      /**
       * Use this function to set the user's certificate and private key. The certificate will
       * be presented to the server upon request and can be used for SASL EXTERNAL authentication.
       * The user's certificate file should be a bundle of more than one certificate in PEM format.
       * The first one in the file should be the user's certificate, each cert following that one
       * should have signed the previous one.
       * @note These certificates are not necessarily the same as those used to verify the server's
       * certificate.
       * @param clientKey The absolute path to the user's private key in PEM format.
       * @param clientCerts A path to a certificate bundle in PEM format.
       */
      virtual void setClientCert( const std::string& clientKey, const std::string& clientCerts ) = 0;

    protected:
      TLSHandler* m_handler;
      StringList m_cacerts;
      std::string m_clientKey;
      std::string m_clientCerts;
      std::string m_server;
      CertInfo m_certInfo;
      util::Mutex m_mutex;
      bool m_secure;
      bool m_valid;
      bool m_initLib;

  };

}

#endif // TLSBASE_H__
