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 /*
  *          Copyright Andrey Semashev 2007 - 2015.
  * Distributed under the Boost Software License, Version 1.0.
  *    (See accompanying file LICENSE_1_0.txt or copy at
  *          http://www.boost.org/LICENSE_1_0.txt)
  */
 /*!
  * \file   event_log_backend.hpp
  * \author Andrey Semashev
  * \date   07.11.2008
  *
  * The header contains a logging sink backend that uses Windows NT event log API
  * for signaling application events.
  */
 
 #ifndef BOOST_LOG_SINKS_EVENT_LOG_BACKEND_HPP_INCLUDED_
 #define BOOST_LOG_SINKS_EVENT_LOG_BACKEND_HPP_INCLUDED_
 
 #include <boost/log/detail/config.hpp>
 
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #pragma once
 #endif
 
 #ifndef BOOST_LOG_WITHOUT_EVENT_LOG
 
 #include <map>
 #include <vector>
 #include <string>
 #include <iosfwd>
 #include <boost/filesystem/path.hpp>
 #include <boost/log/detail/light_function.hpp>
 #include <boost/log/detail/parameter_tools.hpp>
 #include <boost/log/attributes/attribute_value_set.hpp>
 #include <boost/log/keywords/message_file.hpp>
 #include <boost/log/keywords/log_name.hpp>
 #include <boost/log/keywords/log_source.hpp>
 #include <boost/log/keywords/registration.hpp>
 #include <boost/log/keywords/target.hpp>
 #include <boost/log/sinks/basic_sink_backend.hpp>
 #include <boost/log/sinks/frontend_requirements.hpp>
 #include <boost/log/sinks/attribute_mapping.hpp>
 #include <boost/log/sinks/event_log_constants.hpp>
 #include <boost/log/core/record_view.hpp>
 #include <boost/log/expressions/formatter.hpp>
 #include <boost/log/detail/header.hpp>
 
 namespace boost {
 
 BOOST_LOG_OPEN_NAMESPACE
 
 namespace sinks {
 
 namespace event_log {
 
     //! Event log source registration modes
     enum registration_mode
     {
         never,      //!< Never register event source, even if it's not registered
         on_demand,  //!< Register if the source is not registered yet
         forced      //!< Register always, event if the source is already registered
     };
 
     /*!
      * \brief Straightforward event type mapping
      *
      * This type of mapping assumes that attribute with a particular name always
      * provides values that map directly onto the native event types. The mapping
      * simply returns the extracted attribute value converted to the native event type.
      */
     template< typename AttributeValueT = int >
     class direct_event_type_mapping :
         public basic_direct_mapping< event_type, AttributeValueT >
     {
         //! Base type
         typedef basic_direct_mapping< event_type, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit direct_event_type_mapping(attribute_name const& name) :
             base_type(name, info)
         {
         }
     };
 
     /*!
      * \brief Customizable event type mapping
      *
      * The class allows to setup a custom mapping between an attribute and native event types.
      * The mapping should be initialized similarly to the standard \c map container, by using
      * indexing operator and assignment.
      */
     template< typename AttributeValueT = int >
     class custom_event_type_mapping :
         public basic_custom_mapping< event_type, AttributeValueT >
     {
         //! Base type
         typedef basic_custom_mapping< event_type, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit custom_event_type_mapping(attribute_name const& name) :
             base_type(name, info)
         {
         }
     };
 
     /*!
      * \brief Straightforward event ID mapping
      *
      * This type of mapping assumes that attribute with a particular name always
      * provides values that map directly onto the event identifiers. The mapping
      * simply returns the extracted attribute value converted to the event ID.
      */
     template< typename AttributeValueT = int >
     class direct_event_id_mapping :
         public basic_direct_mapping< event_id, AttributeValueT >
     {
         //! Base type
         typedef basic_direct_mapping< event_id, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit direct_event_id_mapping(attribute_name const& name) :
             base_type(name, make_event_id(0))
         {
         }
     };
 
     /*!
      * \brief Customizable event ID mapping
      *
      * The class allows to setup a custom mapping between an attribute and event identifiers.
      * The mapping should be initialized similarly to the standard \c map container, by using
      * indexing operator and assignment.
      */
     template< typename AttributeValueT = int >
     class custom_event_id_mapping :
         public basic_custom_mapping< event_id, AttributeValueT >
     {
         //! Base type
         typedef basic_custom_mapping< event_id, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit custom_event_id_mapping(attribute_name const& name) :
             base_type(name, make_event_id(0))
         {
         }
     };
 
     /*!
      * \brief Straightforward event category mapping
      *
      * This type of mapping assumes that attribute with a particular name always
      * provides values that map directly onto the event categories. The mapping
      * simply returns the extracted attribute value converted to the event category.
      */
     template< typename AttributeValueT = int >
     class direct_event_category_mapping :
         public basic_direct_mapping< event_category, AttributeValueT >
     {
         //! Base type
         typedef basic_direct_mapping< event_category, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit direct_event_category_mapping(attribute_name const& name) :
             base_type(name, make_event_category(0))
         {
         }
     };
 
     /*!
      * \brief Customizable event category mapping
      *
      * The class allows to setup a custom mapping between an attribute and event categories.
      * The mapping should be initialized similarly to the standard \c map container, by using
      * indexing operator and assignment.
      */
     template< typename AttributeValueT = int >
     class custom_event_category_mapping :
         public basic_custom_mapping< event_category, AttributeValueT >
     {
         //! Base type
         typedef basic_custom_mapping< event_category, AttributeValueT > base_type;
 
     public:
         /*!
          * Constructor
          *
          * \param name Attribute name
          */
         explicit custom_event_category_mapping(attribute_name const& name) :
             base_type(name, make_event_category(0))
         {
         }
     };
 
     /*!
      * \brief An event composer
      *
      * This class is a function object that extracts event identifier from the attribute values set
      * and formats insertion strings for the particular event. Each insertion string is formatted with
      * a distinct formatter, which can be created just like regular sinks formatters.
      *
      * Before using, the composer must be initialized with the following information:
      * \li Event identifier extraction logic. One can use \c basic_direct_event_id_mapping or
      *     \c basic_custom_event_id_mapping classes in order to create such extractor and pass it
      *     to the composer constructor.
      * \li Event identifiers and insertion string formatters. The composer provides the following
      *     syntax to provide this information:
      *
      *     \code
      *     event_composer comp;
      *     comp[MY_EVENT_ID1] % formatter1 % ... % formatterN;
      *     comp[MY_EVENT_ID2] % formatter1 % ... % formatterN;
      *     ...
      *     \endcode
      *
      *     The event identifiers in square brackets are provided by the message compiler generated
      *     header (the actual names are specified in the .mc file). The formatters represent
      *     the insertion strings that will be used to replace placeholders in event messages,
      *     thus the number and the order of the formatters must correspond to the message definition.
      */
     template< typename CharT >
     class BOOST_LOG_API basic_event_composer
     {
     public:
         //! Character type
         typedef CharT char_type;
         //! String type to be used as a message text holder
         typedef std::basic_string< char_type > string_type;
 
         //! Event identifier mapper type
         typedef boost::log::aux::light_function< event_id (record_view const&) > event_id_mapper_type;
 
         //! Type of an insertion composer (a formatter)
         typedef basic_formatter< char_type > formatter_type;
         //! Type of the composed insertions list
         typedef std::vector< string_type > insertion_list;
 
     private:
         //! \cond
 
         //! The class that implements formatting of insertion strings
         class insertion_composer;
 
         //! Type of the events map
         typedef std::map< event_id, insertion_composer > event_map;
 
         //! A smart reference that puts formatters into the composer
         class event_map_reference;
         friend class event_map_reference;
         class event_map_reference
         {
         private:
             //! Event identifier
             event_id m_ID;
             //! A reference to the object that created the reference
             basic_event_composer< char_type >& m_Owner;
             //! A hint for the owner to optimize insertion
             insertion_composer* m_Composer;
 
         public:
             //! Initializing constructor
             explicit event_map_reference(event_id id, basic_event_composer< char_type >& owner) :
                 m_ID(id),
                 m_Owner(owner),
                 m_Composer(0)
             {
             }
             //! The operator puts the formatter into the composer
             template< typename FormatterT >
             event_map_reference& operator% (FormatterT const& fmt)
             {
                 m_Composer = m_Owner.add_formatter(m_ID, m_Composer, formatter_type(fmt));
                 return *this;
             }
         };
 
         //! \endcond
 
     private:
         //! The mapper that will extract the event identifier
         event_id_mapper_type m_EventIDMapper;
         //! The map of event identifiers and their insertion composers
         event_map m_EventMap;
 
     public:
         /*!
          * Default constructor. Creates an empty map of events.
          *
          * \param id_mapper An event identifier mapping function that will be used to extract event ID from attribute values
          */
         explicit basic_event_composer(event_id_mapper_type const& id_mapper);
         /*!
          * Copy constructor. Performs a deep copy of the object.
          */
         basic_event_composer(basic_event_composer const& that);
         /*!
          * Destructor
          */
         ~basic_event_composer();
 
         /*!
          * Assignment. Provides strong exception guarantee.
          */
         basic_event_composer& operator= (basic_event_composer that);
         /*!
          * Swaps \c *this and \c that objects.
          */
         void swap(basic_event_composer& that);
         /*!
          * Initiates creation of a new event description. The result of the operator can be used to
          * add formatters for insertion strings construction. The returned reference type is implementation detail.
          *
          * \param id Event identifier.
          */
         event_map_reference operator[] (event_id id);
         /*!
          * Initiates creation of a new event description. The result of the operator can be used to
          * add formatters for insertion strings construction. The returned reference type is implementation detail.
          *
          * \param id Event identifier.
          */
         event_map_reference operator[] (int id);
         /*!
          * Event composition operator. Extracts an event identifier from the attribute values by calling event ID mapper.
          * Then runs all formatters that were registered for the event with the extracted ID. The results of formatting
          * are returned in the \a insertions parameter.
          *
          * \param rec Log record view
          * \param insertions A sequence of formatted insertion strings
          * \return An event identifier that was extracted from \c attributes
          */
         event_id operator() (record_view const& rec, insertion_list& insertions) const;
 
     private:
 #ifndef BOOST_LOG_DOXYGEN_PASS
         //! Adds a formatter to the insertion composers list
         insertion_composer* add_formatter(event_id id, insertion_composer* composer, formatter_type const& fmt);
 #endif // BOOST_LOG_DOXYGEN_PASS
     };
 
 #ifdef BOOST_LOG_USE_CHAR
     typedef basic_event_composer< char > event_composer;          //!< Convenience typedef for narrow-character logging
 #endif
 #ifdef BOOST_LOG_USE_WCHAR_T
     typedef basic_event_composer< wchar_t > wevent_composer;      //!< Convenience typedef for wide-character logging
 #endif
 
 } // namespace event_log
 
 /*!
  * \brief An implementation of a simple logging sink backend that emits events into Windows NT event log
  *
  * The sink uses Windows NT 5 (Windows 2000) and later event log API to emit events
  * to an event log. The sink acts as an event source in terms of the API, it implements all needed resources
  * and source registration in the Windows registry that is needed for the event delivery.
  *
  * The backend performs message text formatting. The composed text is then passed as the first
  * and only string parameter of the event. The resource embedded into the backend describes the event
  * so that the parameter is inserted into the event description text, thus making it visible
  * in the event log.
  *
  * The backend allows to customize mapping of application severity levels to the native Windows event types.
  * This allows to write portable code even if OS-specific sinks, such as this one, are used.
  *
  * \note Since the backend registers itself into Windows registry as the resource file that contains
  *       event description, it is important to keep the library binary in a stable place of the filesystem.
  *       Otherwise Windows might not be able to load event resources from the library and display
  *       events correctly.
  *
  * \note It is known that Windows is not able to find event resources in the application executable,
  *       which is linked against the static build of the library. Users are advised to use dynamic
  *       builds of the library to solve this problem.
  */
 template< typename CharT >
 class basic_simple_event_log_backend :
     public basic_formatted_sink_backend< CharT, concurrent_feeding >
 {
     //! Base type
     typedef basic_formatted_sink_backend< CharT, concurrent_feeding > base_type;
     //! Implementation type
     struct implementation;
 
 public:
     //! Character type
     typedef typename base_type::char_type char_type;
     //! String type to be used as a message text holder
     typedef typename base_type::string_type string_type;
 
     //! Mapper type for the event type
     typedef boost::log::aux::light_function< event_log::event_type (record_view const&) > event_type_mapper_type;
 
 private:
     //! Pointer to the backend implementation that hides various types from windows.h
     implementation* m_pImpl;
 
 public:
     /*!
      * Default constructor. Registers event source with name based on the application
      * executable file name in the Application log. If such a registration is already
      * present, it is not overridden.
      */
     BOOST_LOG_API basic_simple_event_log_backend();
     /*!
      * Constructor. Registers event log source with the specified parameters.
      * The following named parameters are supported:
      *
      * \li \c target - Specifies an UNC path to the remote server which log records should be sent to.
      *     The local machine will be used to process log records, if not specified.
      * \li \c log_name - Specifies the log in which the source should be registered.
      *     The result of \c get_default_log_name is used, if the parameter is not specified.
      * \li \c log_source - Specifies the source name. The result of \c get_default_source_name
      *     is used, if the parameter is not specified.
      * \li \c registration - Specifies the event source registration mode in the Windows registry.
      *     Can have values of the \c registration_mode enum. Default value: \c on_demand.
      *
      * \param args A set of named parameters.
      */
 #ifndef BOOST_LOG_DOXYGEN_PASS
     BOOST_LOG_PARAMETRIZED_CONSTRUCTORS_CALL(basic_simple_event_log_backend, construct)
 #else
     template< typename... ArgsT >
     explicit basic_simple_event_log_backend(ArgsT... const& args);
 #endif
 
     /*!
      * Destructor. Unregisters event source. The log source description is not removed from the Windows registry.
      */
     BOOST_LOG_API ~basic_simple_event_log_backend();
 
     /*!
      * The method installs the function object that maps application severity levels to WinAPI event types
      */
     BOOST_LOG_API void set_event_type_mapper(event_type_mapper_type const& mapper);
 
     /*!
      * \returns Default log name: Application
      */
     BOOST_LOG_API static string_type get_default_log_name();
     /*!
      * \returns Default log source name that is based on the application executable file name and the sink name
      */
     BOOST_LOG_API static string_type get_default_source_name();
 
     /*!
      * The method puts the formatted message to the event log
      */
     BOOST_LOG_API void consume(record_view const& rec, string_type const& formatted_message);
 
 private:
 #ifndef BOOST_LOG_DOXYGEN_PASS
     //! Constructs backend implementation
     template< typename ArgsT >
     void construct(ArgsT const& args)
     {
         construct(
             args[keywords::target | string_type()],
             args[keywords::log_name || &basic_simple_event_log_backend::get_default_log_name],
             args[keywords::log_source || &basic_simple_event_log_backend::get_default_source_name],
             args[keywords::registration | event_log::on_demand]);
     }
     BOOST_LOG_API void construct(
         string_type const& target,
         string_type const& log_name,
         string_type const& source_name,
         event_log::registration_mode reg_mode);
 #endif // BOOST_LOG_DOXYGEN_PASS
 };
 
 /*!
  * \brief An implementation of a logging sink backend that emits events into Windows NT event log
  *
  * The sink uses Windows NT 5 (Windows 2000) and later event log API to emit events
  * to an event log. The sink acts as an event source. Unlike \c basic_simple_event_log_backend,
  * this sink backend allows users to specify the custom event message file and supports
  * mapping attribute values onto several insertion strings. Although it requires considerably
  * more scaffolding than the simple backend, this allows to support localizable event descriptions.
  *
  * Besides the file name of the module with event resources, the backend provides the following
  * customizations:
  * \li Remote server UNC address, log name and source name. These parameters have similar meaning
  *     to \c basic_simple_event_log_backend.
  * \li Event type and category mappings. These are function object that allow to map attribute
  *     values to the according event parameters. One can use mappings in the \c event_log namespace.
  * \li Event composer. This function object extracts event identifier and formats string insertions,
  *     that will be used by the API to compose the final event message text.
  */
 template< typename CharT >
 class basic_event_log_backend :
     public basic_sink_backend< synchronized_feeding >
 {
     //! Base type
     typedef basic_sink_backend< synchronized_feeding > base_type;
     //! Implementation type
     struct implementation;
 
 public:
     //! Character type
     typedef CharT char_type;
     //! String type
     typedef std::basic_string< char_type > string_type;
     //! Type of the composed insertions list
     typedef std::vector< string_type > insertion_list;
 
     //! Mapper type for the event type
     typedef boost::log::aux::light_function< event_log::event_type (record_view const&) > event_type_mapper_type;
     //! Mapper type for the event category
     typedef boost::log::aux::light_function< event_log::event_category (record_view const&) > event_category_mapper_type;
     //! Event composer type
     typedef boost::log::aux::light_function< event_log::event_id (record_view const&, insertion_list&) > event_composer_type;
 
 private:
     //! Pointer to the backend implementation that hides various types from windows.h
     implementation* m_pImpl;
 
 public:
     /*!
      * Constructor. Registers event source with name based on the application
      * executable file name in the Application log. If such a registration is already
      * present, it is not overridden.
      */
     template< typename T >
     explicit basic_event_log_backend(std::basic_string< T > const& message_file_name)
     {
         construct(keywords::message_file = message_file_name);
     }
     /*!
      * Constructor. Registers event source with name based on the application
      * executable file name in the Application log. If such a registration is already
      * present, it is not overridden.
      */
     explicit basic_event_log_backend(filesystem::path const& message_file_name)
     {
         construct(keywords::message_file = message_file_name);
     }
     /*!
      * Constructor. Registers event log source with the specified parameters.
      * The following named parameters are supported:
      *
      * \li \c message_file - Specifies the file name that contains resources that
      *     describe events and categories. This parameter is mandatory unless \c registration is \c never.
      * \li \c target - Specifies an UNC path to the remote server to which log records should be sent to.
      *     The local machine will be used to process log records, if not specified.
      * \li \c log_name - Specifies the log in which the source should be registered.
      *     The result of \c get_default_log_name is used, if the parameter is not specified.
      * \li \c log_source - Specifies the source name. The result of \c get_default_source_name
      *     is used, if the parameter is not specified.
      * \li \c registration - Specifies the event source registration mode in the Windows registry.
      *     Can have values of the \c registration_mode enum. Default value: \c on_demand.
      *
      * \param args A set of named parameters.
      */
 #ifndef BOOST_LOG_DOXYGEN_PASS
     BOOST_LOG_PARAMETRIZED_CONSTRUCTORS_CALL(basic_event_log_backend, construct)
 #else
     template< typename... ArgsT >
     explicit basic_event_log_backend(ArgsT... const& args);
 #endif
 
     /*!
      * Destructor. Unregisters event source. The log source description is not removed from the Windows registry.
      */
     BOOST_LOG_API ~basic_event_log_backend();
 
     /*!
      * The method creates an event in the event log
      *
      * \param rec Log record to consume
      */
     BOOST_LOG_API void consume(record_view const& rec);
 
     /*!
      * The method installs the function object that maps application severity levels to WinAPI event types
      */
     BOOST_LOG_API void set_event_type_mapper(event_type_mapper_type const& mapper);
 
     /*!
      * The method installs the function object that extracts event category from attribute values
      */
     BOOST_LOG_API void set_event_category_mapper(event_category_mapper_type const& mapper);
 
     /*!
      * The method installs the function object that extracts event identifier from the attributes and creates
      * insertion strings that will replace placeholders in the event message.
      */
     BOOST_LOG_API void set_event_composer(event_composer_type const& composer);
 
     /*!
      * \returns Default log name: Application
      */
     BOOST_LOG_API static string_type get_default_log_name();
     /*!
      * \returns Default log source name that is based on the application executable file name and the sink name
      */
     BOOST_LOG_API static string_type get_default_source_name();
 
 private:
 #ifndef BOOST_LOG_DOXYGEN_PASS
     //! Constructs backend implementation
     template< typename ArgsT >
     void construct(ArgsT const& args)
     {
         construct(
             filesystem::path(args[keywords::message_file | filesystem::path()]),
             args[keywords::target | string_type()],
             args[keywords::log_name || &basic_event_log_backend::get_default_log_name],
             args[keywords::log_source || &basic_event_log_backend::get_default_source_name],
             args[keywords::registration | event_log::on_demand]);
     }
     BOOST_LOG_API void construct(
         filesystem::path const& message_file_name,
         string_type const& target,
         string_type const& log_name,
         string_type const& source_name,
         event_log::registration_mode reg_mode);
 #endif // BOOST_LOG_DOXYGEN_PASS
 };
 
 #ifdef BOOST_LOG_USE_CHAR
 typedef basic_simple_event_log_backend< char > simple_event_log_backend;      //!< Convenience typedef for narrow-character logging
 typedef basic_event_log_backend< char > event_log_backend;                    //!< Convenience typedef for narrow-character logging
 #endif
 #ifdef BOOST_LOG_USE_WCHAR_T
 typedef basic_simple_event_log_backend< wchar_t > wsimple_event_log_backend;  //!< Convenience typedef for wide-character logging
 typedef basic_event_log_backend< wchar_t > wevent_log_backend;                //!< Convenience typedef for wide-character logging
 #endif
 
 } // namespace sinks
 
 BOOST_LOG_CLOSE_NAMESPACE // namespace log
 
 } // namespace boost
 
 #include <boost/log/detail/footer.hpp>
 
 #endif // BOOST_LOG_WITHOUT_EVENT_LOG
 
 #endif // BOOST_LOG_SINKS_EVENT_LOG_BACKEND_HPP_INCLUDED_

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