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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   text_file_backend.hpp
  * \author Andrey Semashev
  * \date   09.06.2009
  *
  * The header contains implementation of a text file sink backend.
  */
 
 #ifndef BOOST_LOG_SINKS_TEXT_FILE_BACKEND_HPP_INCLUDED_
 #define BOOST_LOG_SINKS_TEXT_FILE_BACKEND_HPP_INCLUDED_
 
 #include <ios>
 #include <string>
 #include <ostream>
 #include <boost/limits.hpp>
 #include <boost/cstdint.hpp>
 #include <boost/optional/optional.hpp>
 #include <boost/smart_ptr/shared_ptr.hpp>
 #include <boost/date_time/date_defs.hpp>
 #include <boost/date_time/special_defs.hpp>
 #include <boost/date_time/gregorian/greg_day.hpp>
 #include <boost/date_time/posix_time/posix_time_types.hpp>
 #include <boost/filesystem/path.hpp>
 #include <boost/log/keywords/max_size.hpp>
 #include <boost/log/keywords/max_files.hpp>
 #include <boost/log/keywords/min_free_space.hpp>
 #include <boost/log/keywords/target.hpp>
 #include <boost/log/keywords/target_file_name.hpp>
 #include <boost/log/keywords/file_name.hpp>
 #include <boost/log/keywords/open_mode.hpp>
 #include <boost/log/keywords/auto_flush.hpp>
 #include <boost/log/keywords/rotation_size.hpp>
 #include <boost/log/keywords/time_based_rotation.hpp>
 #include <boost/log/keywords/enable_final_rotation.hpp>
 #include <boost/log/keywords/auto_newline_mode.hpp>
 #include <boost/log/detail/config.hpp>
 #include <boost/log/detail/light_function.hpp>
 #include <boost/log/detail/parameter_tools.hpp>
 #include <boost/log/sinks/auto_newline_mode.hpp>
 #include <boost/log/sinks/basic_sink_backend.hpp>
 #include <boost/log/sinks/frontend_requirements.hpp>
 #include <boost/log/detail/header.hpp>
 
 #ifdef BOOST_HAS_PRAGMA_ONCE
 #pragma once
 #endif
 
 namespace boost {
 
 BOOST_LOG_OPEN_NAMESPACE
 
 namespace sinks {
 
 namespace file {
 
 //! The enumeration of the stored files scan methods
 enum scan_method
 {
     no_scan,        //!< Don't scan for stored files
     scan_matching,  //!< Scan for files with names matching the specified mask
     scan_all        //!< Scan for all files in the directory
 };
 
 //! The structure contains filesystem scanning results
 struct scan_result
 {
     //! The number of found files
     uintmax_t found_count;
     //! If populated, the largest file counter that was used in the found file names
     boost::optional< unsigned int > last_file_counter;
 
     scan_result() BOOST_NOEXCEPT :
         found_count(0u)
     {
     }
 };
 
 /*!
  * \brief Base class for file collectors
  *
  * All file collectors, supported by file sink backends, should inherit this class.
  */
 struct BOOST_LOG_NO_VTABLE collector
 {
     /*!
      * Default constructor
      */
     BOOST_DEFAULTED_FUNCTION(collector(), {})
 
     /*!
      * Virtual destructor
      */
 #if !defined(BOOST_LOG_NO_CXX11_DEFAULTED_VIRTUAL_FUNCTIONS)
     BOOST_DEFAULTED_FUNCTION(virtual ~collector(), {})
 #else
     virtual ~collector() {}
 #endif
 
     /*!
      * The function stores the specified file in the storage. May lead to an older file
      * deletion and a long file moving.
      *
      * \param src_path The name of the file to be stored
      */
     virtual void store_file(filesystem::path const& src_path) = 0;
 
     /*!
      * The function checks if the specified path refers to an existing file in the storage.
      *
      * \param src_path The path to be checked
      */
     virtual bool is_in_storage(filesystem::path const& src_path) const = 0;
 
     /*!
      * Scans the target directory for the files that have already been stored. The found
      * files are added to the collector in order to be tracked and erased, if needed.
      *
      * The function may scan the directory in two ways: it will either consider every
      * file in the directory a log file, or will only consider files with names that
      * match the specified pattern. The pattern may contain the following placeholders:
      *
      * \li %y, %Y, %m, %d - date components, in Boost.DateTime meaning.
      * \li %H, %M, %S, %f - time components, in Boost.DateTime meaning.
      * \li %N - numeric file counter. May also contain width specification
      *     in printf-compatible form (e.g. %5N). The resulting number will always be zero-filled.
      * \li %% - a percent sign
      *
      * All other placeholders are not supported.
      *
      * \param method The method of scanning. If \c no_scan is specified, the call has no effect.
      * \param pattern The file name pattern if \a method is \c scan_matching. Otherwise the parameter
      *                is not used.
      * \return The result of filesystem scanning. The last file counter is only populated if
      *         \a method is \c scan_matching, the \a pattern contains %N placeholder, and at least
      *         one file matching the pattern is found.
      *
      * \note In case if \a method is \c scan_matching the effect of this function is highly dependent
      *       on the \a pattern definition. It is recommended to choose patterns with easily
      *       distinguished placeholders (i.e. having delimiters between them). Otherwise
      *       either some files can be mistakenly found or not found, which in turn may lead
      *       to deletion of an unintended file.
      */
     virtual scan_result scan_for_files(scan_method method, filesystem::path const& pattern = filesystem::path()) = 0;
 
     BOOST_DELETED_FUNCTION(collector(collector const&))
     BOOST_DELETED_FUNCTION(collector& operator= (collector const&))
 };
 
 namespace aux {
 
     //! Creates and returns a file collector with the specified parameters
     BOOST_LOG_API shared_ptr< collector > make_collector(
         filesystem::path const& target_dir,
         uintmax_t max_size,
         uintmax_t min_free_space,
         uintmax_t max_files = (std::numeric_limits< uintmax_t >::max)()
     );
     template< typename ArgsT >
     inline shared_ptr< collector > make_collector(ArgsT const& args)
     {
         return aux::make_collector(
             filesystem::path(args[keywords::target]),
             args[keywords::max_size | (std::numeric_limits< uintmax_t >::max)()],
             args[keywords::min_free_space | static_cast< uintmax_t >(0)],
             args[keywords::max_files | (std::numeric_limits< uintmax_t >::max)()]);
     }
 
 } // namespace aux
 
 #ifndef BOOST_LOG_DOXYGEN_PASS
 
 template< typename T1 >
 inline shared_ptr< collector > make_collector(T1 const& a1)
 {
     return aux::make_collector(a1);
 }
 template< typename T1, typename T2 >
 inline shared_ptr< collector > make_collector(T1 const& a1, T2 const& a2)
 {
     return aux::make_collector((a1, a2));
 }
 template< typename T1, typename T2, typename T3 >
 inline shared_ptr< collector > make_collector(T1 const& a1, T2 const& a2, T3 const& a3)
 {
     return aux::make_collector((a1, a2, a3));
 }
 template< typename T1, typename T2, typename T3, typename T4 >
 inline shared_ptr< collector > make_collector(T1 const& a1, T2 const& a2, T3 const& a3, T4 const& a4)
 {
     return aux::make_collector((a1, a2, a3, a4));
 }
 
 #else
 
 /*!
  * The function creates a file collector for the specified target directory.
  * Each target directory is managed by a single file collector, so if
  * this function is called several times for the same directory,
  * it will return a reference to the same file collector. It is safe
  * to use the same collector in different sinks, even in a multithreaded
  * application.
  *
  * One can specify certain restrictions for the stored files, such as
  * maximum total size or minimum free space left in the target directory.
  * If any of the specified restrictions is not met, the oldest stored file
  * is deleted. If the same collector is requested more than once with
  * different restrictions, the collector will act according to the most strict
  * combination of all specified restrictions.
  *
  * The following named parameters are supported:
  *
  * \li \c target - Specifies the target directory for the files being stored in. This parameter
  *                 is mandatory.
  * \li \c max_size - Specifies the maximum total size, in bytes, of stored files that the collector
  *                   will try not to exceed. If the size exceeds this threshold the oldest file(s) is
  *                   deleted to free space. Note that the threshold may be exceeded if the size of
  *                   individual files exceed the \c max_size value. The threshold is not maintained,
  *                   if not specified.
  * \li \c min_free_space - Specifies the minimum free space, in bytes, in the target directory that
  *                         the collector tries to maintain. If the threshold is exceeded, the oldest
  *                         file(s) is deleted to free space. The threshold is not maintained, if not
  *                         specified.
  * \li \c max_files - Specifies the maximum number of log files stored.  If the number of files exceeds
  *                    this threshold, the oldest file(s) is deleted to free space.  The threshhold is
  *                    not maintained if not specified.
  *
  * \return The file collector.
  */
 template< typename... ArgsT >
 shared_ptr< collector > make_collector(ArgsT... const& args);
 
 #endif // BOOST_LOG_DOXYGEN_PASS
 
 /*!
  * The class represents the time point of log file rotation. One can specify one of three
  * types of time point based rotation:
  *
  * \li rotation takes place every day, at the specified time
  * \li rotation takes place on the specified day of every week, at the specified time
  * \li rotation takes place on the specified day of every month, at the specified time
  *
  * The time points are considered to be local time.
  */
 class rotation_at_time_point
 {
 public:
     typedef bool result_type;
 
 private:
     enum day_kind
     {
         not_specified,
         weekday,
         monthday
     };
 
     unsigned char m_Day : 6;
     unsigned char m_DayKind : 2; // contains day_kind values
     unsigned char m_Hour, m_Minute, m_Second;
 
     mutable posix_time::ptime m_Previous;
 
 public:
     /*!
      * Creates a rotation time point of every day at the specified time
      *
      * \param hour The rotation hour, should be within 0 and 23
      * \param minute The rotation minute, should be within 0 and 59
      * \param second The rotation second, should be within 0 and 59
      */
     BOOST_LOG_API explicit rotation_at_time_point(unsigned char hour, unsigned char minute, unsigned char second);
 
     /*!
      * Creates a rotation time point of each specified weekday at the specified time
      *
      * \param wday The weekday of the rotation
      * \param hour The rotation hour, should be within 0 and 23
      * \param minute The rotation minute, should be within 0 and 59
      * \param second The rotation second, should be within 0 and 59
      */
     BOOST_LOG_API explicit rotation_at_time_point(
         date_time::weekdays wday,
         unsigned char hour = 0,
         unsigned char minute = 0,
         unsigned char second = 0);
 
     /*!
      * Creates a rotation time point of each specified day of month at the specified time
      *
      * \param mday The monthday of the rotation, should be within 1 and 31
      * \param hour The rotation hour, should be within 0 and 23
      * \param minute The rotation minute, should be within 0 and 59
      * \param second The rotation second, should be within 0 and 59
      */
     BOOST_LOG_API explicit rotation_at_time_point(
         gregorian::greg_day mday,
         unsigned char hour = 0,
         unsigned char minute = 0,
         unsigned char second = 0);
 
     /*!
      * Checks if it's time to rotate the file
      */
     BOOST_LOG_API bool operator() () const;
 };
 
 /*!
  * The class represents the time interval of log file rotation. The log file will be rotated
  * after the specified time interval has passed.
  */
 class rotation_at_time_interval
 {
 public:
     typedef bool result_type;
 
 private:
     posix_time::time_duration m_Interval;
     mutable posix_time::ptime m_Previous;
 
 public:
     /*!
      * Creates a rotation time interval of the specified duration
      *
      * \param interval The interval of the rotation, should be no less than 1 second
      */
     explicit rotation_at_time_interval(posix_time::time_duration const& interval) :
         m_Interval(interval)
     {
         BOOST_ASSERT(!interval.is_special());
         BOOST_ASSERT(interval.total_seconds() > 0);
     }
 
     /*!
      * Checks if it's time to rotate the file
      */
     BOOST_LOG_API bool operator() () const;
 };
 
 } // namespace file
 
 
 /*!
  * \brief An implementation of a text file logging sink backend
  *
  * The sink backend puts formatted log records to a text file.
  * The sink supports file rotation and advanced file control, such as
  * size and file count restriction.
  */
 class text_file_backend :
     public basic_formatted_sink_backend<
         char,
         combine_requirements< synchronized_feeding, flushing >::type
     >
 {
     //! Base type
     typedef basic_formatted_sink_backend<
         char,
         combine_requirements< synchronized_feeding, flushing >::type
     > base_type;
 
 public:
     //! Character type
     typedef base_type::char_type char_type;
     //! String type to be used as a message text holder
     typedef base_type::string_type string_type;
     //! Stream type
     typedef std::basic_ostream< char_type > stream_type;
 
     //! File open handler
     typedef boost::log::aux::light_function< void (stream_type&) > open_handler_type;
     //! File close handler
     typedef boost::log::aux::light_function< void (stream_type&) > close_handler_type;
 
     //! Predicate that defines the time-based condition for file rotation
     typedef boost::log::aux::light_function< bool () > time_based_rotation_predicate;
 
 private:
     //! \cond
 
     struct implementation;
     implementation* m_pImpl;
 
     //! \endcond
 
 public:
     /*!
      * Default constructor. The constructed sink backend uses default values of all the parameters.
      */
     BOOST_LOG_API text_file_backend();
 
     /*!
      * Constructor. Creates a sink backend with the specified named parameters.
      * The following named parameters are supported:
      *
      * \li \c file_name - Specifies the active file name pattern where logs are actually written to. The pattern may
      *                    contain directory and file name portions, but only the file name may contain
      *                    placeholders. The backend supports Boost.DateTime placeholders for injecting
      *                    current time and date into the file name. Also, an additional %N placeholder is
      *                    supported, it will be replaced with an integral increasing file counter. The placeholder
      *                    may also contain width specification in the printf-compatible form (e.g. %5N). The
      *                    printed file counter will always be zero-filled. If \c file_name is not specified,
      *                    pattern "%5N.log" will be used.
      * \li \c target_file_name - Specifies the target file name pattern to use to rename the log file on rotation,
      *                           before passing it to the file collector. The pattern may contain the same
      *                           placeholders as the \c file_name parameter. By default, no renaming is done,
      *                           i.e. the written log file keeps its name according to \c file_name.
      * \li \c open_mode - File open mode. The mode should be presented in form of mask compatible to
      *                    <tt>std::ios_base::openmode</tt>. If not specified, <tt>trunc | out</tt> will be used.
      * \li \c rotation_size - Specifies the approximate size, in characters written, of the temporary file
      *                        upon which the file is passed to the file collector. Note the size does
      *                        not count any possible character conversions that may take place during
      *                        writing to the file. If not specified, the file won't be rotated upon reaching
      *                        any size.
      * \li \c time_based_rotation - Specifies the predicate for time-based file rotation.
      *                              No time-based file rotations will be performed, if not specified.
      * \li \c enable_final_rotation - Specifies a flag, whether or not perform log file rotation on
      *                                sink backend destruction. By default, is \c true.
      * \li \c auto_flush - Specifies a flag, whether or not to automatically flush the file after each
      *                     written log record. By default, is \c false.
      * \li \c auto_newline_mode - Specifies automatic trailing newline insertion mode. Must be a value of
      *                            the \c auto_newline_mode enum. By default, is <tt>auto_newline_mode::insert_if_missing</tt>.
      *
      * \note Read the caution note regarding file name pattern in the <tt>sinks::file::collector::scan_for_files</tt>
      *       documentation.
      */
 #ifndef BOOST_LOG_DOXYGEN_PASS
     BOOST_LOG_PARAMETRIZED_CONSTRUCTORS_CALL(text_file_backend, construct)
 #else
     template< typename... ArgsT >
     explicit text_file_backend(ArgsT... const& args);
 #endif
 
     /*!
      * Destructor
      */
     BOOST_LOG_API ~text_file_backend();
 
     /*!
      * The method sets the active file name wildcard for the files being written. The wildcard supports
      * date and time injection into the file name.
      *
      * \param pattern The name pattern for the file being written.
      */
     template< typename PathT >
     void set_file_name_pattern(PathT const& pattern)
     {
         set_file_name_pattern_internal(filesystem::path(pattern));
     }
 
     /*!
      * The method sets the target file name wildcard for the files being rotated. The wildcard supports
      * date and time injection into the file name.
      *
      * This pattern will be used when the log file is being rotated, to rename the just written
      * log file (which has the name according to the pattern in the \c file_name constructor parameter or
      * set by a call to \c set_file_name_pattern), just before passing the file to the file collector.
      *
      * \param pattern The name pattern for the file being rotated.
      */
     template< typename PathT >
     void set_target_file_name_pattern(PathT const& pattern)
     {
         set_target_file_name_pattern_internal(filesystem::path(pattern));
     }
 
     /*!
      * The method sets the file open mode
      *
      * \param mode File open mode
      */
     BOOST_LOG_API void set_open_mode(std::ios_base::openmode mode);
 
     /*!
      * The method sets the log file collector function. The function is called
      * on file rotation and is being passed the written file name.
      *
      * \param collector The file collector function object
      */
     BOOST_LOG_API void set_file_collector(shared_ptr< file::collector > const& collector);
 
     /*!
      * The method sets file opening handler. The handler will be called every time
      * the backend opens a new temporary file. The handler may write a header to the
      * opened file in order to maintain file validity.
      *
      * \param handler The file open handler function object
      */
     BOOST_LOG_API void set_open_handler(open_handler_type const& handler);
 
     /*!
      * The method sets file closing handler. The handler will be called every time
      * the backend closes a temporary file. The handler may write a footer to the
      * opened file in order to maintain file validity.
      *
      * \param handler The file close handler function object
      */
     BOOST_LOG_API void set_close_handler(close_handler_type const& handler);
 
     /*!
      * The method sets maximum file size. When the size is reached, file rotation is performed.
      *
      * \note The size does not count any possible character translations that may happen in
      *       the underlying API. This may result in greater actual sizes of the written files.
      *
      * \param size The maximum file size, in characters.
      */
     BOOST_LOG_API void set_rotation_size(uintmax_t size);
 
     /*!
      * The method sets the predicate that defines the time-based condition for file rotation.
      *
      * \note The rotation always occurs on writing a log record, so the rotation is
      *       not strictly bound to the specified condition.
      *
      * \param predicate The predicate that defines the time-based condition for file rotation.
      *                  If empty, no time-based rotation will take place.
      */
     BOOST_LOG_API void set_time_based_rotation(time_based_rotation_predicate const& predicate);
 
     /*!
      * The method allows to enable or disable log file rotation on sink destruction.
      *
      * By default the sink backend will rotate the log file, if it's been written to, on
      * destruction.
      *
      * \param enable The flag indicates whether the final rotation should be performed.
      */
     BOOST_LOG_API void enable_final_rotation(bool enable);
 
     /*!
      * Sets the flag to automatically flush write buffers of the file being written after each log record.
      *
      * \param enable The flag indicates whether the automatic buffer flush should be performed.
      */
     BOOST_LOG_API void auto_flush(bool enable = true);
 
     /*!
      * Selects whether a trailing newline should be automatically inserted after every log record. See
      * \c auto_newline_mode description for the possible modes of operation.
      *
      * \param mode The trailing newline insertion mode.
      */
     BOOST_LOG_API void set_auto_newline_mode(auto_newline_mode mode);
 
     /*!
      * \return The name of the currently open log file. If no file is open, returns an empty path.
      */
     BOOST_LOG_API filesystem::path get_current_file_name() const;
 
     /*!
      * Performs scanning of the target directory for log files that may have been left from
      * previous runs of the application. The found files are considered by the file collector
      * as if they were rotated.
      *
      * The file scan can be performed in two ways: either all files in the target directory will
      * be considered as log files, or only those files that satisfy the target file name pattern.
      * See documentation on <tt>sinks::file::collector::scan_for_files</tt> for more information.
      *
      * \pre File collector and the proper file name pattern have already been set.
      *
      * \param method File scanning method
      * \param update_counter If \c true and \a method is \c scan_matching, the method attempts
      *        to update the internal file counter according to the found files. The counter
      *        is unaffected otherwise.
      * \return The number of files found.
      *
      * \note The method essentially delegates to the same-named function of the file collector.
      */
     BOOST_LOG_API uintmax_t scan_for_files(
         file::scan_method method = file::scan_matching, bool update_counter = true);
 
     /*!
      * The method writes the message to the sink
      */
     BOOST_LOG_API void consume(record_view const& rec, string_type const& formatted_message);
 
     /*!
      * The method flushes the currently open log file
      */
     BOOST_LOG_API void flush();
 
     /*!
      * The method rotates the file
      */
     BOOST_LOG_API void rotate_file();
 
 private:
 #ifndef BOOST_LOG_DOXYGEN_PASS
     //! Constructor implementation
     template< typename ArgsT >
     void construct(ArgsT const& args)
     {
         construct(
             filesystem::path(args[keywords::file_name | filesystem::path()]),
             filesystem::path(args[keywords::target_file_name | filesystem::path()]),
             args[keywords::open_mode | (std::ios_base::trunc | std::ios_base::out)],
             args[keywords::rotation_size | (std::numeric_limits< uintmax_t >::max)()],
             args[keywords::time_based_rotation | time_based_rotation_predicate()],
             args[keywords::auto_newline_mode | insert_if_missing],
             args[keywords::auto_flush | false],
             args[keywords::enable_final_rotation | true]);
     }
     //! Constructor implementation
     BOOST_LOG_API void construct(
         filesystem::path const& pattern,
         filesystem::path const& target_file_name,
         std::ios_base::openmode mode,
         uintmax_t rotation_size,
         time_based_rotation_predicate const& time_based_rotation,
         auto_newline_mode auto_newline,
         bool auto_flush,
         bool enable_final_rotation);
 
     //! The method sets file name pattern
     BOOST_LOG_API void set_file_name_pattern_internal(filesystem::path const& pattern);
     //! The method sets target file name pattern
     BOOST_LOG_API void set_target_file_name_pattern_internal(filesystem::path const& pattern);
 
     //! Closes the currently open file
     void close_file();
 #endif // BOOST_LOG_DOXYGEN_PASS
 };
 
 } // namespace sinks
 
 BOOST_LOG_CLOSE_NAMESPACE // namespace log
 
 } // namespace boost
 
 #include <boost/log/detail/footer.hpp>
 
 #endif // BOOST_LOG_SINKS_TEXT_FILE_BACKEND_HPP_INCLUDED_

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