/*

Copyright (c) 2003-2016, Arvid Norberg
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/

#ifndef TORRENT_FILE_HPP_INCLUDED
#define TORRENT_FILE_HPP_INCLUDED

#include <memory>
#include <string>
#include <functional>

#include "libtorrent/config.hpp"
#include "libtorrent/string_view.hpp"
#include "libtorrent/span.hpp"
#include "libtorrent/aux_/storage_utils.hpp"
#include "libtorrent/flags.hpp"

#include "libtorrent/aux_/disable_warnings_push.hpp"

#include <boost/noncopyable.hpp>

#ifdef TORRENT_WINDOWS
// windows part
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#include <winioctl.h>
#include <sys/types.h>
#else
// posix part
#define _FILE_OFFSET_BITS 64

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif

#ifndef _XOPEN_SOURCE
#define _XOPEN_SOURCE 600
#endif

#include <unistd.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <dirent.h> // for DIR

#include "libtorrent/aux_/max_path.hpp" // for TORRENT_MAX_PATH

#undef _FILE_OFFSET_BITS

#endif

#include "libtorrent/aux_/disable_warnings_pop.hpp"

#include "libtorrent/error_code.hpp"
#include "libtorrent/assert.hpp"
#include "libtorrent/time.hpp"

namespace libtorrent {

#ifdef TORRENT_WINDOWS
	using handle_type = HANDLE;
#else
	using handle_type = int;
#endif

	class TORRENT_EXTRA_EXPORT directory : public boost::noncopyable
	{
	public:
		directory(std::string const& path, error_code& ec);
		~directory();
		void next(error_code& ec);
		std::string file() const;
		std::uint64_t inode() const;
		bool done() const { return m_done; }
	private:
#ifdef TORRENT_WINDOWS
		HANDLE m_handle;
		int m_inode;
#if TORRENT_USE_WSTRING
		WIN32_FIND_DATAW m_fd;
#else
		WIN32_FIND_DATAA m_fd;
#endif
#else
		DIR* m_handle;
		// the dirent struct contains a zero-sized
		// array at the end, it will end up referring
		// to the m_name field
		struct dirent m_dirent;
		char m_name[TORRENT_MAX_PATH + 1]; // +1 to make room for terminating 0
#endif
		bool m_done;
	};

	struct file;

	using file_handle = std::shared_ptr<file>;

	// the open mode for files. Used for the file constructor or
	// file::open().
	enum class open_mode_t : std::uint32_t
	{
		none = 0,

		// open the file for reading only
		read_only = 0,

		// open the file for writing only
		write_only = 1,

		// open the file for reading and writing
		read_write = 2,

		// the mask for the bits determining read or write mode
		rw_mask = read_only | write_only | read_write,

		// open the file in sparse mode (if supported by the
		// filesystem).
		sparse = 0x4,

		// don't update the access timestamps on the file (if
		// supported by the operating system and filesystem).
		// this generally improves disk performance.
		no_atime = 0x8,

		// open the file for random access. This disables read-ahead
		// logic
		random_access = 0x10,

		// prevent the file from being opened by another process
		// while it's still being held open by this handle
		lock_file = 0x20,

		// don't put any pressure on the OS disk cache
		// because of access to this file. We expect our
		// files to be fairly large, and there is already
		// a cache at the bittorrent block level. This
		// may improve overall system performance by
		// leaving running applications in the page cache
		no_cache = 0x40,

		// this is only used for readv/writev flags
		coalesce_buffers = 0x100,

		// when creating a file, set the hidden attribute (windows only)
		attribute_hidden = 0x200,

		// when creating a file, set the executable attribute
		attribute_executable = 0x400,

		// the mask of all attribute bits
		attribute_mask = attribute_hidden | attribute_executable
	};

namespace flags {
	template <>
	struct enable_flag_operators<open_mode_t> : std::true_type {};
}

	using namespace flags;

	struct TORRENT_EXTRA_EXPORT file : boost::noncopyable
	{
		file();
		file(std::string const& p, open_mode_t m, error_code& ec);
		~file();

		bool open(std::string const& p, open_mode_t m, error_code& ec);
		bool is_open() const;
		void close();
		bool set_size(std::int64_t size, error_code& ec);

		open_mode_t open_mode() const { return m_open_mode; }

		std::int64_t writev(std::int64_t file_offset, span<iovec_t const> bufs
			, error_code& ec, open_mode_t flags = open_mode_t::none);
		std::int64_t readv(std::int64_t file_offset, span<iovec_t const> bufs
			, error_code& ec, open_mode_t flags = open_mode_t::none);

		std::int64_t get_size(error_code& ec) const;

		// return the offset of the first byte that
		// belongs to a data-region
		std::int64_t sparse_end(std::int64_t start) const;

		handle_type native_handle() const { return m_file_handle; }

	private:

		handle_type m_file_handle;

		open_mode_t m_open_mode = open_mode_t::none;
#if defined TORRENT_WINDOWS
		static bool has_manage_volume_privs;
#endif
	};
}

#endif // TORRENT_FILE_HPP_INCLUDED