/*

Copyright (c) 2003-2012, 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_STORAGE_HPP_INCLUDED
#define TORRENT_FILE_STORAGE_HPP_INCLUDED

#include <string>
#include <vector>
#include <ctime>

#include "libtorrent/size_type.hpp"
#include "libtorrent/assert.hpp"
#include "libtorrent/peer_request.hpp"
#include "libtorrent/peer_id.hpp"

namespace libtorrent
{
	struct file;

	// information about a file in a file_storage
	struct TORRENT_EXPORT file_entry
	{
		// hidden
		file_entry();
		// hidden
		~file_entry();

		// the full path of this file. The paths are unicode strings
		// encoded in UTF-8.
		std::string path;

		// the offset of this file inside the torrent
		size_type offset;

		// the size of the file (in bytes) and ``offset`` is the byte offset
		// of the file within the torrent. i.e. the sum of all the sizes of the files
		// before it in the list.
		size_type size;

		// the offset in the file where the storage should start. The normal
		// case is to have this set to 0, so that the storage starts saving data at the start
		// if the file. In cases where multiple files are mapped into the same file though,
		// the ``file_base`` should be set to an offset so that the different regions do
		// not overlap. This is used when mapping "unselected" files into a so-called part
		// file.
		size_type file_base;

		// the modification time of this file specified in posix time.
		std::time_t mtime;

		// a sha-1 hash of the content of the file, or zeroes, if no
		// file hash was present in the torrent file. It can be used to potentially
		// find alternative sources for the file.
		sha1_hash filehash;

		// set to true for files that are not part of the data of the torrent.
		// They are just there to make sure the next file is aligned to a particular byte offset
		// or piece boundry. These files should typically be hidden from an end user. They are
		// not written to disk.
		bool pad_file:1;

		// true if the file was marked as hidden (on windows).
		bool hidden_attribute:1;

		// true if the file was marked as executable (posix)
		bool executable_attribute:1;

		// true if the file was a symlink. If this is the case
		// the ``symlink_index`` refers to a string which specifies the original location
		// where the data for this file was found.
		bool symlink_attribute:1;

		// the path which this is a symlink to, or empty if this is
		// not a symlink. This field is only used if the ``symlink_attribute`` is set.
		std::string symlink_path;
	};

	// only export this type if deprecated functions are enabled
#ifdef TORRENT_NO_DEPRECATED
#define TORRENT_DEPRECATED_EXPORT
#else
#define TORRENT_DEPRECATED_EXPORT TORRENT_EXPORT
#endif
	// internal
	struct TORRENT_DEPRECATED_EXPORT internal_file_entry
	{
		friend class file_storage;
#ifdef TORRENT_DEBUG
		// for torrent_info::invariant_check
		friend class torrent_info;
#endif
		internal_file_entry()
			: name(0)
			, offset(0)
			, symlink_index(-1)
			, size(0)
			, name_len(0)
			, pad_file(false)
			, hidden_attribute(false)
			, executable_attribute(false)
			, symlink_attribute(false)
			, path_index(-1)
		{}

		internal_file_entry(file_entry const& e)
			: name(0)
			, offset(e.offset)
			, symlink_index(-1)
			, size(e.size)
			, name_len(0)
			, pad_file(e.pad_file)
			, hidden_attribute(e.hidden_attribute)
			, executable_attribute(e.executable_attribute)
			, symlink_attribute(e.symlink_attribute)
			, path_index(-1)
		{
			set_name(e.path.c_str());
		}

		internal_file_entry(internal_file_entry const& fe);
		internal_file_entry& operator=(internal_file_entry const& fe);

		~internal_file_entry();

		void set_name(char const* n, int borrow_chars = 0);
		std::string filename() const;

		// make it available for logging
#if !defined TORRENT_VERBOSE_LOGGING \
	&& !defined TORRENT_LOGGING \
	&& !defined TORRENT_ERROR_LOGGING
	private:
#endif
		// This string is not necessarily null terminated!
		// that's why it's private, to keep people away from it
		char const* name;
	public:

		// the offset of this file inside the torrent
		size_type offset:48;

		// index into file_storage::m_symlinks or -1
		// if this is not a symlink
		size_type symlink_index:16;

		// the size of this file
		size_type size:48;

		// the number of characters in the name. If this is
		// 0, name is null terminated and owned by this object
		// (i.e. it should be freed in the destructor). If
		// the len is > 0, the name pointer doesn not belong
		// to this object, and it's not null terminated
		size_type name_len:10;
		bool pad_file:1;
		bool hidden_attribute:1;
		bool executable_attribute:1;
		bool symlink_attribute:1;
		// the index into file_storage::m_paths. To get
		// the full path to this file, concatenate the path
		// from that array with the 'name' field in
		// this struct
		// if path_index == -2, it means the filename
		// in this field contains the full, absolute path
		// to the file
		// -1 means no path (i.e. single file torrent)
		int path_index;
	};

	// represents a window of a file in a torrent.
	//
	// The ``file_index`` refers to the index of the file (in the torrent_info).
	// To get the path and filename, use ``file_at()`` and give the ``file_index``
	// as argument. The ``offset`` is the byte offset in the file where the range
	// starts, and ``size`` is the number of bytes this range is. The size + offset
	// will never be greater than the file size.
	struct TORRENT_EXPORT file_slice
	{
		// the index of the file
		int file_index;

		// the offset from the start of the file, in bytes
		size_type offset;

		// the size of the window, in bytes
		size_type size;
	};

	// The ``file_storage`` class represents a file list and the piece
	// size. Everything necessary to interpret a regular bittorrent storage
	// file structure.
	class TORRENT_EXPORT file_storage
	{
	friend class torrent_info;
	public:
		// hidden
		file_storage();
		// hidden
		~file_storage() {}

		// returns true if the piece length has been initialized
		// on the file_storage. This is typically taken as a proxy
		// of whether the file_storage as a whole is initialized or
		// not.
		bool is_valid() const { return m_piece_length > 0; }

		// file attribute flags
		enum flags_t
		{
			// the file is a pad file. It's required to contain zeroes
			// at it will not be saved to disk. Its purpose is to make
			// the following file start on a piece boundary.
			pad_file = 1,

			// this file has the hidden attribute set. This is primarily
			// a windows attribute
			attribute_hidden = 2,

			// this file has the executable attribute set.
			attribute_executable = 4,

			// this file is a symbilic link. It should have a link
			// target string associated with it.
			attribute_symlink = 8
		};

		// allocates space for ``num_files`` in the internal file list. This can
		// be used to avoid reallocating the internal file list when the number
		// of files to be added is known up-front.
		void reserve(int num_files);

		// Adds a file to the file storage. The ``flags`` argument sets attributes on the file.
		// The file attributes is an extension and may not work in all bittorrent clients.
		//
		// For possible file attributes, see file_storage::flags_t.
		//
		// If more files than one are added, certain restrictions to their paths apply.
		// In a multi-file file storage (torrent), all files must share the same root directory.
		// 
		// That is, the first path element of all files must be the same.
		// This shared path element is also set to the name of the torrent. It
		// can be changed by calling ``set_name``.
		//
		// The built in functions to traverse a directory to add files will
		// make sure this requirement is fulfilled.
		void add_file(file_entry const& e, char const* filehash = 0);
		void add_file(std::string const& p, size_type size, int flags = 0
			, std::time_t mtime = 0, std::string const& s_p = "");

		// renames the file at ``index`` to ``new_filename``. Keep in mind
		// that filenames are expected to be UTF-8 encoded.
		void rename_file(int index, std::string const& new_filename);

		// this is a low-level function that sets the name of a file
		// by making it reference a buffer that is not owned by the file_storage.
		// it's an optimization used when loading .torrent files, to not
		// duplicate names in memory.
		void rename_file_borrow(int index, char const* new_filename, int len);

#if TORRENT_USE_WSTRING
		// all wstring APIs are deprecated since 0.16.11
		// instead, use the wchar -> utf8 conversion functions
		// and pass in utf8 strings
#ifndef TORRENT_NO_DEPRECATE
		TORRENT_DEPRECATED_PREFIX
		void add_file(std::wstring const& p, size_type size, int flags = 0
			, std::time_t mtime = 0, std::string const& s_p = "") TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		void rename_file(int index, std::wstring const& new_filename) TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		void set_name(std::wstring const& n) TORRENT_DEPRECATED;
#endif // TORRENT_NO_DEPRECATE
#endif // TORRENT_USE_WSTRING

		// returns a list of file_slice objects representing the portions of
		// files the specified piece index, byte offset and size range overlaps.
		// this is the inverse mapping of map_file().
		std::vector<file_slice> map_block(int piece, size_type offset
			, int size) const;

		// returns a peer_request representing the piece index, byte offset
		// and size the specified file range overlaps. This is the inverse
		// mapping ove map_block().
		peer_request map_file(int file, size_type offset, int size) const;

#ifndef TORRENT_NO_DEPRECATE
		// all functions depending on internal_file_entry
		// were deprecated in 1.0. Use the variants that take an
		// index instead
		typedef std::vector<internal_file_entry>::const_iterator iterator;
		typedef std::vector<internal_file_entry>::const_reverse_iterator reverse_iterator;

		TORRENT_DEPRECATED_PREFIX
		iterator file_at_offset(size_type offset) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		iterator begin() const TORRENT_DEPRECATED { return m_files.begin(); }
		TORRENT_DEPRECATED_PREFIX
		iterator end() const TORRENT_DEPRECATED { return m_files.end(); }
		TORRENT_DEPRECATED_PREFIX
		reverse_iterator rbegin() const TORRENT_DEPRECATED { return m_files.rbegin(); }
		TORRENT_DEPRECATED_PREFIX
		reverse_iterator rend() const TORRENT_DEPRECATED { return m_files.rend(); }
		TORRENT_DEPRECATED_PREFIX
		internal_file_entry const& internal_at(int index) const TORRENT_DEPRECATED 
		{
			TORRENT_ASSERT(index >= 0);
			TORRENT_ASSERT(index < int(m_files.size()));
			return m_files[index];
		}
		TORRENT_DEPRECATED_PREFIX
		file_entry at(iterator i) const TORRENT_DEPRECATED;
#endif // TORRENT_NO_DEPRECATE

		// returns the number of files in the file_storage
		int num_files() const
		{ return int(m_files.size()); }

		// returns a file_entry with information about the file
		// at ``index``. Index must be in the range [0, ``num_files()`` ).
		file_entry at(int index) const;

		// returns the total number of bytes all the files in this torrent spans
		size_type total_size() const { return m_total_size; }

		// set and get the number of pieces in the torrent
		void set_num_pieces(int n) { m_num_pieces = n; }
		int num_pieces() const { TORRENT_ASSERT(m_piece_length > 0); return m_num_pieces; }

		// set and get the size of each piece in this torrent. This size is typically an even power
		// of 2. It doesn't have to be though. It should be divisible by 16kiB however.
		void set_piece_length(int l)  { m_piece_length = l; }
		int piece_length() const { TORRENT_ASSERT(m_piece_length > 0); return m_piece_length; }

		// returns the piece size of ``index``. This will be the same as piece_length(), except
		// for the last piece, which may be shorter.
		int piece_size(int index) const;

		// set and get the name of this torrent. For multi-file torrents, this is also
		// the name of the root directory all the files are stored in.
		void set_name(std::string const& n) { m_name = n; }
		const std::string& name() const { return m_name; }

		// swap all content of *this* with *ti*.
		void swap(file_storage& ti)
		{
			using std::swap;
			swap(ti.m_files, m_files);
			swap(ti.m_file_hashes, m_file_hashes);
			swap(ti.m_symlinks, m_symlinks);
			swap(ti.m_mtime, m_mtime);
			swap(ti.m_file_base, m_file_base);
			swap(ti.m_paths, m_paths);
			swap(ti.m_name, m_name);
			swap(ti.m_total_size, m_total_size);
			swap(ti.m_num_pieces, m_num_pieces);
			swap(ti.m_piece_length, m_piece_length);
		}

		// if pad_file_limit >= 0, files larger than
		// that limit will be padded, default is to
		// not add any padding
		void optimize(int pad_file_limit = -1, int alignment = 0x10000);

		// These functions are used to query attributes of files at
		// a given index.
		// 
		// The ``file_hash()`` is a sha-1 hash of the file, or 0 if none was
		// provided in the torrent file. This can potentially be used to
		// join a bittorrent network with other file sharing networks.
		// 
		// The ``mtime()`` is the modification time is the posix
		// time when a file was last modified when the torrent
		// was created, or 0 if it was not included in the torrent file.
		// 
		// ``file_path()`` returns the full path to a file.
		// 
		// ``file_size()`` returns the size of a file.
		// 
		// ``pad_file_at()`` returns true if the file at the given
		// index is a pad-file.
		//
		// ``file_name()`` returns *just* the name of the file, whereas
		// ``file_path()`` returns the path (inside the torrent file) with
		// the filename appended.
		//
		// ``file_offset()`` returns the byte offset within the torrent file
		// where this file starts. It can be used to map the file to a piece
		// index (given the piece size).
		sha1_hash hash(int index) const;
		std::string const& symlink(int index) const;
		time_t mtime(int index) const;
		std::string file_path(int index, std::string const& save_path = "") const;
		std::string file_name(int index) const;
		size_type file_size(int index) const;
		bool pad_file_at(int index) const;
		size_type file_offset(int index) const;

		enum file_flags_t
		{
			flag_pad_file = 1,
			flag_hidden = 2,
			flag_executable = 4,
			flag_symlink = 8,
		};

		// returns a bitmask of flags from file_flags_t that apply
		// to file at ``index``.
		int file_flags(int index) const;

		// The file base of a file is the offset within the file on the filsystem
		// where it starts to write. For the most part, this is always 0. It's
		// possible to map several files (in the torrent) into a single file on
		// the filesystem by making them all point to the same filename, but with
		// different file bases, so that they don't overlap.
		// torrent_info::remap_files() can be used to use a new file layout.
		size_type file_base(int index) const;
		void set_file_base(int index, size_type off);

		// returns the index of the file at the given offset in the torrent
		int file_index_at_offset(size_type offset) const;

		// low-level function. returns a pointer to the internal storage for
		// the filename. This string may not be null terinated!
		// the ``file_name_len()`` function returns the length of the filename.
		char const* file_name_ptr(int index) const;
		int file_name_len(int index) const;

#ifndef TORRENT_NO_DEPRECATE
		// these were deprecated in 1.0. Use the versions that take an index instead
		TORRENT_DEPRECATED_PREFIX
		sha1_hash hash(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		std::string const& symlink(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		time_t mtime(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		int file_index(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		size_type file_base(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		void set_file_base(internal_file_entry const& fe, size_type off) TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		std::string file_path(internal_file_entry const& fe, std::string const& save_path = "") const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		std::string file_name(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		size_type file_size(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		bool pad_file_at(internal_file_entry const& fe) const TORRENT_DEPRECATED;
		TORRENT_DEPRECATED_PREFIX
		size_type file_offset(internal_file_entry const& fe) const TORRENT_DEPRECATED;
#endif

#if !defined TORRENT_VERBOSE_LOGGING \
	&& !defined TORRENT_LOGGING \
	&& !defined TORRENT_ERROR_LOGGING
	private:
#endif

		void update_path_index(internal_file_entry& e);
		void reorder_file(int index, int dst);

		// the list of files that this torrent consists of
		std::vector<internal_file_entry> m_files;

		// if there are sha1 hashes for each individual file
		// there are as many entries in this array as the
		// m_files array. Each entry in m_files has a corresponding
		// hash pointer in this array. The reason to split it up
		// in separate arrays is to save memory in case the torrent
		// doesn't have file hashes
		std::vector<char const*> m_file_hashes;

		// for files that are symlinks, the symlink
		// path_index in the internal_file_entry indexes
		// this vector of strings
		std::vector<std::string> m_symlinks;

		// the modification times of each file. This vector
		// is empty if no file have a modification time.
		// each element corresponds to the file with the same
		// index in m_files
		std::vector<time_t> m_mtime;

		// if any file has a non-zero file base (i.e. multiple
		// files residing in the same physical file at different
		// offsets)
		std::vector<size_type> m_file_base;

		// all unique paths files have. The internal_file_entry::path_index
		// points into this array
		std::vector<std::string> m_paths;

		// name of torrent. For multi-file torrents
		// this is always the root directory
		std::string m_name;

		// the sum of all filesizes
		size_type m_total_size;

		// the number of pieces in the torrent
		int m_num_pieces;

		int m_piece_length;
	};
}

#endif // TORRENT_FILE_STORAGE_HPP_INCLUDED