/*

Copyright (c) 2008-2018, 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.

*/

#include "libtorrent/create_torrent.hpp"
#include "libtorrent/utf8.hpp"
#include "libtorrent/disk_io_thread.hpp"
#include "libtorrent/aux_/merkle.hpp" // for merkle_*()
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/announce_entry.hpp"
#include "libtorrent/performance_counters.hpp" // for counters
#include "libtorrent/alert_manager.hpp"
#include "libtorrent/aux_/path.hpp"

#include <sys/types.h>
#include <sys/stat.h>

#include <functional>
#include <memory>

using namespace std::placeholders;

namespace libtorrent {

	constexpr create_flags_t create_torrent::optimize_alignment;
#if TORRENT_ABI_VERSION == 1
	constexpr create_flags_t create_torrent::optimize;
#endif
	constexpr create_flags_t create_torrent::merkle;
	constexpr create_flags_t create_torrent::modification_time;
	constexpr create_flags_t create_torrent::symlinks;
	constexpr create_flags_t create_torrent::mutable_torrent_support;

namespace {

	bool default_pred(std::string const&) { return true; }

	bool ignore_subdir(std::string const& leaf)
	{ return leaf == ".." || leaf == "."; }

#ifndef TORRENT_WINDOWS
	std::string get_symlink_path_impl(char const* path)
	{
		constexpr int MAX_SYMLINK_PATH = 200;

		char buf[MAX_SYMLINK_PATH];
		std::string f = convert_to_native_path_string(path);
		int char_read = int(readlink(f.c_str(), buf, MAX_SYMLINK_PATH));
		if (char_read < 0) return "";
		if (char_read < MAX_SYMLINK_PATH) buf[char_read] = 0;
		else buf[0] = 0;
		return convert_from_native_path(buf);
	}
#endif

	void add_files_impl(file_storage& fs, std::string const& p
		, std::string const& l, std::function<bool(std::string)> const& pred
		, create_flags_t const flags)
	{
		std::string const f = combine_path(p, l);
		if (!pred(f)) return;
		error_code ec;
		file_status s;
		stat_file(f, &s, ec, (flags & create_torrent::symlinks) ? dont_follow_links : 0);
		if (ec) return;

		// recurse into directories
		bool recurse = (s.mode & file_status::directory) != 0;

		// if the file is not a link or we're following links, and it's a directory
		// only then should we recurse
#ifndef TORRENT_WINDOWS
		if ((s.mode & file_status::link) && (flags & create_torrent::symlinks))
			recurse = false;
#endif

		if (recurse)
		{
			for (directory i(f, ec); !i.done(); i.next(ec))
			{
				std::string const leaf = i.file();
				if (ignore_subdir(leaf)) continue;
				add_files_impl(fs, p, combine_path(l, leaf), pred, flags);
			}
		}
		else
		{
			// #error use the fields from s
			file_flags_t const file_flags = aux::get_file_attributes(f);

			// mask all bits to check if the file is a symlink
			if ((file_flags & file_storage::flag_symlink)
				&& (flags & create_torrent::symlinks))
			{
				std::string const sym_path = aux::get_symlink_path(f);
				fs.add_file(l, 0, file_flags, std::time_t(s.mtime), sym_path);
			}
			else
			{
				fs.add_file(l, s.file_size, file_flags, std::time_t(s.mtime));
			}
		}
	}

	struct hash_state
	{
		create_torrent& ct;
		storage_holder storage;
		disk_io_thread& iothread;
		piece_index_t piece_counter;
		piece_index_t completed_piece;
		std::function<void(piece_index_t)> const& f;
		error_code& ec;
	};

	void on_hash(piece_index_t const piece, sha1_hash const& piece_hash
		, storage_error const& error, hash_state* st)
	{
		if (error)
		{
			// on error
			st->ec = error.ec;
			st->iothread.abort(true);
			return;
		}
		st->ct.set_hash(piece, piece_hash);
		st->f(st->completed_piece);
		++st->completed_piece;
		if (st->piece_counter < st->ct.files().end_piece())
		{
			st->iothread.async_hash(st->storage, st->piece_counter
				, disk_interface::sequential_access
				, std::bind(&on_hash, _1, _2, _3, st));
			++st->piece_counter;
		}
		else
		{
			st->iothread.abort(true);
		}
		st->iothread.submit_jobs();
	}

} // anonymous namespace

namespace aux {

	file_flags_t get_file_attributes(std::string const& p)
	{
		auto const path = convert_to_native_path_string(p);

#ifdef TORRENT_WINDOWS
		WIN32_FILE_ATTRIBUTE_DATA attr;
		GetFileAttributesExW(path.c_str(), GetFileExInfoStandard, &attr);
		if (attr.dwFileAttributes == INVALID_FILE_ATTRIBUTES) return {};
		if (attr.dwFileAttributes & FILE_ATTRIBUTE_HIDDEN) return file_storage::flag_hidden;
		return {};
#else
		struct ::stat s{};
		if (::lstat(path.c_str(), &s) < 0) return {};
		file_flags_t file_attr = {};
		if (s.st_mode & S_IXUSR)
			file_attr |= file_storage::flag_executable;
		if (S_ISLNK(s.st_mode))
			file_attr |= file_storage::flag_symlink;
		return file_attr;
#endif
	}

	std::string get_symlink_path(std::string const& p)
	{
#if defined TORRENT_WINDOWS
		TORRENT_UNUSED(p);
		return "";
#else
		return get_symlink_path_impl(p.c_str());
#endif
	}

} // anonymous aux

#if TORRENT_ABI_VERSION == 1

	void add_files(file_storage& fs, std::wstring const& wfile
		, std::function<bool(std::string)> p, create_flags_t const flags)
	{
		std::string utf8 = wchar_utf8(wfile);
		add_files_impl(fs, parent_path(complete(utf8))
			, filename(utf8), p, flags);
	}

	void add_files(file_storage& fs
		, std::wstring const& wfile, create_flags_t const flags)
	{
		std::string utf8 = wchar_utf8(wfile);
		add_files_impl(fs, parent_path(complete(utf8))
			, filename(utf8), default_pred, flags);
	}

	void set_piece_hashes(create_torrent& t, std::wstring const& p
		, std::function<void(int)> f, error_code& ec)
	{
		std::string utf8 = wchar_utf8(p);
		set_piece_hashes(t, utf8, f, ec);
	}

	void set_piece_hashes_deprecated(create_torrent& t, std::wstring const& p
		, std::function<void(int)> f, error_code& ec)
	{
		std::string utf8 = wchar_utf8(p);
		set_piece_hashes(t, utf8, f, ec);
	}
#endif // TORRENT_ABI_VERSION

	void add_files(file_storage& fs, std::string const& file
		, std::function<bool(std::string)> p, create_flags_t const flags)
	{
		add_files_impl(fs, parent_path(complete(file)), filename(file), p, flags);
	}

	void add_files(file_storage& fs, std::string const& file, create_flags_t const flags)
	{
		add_files_impl(fs, parent_path(complete(file)), filename(file)
			, default_pred, flags);
	}

namespace {
	struct disk_aborter
	{
		explicit disk_aborter(disk_io_thread& dio) : m_dio(dio) {}
		~disk_aborter() { m_dio.abort(true); }
		disk_aborter(disk_aborter const&) = delete;
		disk_aborter& operator=(disk_aborter const&) = delete;
	private:
		disk_io_thread& m_dio;
	};
}

	void set_piece_hashes(create_torrent& t, std::string const& p
		, std::function<void(piece_index_t)> const& f, error_code& ec)
	{
		// optimized path
#ifdef TORRENT_BUILD_SIMULATOR
		sim::default_config conf;
		sim::simulation sim{conf};
		io_service ios{sim};
#else
		io_service ios;
#endif

#if TORRENT_USE_UNC_PATHS
		std::string const path = canonicalize_path(p);
#else
		std::string const& path = p;
#endif

		if (t.files().num_files() == 0)
		{
			ec = errors::no_files_in_torrent;
			return;
		}

		if (t.files().total_size() == 0)
		{
			ec = errors::torrent_invalid_length;
			return;
		}

		counters cnt;
		aux::session_settings sett;

		sett.set_int(settings_pack::cache_size, 0);
		int const num_threads = disk_io_thread::hasher_thread_divisor - 1;
		int const jobs_per_thread = 4;
		sett.set_int(settings_pack::aio_threads, num_threads);

		disk_io_thread disk_thread(ios, sett, cnt);
		disk_aborter da(disk_thread);

		aux::vector<download_priority_t, file_index_t> priorities;
		sha1_hash info_hash;
		storage_params params{
			t.files(),
			nullptr,
			path,
			storage_mode_t::storage_mode_sparse,
			priorities,
			info_hash
		};

		storage_holder storage = disk_thread.new_torrent(default_storage_constructor
			, params, std::shared_ptr<void>());

		int const piece_read_ahead = std::max(num_threads * jobs_per_thread
			, default_block_size / t.piece_length());

		hash_state st = { t, std::move(storage), disk_thread, piece_index_t(0), piece_index_t(0), f, ec };
		for (piece_index_t i(0); i < piece_index_t(piece_read_ahead); ++i)
		{
			disk_thread.async_hash(st.storage, i, disk_interface::sequential_access
				, std::bind(&on_hash, _1, _2, _3, &st));
			++st.piece_counter;
			if (st.piece_counter >= t.files().end_piece()) break;
		}
		disk_thread.submit_jobs();

#ifdef TORRENT_BUILD_SIMULATOR
		sim.run();
#else
		ios.run(ec);
#endif
	}

	create_torrent::~create_torrent() = default;

	create_torrent::create_torrent(file_storage& fs, int piece_size
		, int pad_file_limit, create_flags_t const flags, int alignment)
		: m_files(fs)
		, m_creation_date(::time(nullptr))
		, m_multifile(fs.num_files() > 1)
		, m_private(false)
		, m_merkle_torrent(bool(flags & create_torrent::merkle))
		, m_include_mtime(bool(flags & create_torrent::modification_time))
		, m_include_symlinks(bool(flags & create_torrent::symlinks))
	{
		// return instead of crash in release mode
		if (fs.num_files() == 0 || fs.total_size() == 0) return;

		if (!m_multifile && has_parent_path(m_files.file_path(file_index_t(0))))
			m_multifile = true;

		// a piece_size of 0 means automatic
		if (piece_size == 0 && !m_merkle_torrent)
		{
			// size_table is computed from the following:
			//   target_list_size = sqrt(total_size) * 2;
			//   target_piece_size = total_size / (target_list_size / hash_size);
			// Given hash_size = 20 bytes, target_piece_size = (16*1024 * pow(2, i))
			// we can determine size_table = (total_size = pow(2 * target_piece_size / hash_size, 2))
			std::array<std::int64_t, 10> const size_table{{
				       2684355LL // ->  16kiB
				,     10737418LL // ->  32 kiB
				,     42949673LL // ->  64 kiB
				,    171798692LL // -> 128 kiB
				,    687194767LL // -> 256 kiB
				,   2748779069LL // -> 512 kiB
				,  10995116278LL // -> 1 MiB
				,  43980465111LL // -> 2 MiB
				, 175921860444LL // -> 4 MiB
				, 703687441777LL}}; // -> 8 MiB

			int i = 0;
			for (auto const s : size_table)
			{
				if (s >= fs.total_size()) break;
				++i;
			}
			piece_size = default_block_size << i;
		}
		else if (piece_size == 0 && m_merkle_torrent)
		{
			piece_size = 64*1024;
		}

		// to support mutable torrents, alignment always has to be the piece size,
		// because piece hashes are compared to determine whether files are
		// identical
		if (flags & mutable_torrent_support)
			alignment = piece_size;

		// make sure the size is an even power of 2
		// i.e. only a single bit is set
		TORRENT_ASSERT((piece_size & (piece_size - 1)) == 0);

		m_files.set_piece_length(piece_size);
		if (flags & (optimize_alignment | mutable_torrent_support))
			m_files.optimize(pad_file_limit, alignment, bool(flags & mutable_torrent_support));

		m_files.set_num_pieces(static_cast<int>(
			(m_files.total_size() + m_files.piece_length() - 1) / m_files.piece_length()));
		m_piece_hash.resize(m_files.num_pieces());
	}

	create_torrent::create_torrent(torrent_info const& ti)
		: m_files(const_cast<file_storage&>(ti.files()))
		, m_creation_date(::time(nullptr))
		, m_multifile(ti.num_files() > 1)
		, m_private(ti.priv())
		, m_merkle_torrent(ti.is_merkle_torrent())
		, m_include_mtime(false)
		, m_include_symlinks(false)
	{
		TORRENT_ASSERT(ti.is_valid());
		TORRENT_ASSERT(ti.num_pieces() > 0);
		TORRENT_ASSERT(ti.num_files() > 0);
		TORRENT_ASSERT(ti.total_size() > 0);

		if (!ti.is_valid()) return;
		if (ti.creation_date() > 0) m_creation_date = ti.creation_date();

		if (!ti.creator().empty()) set_creator(ti.creator().c_str());
		if (!ti.comment().empty()) set_comment(ti.comment().c_str());

		for (auto const& n : ti.nodes())
			add_node(n);

		for (auto const& t : ti.trackers())
			add_tracker(t.url, t.tier);

		for (auto const& s : ti.web_seeds())
		{
			if (s.type == web_seed_entry::url_seed)
				add_url_seed(s.url);
			else if (s.type == web_seed_entry::http_seed)
				add_http_seed(s.url);
		}

		m_piece_hash.resize(m_files.num_pieces());
		for (auto const i : m_files.piece_range())
			set_hash(i, ti.hash_for_piece(i));

		boost::shared_array<char> const info = ti.metadata();
		int const size = ti.metadata_size();
		m_info_dict.preformatted().assign(&info[0], &info[0] + size);
	}

	entry create_torrent::generate() const
	{
		entry dict;

		if (m_files.num_files() == 0 || m_files.total_size() == 0)
			return dict;

		TORRENT_ASSERT(m_files.piece_length() > 0);

		if (!m_urls.empty()) dict["announce"] = m_urls.front().first;

		if (!m_nodes.empty())
		{
			entry& nodes = dict["nodes"];
			entry::list_type& nodes_list = nodes.list();
			for (auto const& n : m_nodes)
			{
				entry::list_type node;
				node.emplace_back(n.first);
				node.emplace_back(n.second);
				nodes_list.emplace_back(node);
			}
		}

		if (m_urls.size() > 1)
		{
			entry trackers(entry::list_t);
			entry tier(entry::list_t);
			int current_tier = m_urls.front().second;
			for (auto const& url : m_urls)
			{
				if (url.second != current_tier)
				{
					current_tier = url.second;
					trackers.list().push_back(tier);
					tier.list().clear();
				}
				tier.list().emplace_back(url.first);
			}
			trackers.list().push_back(tier);
			dict["announce-list"] = trackers;
		}

		if (!m_comment.empty())
			dict["comment"] = m_comment;

		dict["creation date"] = m_creation_date;

		if (!m_created_by.empty())
			dict["created by"] = m_created_by;

		if (!m_url_seeds.empty())
		{
			if (m_url_seeds.size() == 1)
			{
				dict["url-list"] = m_url_seeds.front();
			}
			else
			{
				entry& list = dict["url-list"];
				for (auto const& url : m_url_seeds)
				{
					list.list().emplace_back(url);
				}
			}
		}

		if (!m_http_seeds.empty())
		{
			if (m_http_seeds.size() == 1)
			{
				dict["httpseeds"] = m_http_seeds.front();
			}
			else
			{
				entry& list = dict["httpseeds"];
				for (auto const& url : m_http_seeds)
				{
					list.list().emplace_back(url);
				}
			}
		}

		entry& info = dict["info"];
		if (m_info_dict.type() == entry::dictionary_t
			|| m_info_dict.type() == entry::preformatted_t)
		{
			info = m_info_dict;
			return dict;
		}

		if (!m_collections.empty())
		{
			entry& list = info["collections"];
			for (auto const& c : m_collections)
			{
				list.list().emplace_back(c);
			}
		}

		if (!m_similar.empty())
		{
			entry& list = info["similar"];
			for (auto const& ih : m_similar)
			{
				list.list().emplace_back(ih.to_string());
			}
		}

		info["name"] = m_files.name();

		if (!m_root_cert.empty())
			info["ssl-cert"] = m_root_cert;

		if (m_private) info["private"] = 1;

		if (!m_multifile)
		{
			file_index_t const first(0);
			if (m_include_mtime) info["mtime"] = m_files.mtime(first);
			info["length"] = m_files.file_size(first);
			file_flags_t const flags = m_files.file_flags(first);
			if (flags & (file_storage::flag_pad_file
				| file_storage::flag_hidden
				| file_storage::flag_executable
				| file_storage::flag_symlink))
			{
				std::string& attr = info["attr"].string();
				if (flags & file_storage::flag_pad_file) attr += 'p';
				if (flags & file_storage::flag_hidden) attr += 'h';
				if (flags & file_storage::flag_executable) attr += 'x';
				if (m_include_symlinks && (flags & file_storage::flag_symlink)) attr += 'l';
			}
			if (m_include_symlinks
				&& (flags & file_storage::flag_symlink))
			{
				entry& sympath_e = info["symlink path"];

				for (auto elems = lsplit_path(m_files.symlink(first)); !elems.first.empty();
					elems = lsplit_path(elems.second))
					sympath_e.list().emplace_back(elems.first);
			}
			if (!m_filehashes.empty())
			{
				info["sha1"] = m_filehashes[first].to_string();
			}
		}
		else
		{
			if (!info.find_key("files"))
			{
				entry& files = info["files"];

				for (auto const i : m_files.file_range())
				{
					files.list().emplace_back();
					entry& file_e = files.list().back();
					if (m_include_mtime && m_files.mtime(i)) file_e["mtime"] = m_files.mtime(i);
					file_e["length"] = m_files.file_size(i);

					TORRENT_ASSERT(has_parent_path(m_files.file_path(i)));

					{
						entry& path_e = file_e["path"];

						std::string const p = m_files.file_path(i);
						// deliberately skip the first path element, since that's the
						// "name" of the torrent already
						string_view path = lsplit_path(p).second;
						for (auto elems = lsplit_path(path); !elems.first.empty(); elems = lsplit_path(elems.second))
							path_e.list().emplace_back(elems.first);
					}

					file_flags_t const flags = m_files.file_flags(i);
					if (flags)
					{
						std::string& attr = file_e["attr"].string();
						if (flags & file_storage::flag_pad_file) attr += 'p';
						if (flags & file_storage::flag_hidden) attr += 'h';
						if (flags & file_storage::flag_executable) attr += 'x';
						if (m_include_symlinks && (flags & file_storage::flag_symlink)) attr += 'l';
					}

					if (m_include_symlinks
						&& (flags & file_storage::flag_symlink))
					{
						entry& sympath_e = file_e["symlink path"];

						for (auto elems = lsplit_path(m_files.symlink(i)); !elems.first.empty();
							elems = lsplit_path(elems.second))
							sympath_e.list().emplace_back(elems.first);
					}
					if (!m_filehashes.empty() && m_filehashes[i] != sha1_hash())
					{
						file_e["sha1"] = m_filehashes[i].to_string();
					}
				}
			}
		}

		info["piece length"] = m_files.piece_length();
		if (m_merkle_torrent)
		{
			int const num_leafs = merkle_num_leafs(m_files.num_pieces());
			int const num_nodes = merkle_num_nodes(num_leafs);
			int const first_leaf = num_nodes - num_leafs;
			m_merkle_tree.resize(num_nodes);
			auto const num_pieces = int(m_piece_hash.size());
			for (int i = 0; i < num_pieces; ++i)
				m_merkle_tree[first_leaf + i] = m_piece_hash[piece_index_t(i)];
			for (int i = num_pieces; i < num_leafs; ++i)
				m_merkle_tree[first_leaf + i].clear();

			// now that we have initialized all leaves, build
			// each level bottom-up
			int level_start = first_leaf;
			int level_size = num_leafs;
			while (level_start > 0)
			{
				int parent = merkle_get_parent(level_start);
				for (int i = level_start; i < level_start + level_size; i += 2, ++parent)
				{
					hasher h;
					h.update(m_merkle_tree[i]);
					h.update(m_merkle_tree[i + 1]);
					m_merkle_tree[parent] = h.final();
				}
				level_start = merkle_get_parent(level_start);
				level_size /= 2;
			}
			TORRENT_ASSERT(level_size == 1);
			info["root hash"] = m_merkle_tree[0];
		}
		else
		{
			std::string& p = info["pieces"].string();

			for (sha1_hash const& h : m_piece_hash)
				p.append(h.data(), h.size());
		}

		return dict;
	}

	void create_torrent::add_tracker(string_view url, int const tier)
	{
		using announce_entry = std::pair<std::string, int>;
		auto const i = std::find_if(m_urls.begin(), m_urls.end()
			, [&url](announce_entry const& ae) { return ae.first == url; });
		if (i != m_urls.end()) return;
		m_urls.emplace_back(url.to_string(), tier);

		std::sort(m_urls.begin(), m_urls.end()
			, [](announce_entry const& lhs, announce_entry const& rhs)
			{ return lhs.second < rhs.second; });
	}

	void create_torrent::set_root_cert(string_view cert)
	{
		m_root_cert.assign(cert.data(), cert.size());
	}

	void create_torrent::add_similar_torrent(sha1_hash ih)
	{
		m_similar.emplace_back(ih);
	}

	void create_torrent::add_collection(string_view c)
	{
		m_collections.emplace_back(c);
	}

	void create_torrent::set_hash(piece_index_t index, sha1_hash const& h)
	{
		TORRENT_ASSERT(index >= piece_index_t(0));
		TORRENT_ASSERT(index < m_piece_hash.end_index());
		m_piece_hash[index] = h;
	}

	void create_torrent::set_file_hash(file_index_t index, sha1_hash const& h)
	{
		TORRENT_ASSERT(index >= file_index_t(0));
		TORRENT_ASSERT(index < m_files.end_file());
		if (m_filehashes.empty()) m_filehashes.resize(m_files.num_files());
		m_filehashes[index] = h;
	}

	void create_torrent::add_node(std::pair<std::string, int> node)
	{
		m_nodes.emplace_back(std::move(node));
	}

	void create_torrent::add_url_seed(string_view url)
	{
		m_url_seeds.emplace_back(url);
	}

	void create_torrent::add_http_seed(string_view url)
	{
		m_http_seeds.emplace_back(url);
	}

	void create_torrent::set_comment(char const* str)
	{
		if (str == nullptr) m_comment.clear();
		else m_comment = str;
	}

	void create_torrent::set_creator(char const* str)
	{
		if (str == nullptr) m_created_by.clear();
		else m_created_by = str;
	}
}