/*

Copyright (c) 2015, 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 <cstdint>

#include "libtorrent/bdecode.hpp"
#include "libtorrent/read_resume_data.hpp"
#include "libtorrent/add_torrent_params.hpp"
#include "libtorrent/socket_io.hpp" // for read_*_endpoint()
#include "libtorrent/hasher.hpp"
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/aux_/numeric_cast.hpp"
#include "libtorrent/download_priority.hpp" // for default_priority

namespace libtorrent {

namespace {

	void apply_flag(torrent_flags_t& current_flags
		, bdecode_node const& n
		, char const* name
		, torrent_flags_t const flag)
	{
		if (n.dict_find_int_value(name, 0) == 0)
		{
			current_flags &= ~flag;
		}
		else
		{
			current_flags |= flag;
		}
	}

} // anonyous namespace

	add_torrent_params read_resume_data(bdecode_node const& rd, error_code& ec)
	{
		add_torrent_params ret;
		if (rd.type() != bdecode_node::dict_t)
		{
			ec = errors::not_a_dictionary;
			return ret;
		}

		if (bdecode_node const alloc = rd.dict_find_string("allocation"))
		{
			ret.storage_mode = (alloc.string_value() == "allocate"
				|| alloc.string_value() == "full")
				? storage_mode_allocate : storage_mode_sparse;
		}

		if (rd.dict_find_string_value("file-format")
			!= "libtorrent resume file")
		{
			ec = errors::invalid_file_tag;
			return ret;
		}

		auto info_hash = rd.dict_find_string_value("info-hash");
		if (info_hash.size() != sha1_hash::size())
		{
			ec = errors::missing_info_hash;
			return ret;
		}

		ret.name = rd.dict_find_string_value("name").to_string();

		ret.info_hash.assign(info_hash.data());

		bdecode_node const info = rd.dict_find_dict("info");
		if (info)
		{
			// verify the info-hash of the metadata stored in the resume file matches
			// the torrent we're loading
			sha1_hash const resume_ih = hasher(info.data_section()).final();

			// if url is set, the info_hash is not actually the info-hash of the
			// torrent, but the hash of the URL, until we have the full torrent
			// only require the info-hash to match if we actually passed in one
			if (resume_ih == ret.info_hash)
			{
				ret.ti = std::make_shared<torrent_info>(resume_ih);

				error_code err;
				if (!ret.ti->parse_info_section(info, err))
				{
					ec = err;
				}
			}
		}

		ret.total_uploaded = rd.dict_find_int_value("total_uploaded");
		ret.total_downloaded = rd.dict_find_int_value("total_downloaded");

		ret.active_time = int(rd.dict_find_int_value("active_time"));
		ret.finished_time = int(rd.dict_find_int_value("finished_time"));
		ret.seeding_time = int(rd.dict_find_int_value("seeding_time"));

		ret.last_seen_complete = std::time_t(rd.dict_find_int_value("last_seen_complete"));

		ret.last_download = std::time_t(rd.dict_find_int_value("last_download", 0));
		ret.last_upload = std::time_t(rd.dict_find_int_value("last_upload", 0));

		// scrape data cache
		ret.num_complete = int(rd.dict_find_int_value("num_complete", -1));
		ret.num_incomplete = int(rd.dict_find_int_value("num_incomplete", -1));
		ret.num_downloaded = int(rd.dict_find_int_value("num_downloaded", -1));

		// torrent settings
		ret.max_uploads = int(rd.dict_find_int_value("max_uploads", -1));
		ret.max_connections = int(rd.dict_find_int_value("max_connections", -1));
		ret.upload_limit = int(rd.dict_find_int_value("upload_rate_limit", -1));
		ret.download_limit = int(rd.dict_find_int_value("download_rate_limit", -1));

		// torrent state
		apply_flag(ret.flags, rd, "seed_mode", torrent_flags::seed_mode);
		apply_flag(ret.flags, rd, "super_seeding", torrent_flags::super_seeding);
		apply_flag(ret.flags, rd, "auto_managed", torrent_flags::auto_managed);
		apply_flag(ret.flags, rd, "sequential_download", torrent_flags::sequential_download);
		apply_flag(ret.flags, rd, "paused", torrent_flags::paused);

		ret.save_path = rd.dict_find_string_value("save_path").to_string();

#if TORRENT_ABI_VERSION == 1
		// deprecated in 1.2
		ret.url = rd.dict_find_string_value("url").to_string();
		ret.uuid = rd.dict_find_string_value("uuid").to_string();
#endif

		bdecode_node const mapped_files = rd.dict_find_list("mapped_files");
		if (mapped_files)
		{
			for (int i = 0; i < mapped_files.list_size(); ++i)
			{
				auto new_filename = mapped_files.list_string_value_at(i);
				if (new_filename.empty()) continue;
				ret.renamed_files[file_index_t(i)] = new_filename.to_string();
			}
		}

		ret.added_time = std::time_t(rd.dict_find_int_value("added_time", 0));
		ret.completed_time = std::time_t(rd.dict_find_int_value("completed_time", 0));

		// load file priorities except if the add_torrent_param file was set to
		// override resume data
		bdecode_node const file_priority = rd.dict_find_list("file_priority");
		if (file_priority)
		{
			int const num_files = file_priority.list_size();
			ret.file_priorities.resize(aux::numeric_cast<std::size_t>(num_files)
				, default_priority);
			for (int i = 0; i < num_files; ++i)
			{
				std::size_t const idx = std::size_t(i);
				ret.file_priorities[idx] = aux::clamp(
					download_priority_t(static_cast<std::uint8_t>(
						file_priority.list_int_value_at(i
							, static_cast<std::uint8_t>(default_priority))))
						, dont_download, top_priority);
				// this is suspicious, leave seed mode
				if (ret.file_priorities[idx] == dont_download)
				{
					ret.flags &= ~torrent_flags::seed_mode;
				}
			}
		}

		bdecode_node const trackers = rd.dict_find_list("trackers");
		if (trackers)
		{
			// it's possible to delete the trackers from a torrent and then save
			// resume data with an empty trackers list. Since we found a trackers
			// list here, these should replace whatever we find in the .torrent
			// file.
			ret.flags |= torrent_flags::override_trackers;

			int tier = 0;
			for (int i = 0; i < trackers.list_size(); ++i)
			{
				bdecode_node const tier_list = trackers.list_at(i);
				if (!tier_list || tier_list.type() != bdecode_node::list_t)
					continue;

				for (int j = 0; j < tier_list.list_size(); ++j)
				{
					ret.trackers.push_back(tier_list.list_string_value_at(j).to_string());
					ret.tracker_tiers.push_back(tier);
				}
				++tier;
			}
		}

		// if merge resume http seeds is not set, we need to clear whatever web
		// seeds we loaded from the .torrent file, because we want whatever's in
		// the resume file to take precedence. If there aren't even any fields in
		// the resume data though, keep the ones from the torrent
		bdecode_node const url_list = rd.dict_find_list("url-list");
		bdecode_node const httpseeds = rd.dict_find_list("httpseeds");
		if (url_list || httpseeds)
		{
			// since we found http seeds in the resume data, they should replace
			// whatever web seeds are specified in the .torrent, by default
			ret.flags |= torrent_flags::override_web_seeds;
		}

		if (url_list)
		{
			for (int i = 0; i < url_list.list_size(); ++i)
			{
				auto url = url_list.list_string_value_at(i);
				if (url.empty()) continue;
				ret.url_seeds.push_back(url.to_string());
			}
		}

		if (httpseeds)
		{
			for (int i = 0; i < httpseeds.list_size(); ++i)
			{
				auto url = httpseeds.list_string_value_at(i);
				if (url.empty()) continue;
				ret.http_seeds.push_back(url.to_string());
			}
		}

		bdecode_node const mt = rd.dict_find_string("merkle tree");
		if (mt && mt.string_length() >= int(sha1_hash::size()))
		{
			ret.merkle_tree.resize(aux::numeric_cast<std::size_t>(mt.string_length()) / sha1_hash::size());
			std::memcpy(ret.merkle_tree.data(), mt.string_ptr()
				, ret.merkle_tree.size() * sha1_hash::size());
		}

		// some sanity checking. Maybe we shouldn't be in seed mode anymore
		if (bdecode_node const pieces = rd.dict_find_string("pieces"))
		{
			char const* pieces_str = pieces.string_ptr();
			int const pieces_len = pieces.string_length();
			ret.have_pieces.resize(pieces_len);
			ret.verified_pieces.resize(pieces_len);
			for (piece_index_t i(0); i < ret.verified_pieces.end_index(); ++i)
			{
				// being in seed mode and missing a piece is not compatible.
				// Leave seed mode if that happens
				if (pieces_str[static_cast<int>(i)] & 1) ret.have_pieces.set_bit(i);
				else ret.have_pieces.clear_bit(i);

				if (pieces_str[static_cast<int>(i)] & 2) ret.verified_pieces.set_bit(i);
				else ret.verified_pieces.clear_bit(i);
			}
		}

		if (bdecode_node const piece_priority = rd.dict_find_string("piece_priority"))
		{
			char const* prio_str = piece_priority.string_ptr();
			ret.piece_priorities.resize(aux::numeric_cast<std::size_t>(piece_priority.string_length()));
			for (std::size_t i = 0; i < ret.piece_priorities.size(); ++i)
			{
				ret.piece_priorities[i] = download_priority_t(aux::clamp(
					static_cast<std::uint8_t>(prio_str[i])
					, static_cast<std::uint8_t>(dont_download)
					, static_cast<std::uint8_t>(top_priority)));
			}
		}

		int const v6_size = 18;
		int const v4_size = 6;
		using namespace libtorrent::detail; // for read_*_endpoint()
		if (bdecode_node const peers_entry = rd.dict_find_string("peers"))
		{
			char const* ptr = peers_entry.string_ptr();
			for (int i = v4_size - 1; i < peers_entry.string_length(); i += v4_size)
				ret.peers.push_back(read_v4_endpoint<tcp::endpoint>(ptr));
		}

		if (bdecode_node const peers_entry = rd.dict_find_string("peers6"))
		{
			char const* ptr = peers_entry.string_ptr();
			for (int i = v6_size - 1; i < peers_entry.string_length(); i += v6_size)
				ret.peers.push_back(read_v6_endpoint<tcp::endpoint>(ptr));
		}

		if (bdecode_node const peers_entry = rd.dict_find_string("banned_peers"))
		{
			char const* ptr = peers_entry.string_ptr();
			for (int i = v4_size; i < peers_entry.string_length(); i += v4_size)
				ret.banned_peers.push_back(read_v4_endpoint<tcp::endpoint>(ptr));
		}

		if (bdecode_node const peers_entry = rd.dict_find_string("banned_peers6"))
		{
			char const* ptr = peers_entry.string_ptr();
			for (int i = v6_size - 1; i < peers_entry.string_length(); i += v6_size)
				ret.banned_peers.push_back(read_v6_endpoint<tcp::endpoint>(ptr));
		}

		// parse unfinished pieces
		if (bdecode_node const unfinished_entry = rd.dict_find_list("unfinished"))
		{
			for (int i = 0; i < unfinished_entry.list_size(); ++i)
			{
				bdecode_node const e = unfinished_entry.list_at(i);
				if (e.type() != bdecode_node::dict_t) continue;
				piece_index_t const piece = piece_index_t(int(e.dict_find_int_value("piece", -1)));
				if (piece < piece_index_t(0)) continue;

				bdecode_node const bitmask = e.dict_find_string("bitmask");
				if (!bitmask || bitmask.string_length() == 0) continue;
				ret.unfinished_pieces[piece].assign(
					bitmask.string_ptr(), bitmask.string_length() * CHAR_BIT);
			}
		}

		// we're loading this torrent from resume data. There's no need to
		// re-save the resume data immediately.
		ret.flags &= ~torrent_flags::need_save_resume;

		return ret;
	}

	add_torrent_params read_resume_data(span<char const> buffer, error_code& ec)
	{
		bdecode_node rd = bdecode(buffer, ec);
		if (ec) return add_torrent_params();

		return read_resume_data(rd, ec);
	}

	add_torrent_params read_resume_data(bdecode_node const& rd)
	{
		error_code ec;
		auto ret = read_resume_data(rd, ec);
		if (ec) throw system_error(ec);
		return ret;
	}

	add_torrent_params read_resume_data(span<char const> buffer)
	{
		error_code ec;
		bdecode_node rd = bdecode(buffer, ec);
		if (ec) throw system_error(ec);

		auto ret = read_resume_data(rd, ec);
		if (ec) throw system_error(ec);
		return ret;
	}
}
