/*

Copyright (c) 2008-2015, 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.

*/

#ifndef TORRENT_DISABLE_EXTENSIONS

#include "libtorrent/aux_/disable_warnings_push.hpp"

#include <boost/shared_ptr.hpp>
#include <boost/bind.hpp>

#include <vector>
#include <utility>
#include <numeric>
#include <cstdio>

#include "libtorrent/aux_/disable_warnings_pop.hpp"

#include "libtorrent/peer_connection.hpp"
#include "libtorrent/bt_peer_connection.hpp"
#include "libtorrent/peer_connection_handle.hpp"
#include "libtorrent/hasher.hpp"
#include "libtorrent/bencode.hpp"
#include "libtorrent/torrent.hpp"
#include "libtorrent/extensions.hpp"
#include "libtorrent/extensions/lt_trackers.hpp"
#include "libtorrent/alert_types.hpp"
#include "libtorrent/io.hpp"
#include "libtorrent/parse_url.hpp"
#include "libtorrent/torrent_handle.hpp"

namespace libtorrent { namespace
{

	bool send_tracker(announce_entry const& e)
	{
		// max_fails == 0 means that it's one
		// of the trackers from the trackers
		// from the torrent file
		return e.fail_limit == 0 || e.verified;
	}

	struct lt_tracker_plugin : torrent_plugin
	{
		lt_tracker_plugin(torrent& t)
			: m_torrent(t)
			, m_updates(0)
			, m_2_minutes(110)
			, m_num_trackers(0)
		{
			m_old_trackers = t.trackers();
			update_list_hash();
		}

		virtual boost::shared_ptr<peer_plugin> new_connection(
			peer_connection_handle const& pc);
		
		virtual void tick()
		{
			if (m_2_minutes++ < 120) return;
			m_2_minutes = 0;

			// build tracker diff
			entry tex;
			entry::list_type& added = tex["added"].list();
			std::vector<announce_entry> const& trackers = m_torrent.trackers();
			for (std::vector<announce_entry>::const_iterator i = trackers.begin()
				, end(trackers.end()); i != end; ++i)
			{
				std::vector<announce_entry>::const_iterator k = std::find_if(
					m_old_trackers.begin(), m_old_trackers.end()
					, boost::bind(&announce_entry::url, _1) == i->url);
				if (k != m_old_trackers.end()) continue;
				if (!send_tracker(*i)) continue;
				m_old_trackers.push_back(*i);
				++m_updates;
				added.push_back(i->url);
			}
			m_lt_trackers_msg.clear();
			bencode(std::back_inserter(m_lt_trackers_msg), tex);
			if (m_updates > 0) update_list_hash();
		}

		void update_list_hash()
		{
			std::vector<std::string> canonical_list;
			std::transform(m_old_trackers.begin(), m_old_trackers.end(), back_inserter(canonical_list)
				, boost::bind(&announce_entry::url, _1));
			std::sort(canonical_list.begin(), canonical_list.end());

			hasher h;
			std::for_each(canonical_list.begin(), canonical_list.end()
				, boost::bind(&hasher::update, &h, _1));
			m_list_hash = h.final();
		}

		int num_updates() const { return m_updates; }

		std::vector<char> const& get_lt_tex_msg() const { return m_lt_trackers_msg; }

		sha1_hash const& list_hash() const { return m_list_hash; }

		std::vector<announce_entry> const& trackers() const { return m_old_trackers; }

		void increment_tracker_counter() { m_num_trackers++; }
		int num_tex_trackers() const { return m_num_trackers; }

	private:
		torrent& m_torrent;
		std::vector<announce_entry> m_old_trackers;
		int m_updates;
		int m_2_minutes;
		std::vector<char> m_lt_trackers_msg;
		sha1_hash m_list_hash;
		int m_num_trackers;
	};


	struct lt_tracker_peer_plugin : peer_plugin
	{
		lt_tracker_peer_plugin(torrent& t, bt_peer_connection& pc, lt_tracker_plugin& tp)
			: m_message_index(0)
			, m_torrent(t)
			, m_pc(pc)
			, m_tp(tp)
			, m_2_minutes(115)
			, m_full_list(true)
		{}

		// can add entries to the extension handshake
		virtual void add_handshake(entry& h)
		{
			entry& messages = h["m"];
			messages["lt_tex"] = 19;
			h["tr"] = m_tp.list_hash().to_string();
		}

		// called when the extension handshake from the other end is received
		virtual bool on_extension_handshake(bdecode_node const& h)
		{
			m_message_index = 0;
			if (h.type() != bdecode_node::dict_t) return false;
			bdecode_node messages = h.dict_find("m");
			if (!messages || messages.type() != bdecode_node::dict_t) return false;

			int index = int(messages.dict_find_int_value("lt_tex", -1));
			if (index == -1) return false;
			m_message_index = index;

			// if we have the same tracker list, don't bother sending the
			// full list. Just send deltas
			std::string tracker_list_hash = h.dict_find_string_value("tr");
			if (tracker_list_hash.size() == 20
				&& sha1_hash(tracker_list_hash) == m_tp.list_hash())
			{
				m_full_list = false;
			}
			return true;
		}

		virtual bool on_extended(int /* length */
			, int extended_msg, buffer::const_interval body)
		{
			if (extended_msg != 19) return false;
			if (m_message_index == 0) return false;
			if (!m_pc.packet_finished()) return true;

			bdecode_node msg;
			error_code ec;
			int ret = bdecode(body.begin, body.end, msg, ec);
			if (ret != 0 || msg.type() != bdecode_node::dict_t)
			{
				m_pc.disconnect(errors::invalid_lt_tracker_message, op_bittorrent, 2);
				return true;
			}

			bdecode_node added = msg.dict_find_list("added");

			// invalid tex message
			if (added == 0)
			{
#ifndef TORRENT_DISABLE_LOGGING
				m_pc.peer_log(peer_log_alert::incoming_message, "LT_TEX"
					, "NOT A DICTIONARY");
#endif
				return true;
			}

			if (m_tp.num_tex_trackers() >= 50)
			{
#ifndef TORRENT_DISABLE_LOGGING
				m_pc.peer_log(peer_log_alert::incoming_message, "LT_TEX"
					, "we already have %d trackers from tex, don't add any more"
					, m_tp.num_tex_trackers());
#endif
				return true;
			}

#ifndef TORRENT_DISABLE_LOGGING
			m_pc.peer_log(peer_log_alert::incoming_message, "LT_TEX");
#endif

			for (int i = 0; i < added.list_size(); ++i)
			{
				announce_entry e(added.list_string_value_at(i));
				if (e.url.empty()) continue;

				// ignore urls with binary data in them
				if (need_encoding(e.url.c_str(), e.url.size())) continue;

				// ignore invalid URLs
				error_code err;
				std::string protocol;
				std::string auth;
				std::string hostname;
				int port;
				std::string path;
				boost::tie(protocol, auth, hostname, port, path)
					= parse_url_components(e.url, err);
				if (err) continue;

				// ignore unknown protocols
				if (protocol != "udp" && protocol != "http" && protocol != "https")
					continue;

				// ignore invalid ports
				if (port == 0)
					continue;

				if (m_tp.num_tex_trackers() >= 50)
					break;

				e.fail_limit = 1;
				e.send_stats = false;
				e.source = announce_entry::source_tex;
				if (m_torrent.add_tracker(e))
					m_tp.increment_tracker_counter();

#ifndef TORRENT_DISABLE_LOGGING
				m_pc.peer_log(peer_log_alert::info, "LT_TEX", "added: %s", e.url.c_str());
#endif
			}
			return true;
		}

		virtual void tick()
		{
			// no handshake yet
			if (!m_message_index) return;
			if (++m_2_minutes <= 120) return;
			m_2_minutes = 0;

			if (m_full_list)
			{
				if (send_full_tex_list())
					m_full_list = false;
			}
			else
			{
				send_lt_tex_diff();
			}
		}

	private:

		void send_lt_tex_diff()
		{
			// if there's no change in out tracker set, don't send anything
			if (m_tp.num_updates() == 0) return;

			if (!m_torrent.valid_metadata() || m_torrent.torrent_file().priv())
				return;

			std::vector<char> const& tex_msg = m_tp.get_lt_tex_msg();

			char msg[6];
			char* ptr = msg;

			detail::write_uint32(1 + 1 + tex_msg.size(), ptr);
			detail::write_uint8(bt_peer_connection::msg_extended, ptr);
			detail::write_uint8(m_message_index, ptr);
			m_pc.send_buffer(msg, sizeof(msg));
			m_pc.send_buffer(&tex_msg[0], tex_msg.size());
			m_pc.setup_send();
		}

		bool send_full_tex_list() const
		{
			if (m_tp.trackers().empty()) return false;

			if (!m_torrent.valid_metadata() || m_torrent.torrent_file().priv())
				return false;

#ifndef TORRENT_DISABLE_LOGGING
			m_pc.peer_log(peer_log_alert::outgoing_message, "LT_TEX");
#endif
			entry tex;
			entry::list_type& added = tex["added"].list();
			for (std::vector<announce_entry>::const_iterator i = m_tp.trackers().begin()
				, end(m_tp.trackers().end()); i != end; ++i)
			{
				if (!send_tracker(*i)) continue;
				added.push_back(i->url);
#ifndef TORRENT_DISABLE_LOGGING
				m_pc.peer_log(peer_log_alert::info, "LT_TEX"
					, "sending: %s", i->url.c_str());
#endif
			}
			std::vector<char> tex_msg;
			bencode(std::back_inserter(tex_msg), tex);

			char msg[6];
			char* ptr = msg;

			detail::write_uint32(1 + 1 + tex_msg.size(), ptr);
			detail::write_uint8(bt_peer_connection::msg_extended, ptr);
			detail::write_uint8(m_message_index, ptr);
			m_pc.send_buffer(msg, sizeof(msg));
			m_pc.send_buffer(&tex_msg[0], tex_msg.size());
			m_pc.setup_send();

			return true;
		}

		// this is the message index the remote peer uses
		// for metadata extension messages.
		int m_message_index;

		torrent& m_torrent;
		bt_peer_connection& m_pc;
		lt_tracker_plugin& m_tp;

		int m_2_minutes;
		bool m_full_list;
	};

	boost::shared_ptr<peer_plugin> lt_tracker_plugin::new_connection(
		peer_connection_handle const& pc)
	{
		if (pc.type() != peer_connection::bittorrent_connection)
			return boost::shared_ptr<peer_plugin>();

		if (m_torrent.valid_metadata() && m_torrent.torrent_file().priv())
			return boost::shared_ptr<peer_plugin>();

		bt_peer_connection* c = static_cast<bt_peer_connection*>(pc.native_handle().get());
		return boost::shared_ptr<peer_plugin>(new lt_tracker_peer_plugin(m_torrent, *c, *this));
	}

} }

namespace libtorrent
{

	boost::shared_ptr<torrent_plugin> TORRENT_EXPORT create_lt_trackers_plugin(torrent_handle const& th, void*)
	{
		torrent* t = th.native_handle().get();
		if (t->valid_metadata() && t->torrent_file().priv()) return boost::shared_ptr<torrent_plugin>();
		return boost::shared_ptr<torrent_plugin>(new lt_tracker_plugin(*t));
	}

}

#endif

