#include "node.hpp"

#include "cmix.h"
#include "bignum.h"

#include "logging.hpp"

#include <numeric>

using namespace boost::asio::ip;

Node::Node(ListenSettings const& listen_settings, NodeNetworkSettings network_settings)
: io_service()
, ssl_ctx(std::make_shared<boost::asio::ssl::context>(boost::asio::ssl::context::sslv23))
, server(io_service, listen_settings, ssl_ctx, [this](std::unique_ptr<boost::asio::ssl::stream<boost::asio::ip::tcp::socket>>&& socket, std::shared_ptr<boost::asio::ssl::context> ctx){accept_handler(std::move(socket), ctx);})
, clients()
, data()
, network_settings(network_settings)
, prev_node(SSLReceiver(std::unique_ptr<boost::asio::ssl::stream<tcp::socket>>(new boost::asio::ssl::stream<boost::asio::ip::tcp::socket>(io_service, *ssl_ctx))))
, next_node(SSLSender(std::unique_ptr<boost::asio::ssl::stream<tcp::socket>>(new boost::asio::ssl::stream<boost::asio::ip::tcp::socket>(io_service, *ssl_ctx))))
, cmix_ctx(initialize_cmix_context(get_implementation()))
, precomputation_data()
, shutting_down(false)
{
	initialize_keypair(&cmix_ctx);
	
	GOOGLE_PROTOBUF_VERIFY_VERSION;

	if(network_settings.is_first) {
		connect_to_next_node();
	}
}

Node::~Node() {
	deinitialize(&cmix_ctx);
}

void Node::run() {
	io_service.run();
}

void Node::accept_handler(std::unique_ptr<boost::asio::ssl::stream<boost::asio::ip::tcp::socket>>&& socket, std::shared_ptr<boost::asio::ssl::context> ctx)
{
	Purgatory::iterator it = purgatory.emplace(purgatory.end(), std::move(socket));
	purgatory.back().on_done(
		[this, it]() {
			purgatory.erase(it);
		}
	);

	it->async_receive([this, it](cmix_proto::CMixMessage message) {
		handle_message(it, message);
	});
}

void Node::connect_to_next_node()
{
	if(!network_settings.certdir.empty()) {
		ssl_ctx->add_verify_path(network_settings.certdir);
	}
	
	auto on_connect = [this](){
		BOOST_LOG_TRIVIAL(trace) << "Connected to next_node";
		next_node.async_send(cmix_proto::ImANode());
	};
	
	next_node.async_connect(network_settings.next_host, network_settings.next_port, on_connect);
}

void Node::start_initialisation() {
	cmix_proto::Initialization init;
	
	size_t len = get_group_element_array_size(&cmix_ctx);
	init.mutable_public_share()->resize(len);
	
	get_public_key(&cmix_ctx, &(*init.mutable_public_share())[0]);
	
	BOOST_LOG_TRIVIAL(trace) << "Sending intialization as first node";
	next_node.async_send(init);
}


void Node::handle_node_initialization(const cmix_proto::Initialization& init)
{
	if(network_settings.is_first) {
		set_network_key(&cmix_ctx, init.public_share().data(), init.public_share().size());
	
		cmix_proto::SecretKey sec;
		sec.set_secret_key(init.public_share().data(), init.public_share().size());
		
		next_node.async_send(sec);
	} else {
		size_t len = get_group_element_array_size(&cmix_ctx);
		
		cmix_proto::Initialization n_init;
		n_init.mutable_public_share()->resize(len);
		add_public_share(&cmix_ctx, &(*n_init.mutable_public_share())[0], init.public_share().data());
	
		BOOST_LOG_TRIVIAL(trace) << "Sending intialization";
		next_node.async_send(n_init);
	}
}

void Node::handle_node_secretkey(cmix_proto::SecretKey const& secret)
{
	std::string share = secret.secret_key();
	
	set_network_key(&cmix_ctx, secret.secret_key().data(), secret.secret_key().size());
	
	if(network_settings.is_first) {
		start_precomputation();
	} else {
		next_node.async_send(secret);
	}
}

template <typename T>
cmix_proto::PrePre fill_precomputation_pre_message(CMixContext& ctx, T const& rs, T const& ms) {
	if(start_mix(&ctx, rs.size()) != no_error) {
		exit(-1);
	}
	
	if(initialize_mix_randomness(&ctx) != no_error) {
		exit(-1);
	}
	
	cmix_proto::PrePre prepre;
	
	for(size_t i = 0; i < ctx.nr_participants; ++i) {
		size_t len = get_group_element_array_size(&ctx);
		
		prepre.mutable_m_er(i)->resize(len);
		prepre.mutable_r_er(i)->resize(len);
		
		if(encrypt_r_and_multiply(
			&ctx, 
			&(*prepre.mutable_r_er(i))[0],
			&(*prepre.mutable_m_er(i))[0],
			rs.Get(i).data(),
			ms.Get(i).data(),
			i
		) != no_error) {
			exit(-1);
		}
	}
	return prepre;
}

template <typename T>
cmix_proto::PreMix fill_precomputation_mix_message(CMixContext const& ctx, T const& rs, T const& ms) {
	cmix_proto::PreMix premix;
	for(size_t i = 0; i < ctx.nr_participants; ++i) {
		auto new_pos = ctx.permutation[i];
		size_t el_len = get_group_element_array_size(&ctx);
		
		premix.mutable_r_epirs(new_pos)->resize(el_len);
		premix.mutable_m_epirs(new_pos)->resize(el_len);
		
		multiply_s(
			&ctx,
			&(*premix.mutable_r_epirs(new_pos))[0],
			&(*premix.mutable_m_epirs(new_pos))[0],
			rs.Get(i).data(),
			ms.Get(i).data(),
			i
		);
	}
	return premix;
}

template <typename T>
cmix_proto::PrePost fill_precomputation_post_message(CMixContext& ctx, T const& rs, T const& ms) {
	cmix_proto::PrePost prepost;
	
	for(size_t i = 0; i < ctx.nr_participants; ++i) {
		post_process(&ctx, rs.Get(i).data(), ms.Get(i).data(), i);
		*prepost.mutable_r_epirs(i) = rs.Get(i);
		*prepost.mutable_m_epirs(i) = ms.Get(i);
	}
	
	return prepost;
}

void Node::handle_node_prepre(cmix_proto::PrePre const& pre) {
	if(network_settings.is_first) {
		cmix_proto::PreMix premix = fill_precomputation_mix_message(cmix_ctx, pre.r_er(), pre.m_er());
		next_node.async_send(premix);
	} else {
		cmix_proto::PrePre prepre = fill_precomputation_pre_message(cmix_ctx, pre.r_er(), pre.m_er());
		next_node.async_send(prepre);
	}
}

void Node::handle_node_premix(cmix_proto::PreMix const& premix) {
	if(network_settings.is_first) {
		cmix_proto::PrePost prepost = fill_precomputation_post_message(cmix_ctx, premix.r_epirs(), premix.m_epirs());
		next_node.async_send(prepost);	
	} else {
		cmix_proto::PreMix n_premix = fill_precomputation_mix_message(cmix_ctx, premix.r_epirs(), premix.m_epirs());
		next_node.async_send(n_premix);
	}
}

void Node::handle_node_prepost(cmix_proto::PrePost const& prepost) {
	if(network_settings.is_first) {
		
	} else {
		cmix_proto::PrePost n_prepost = fill_precomputation_post_message(cmix_ctx, prepost.r_epirs(), prepost.m_epirs());
		next_node.async_send(n_prepost);
	}
}

void Node::handle_node_message(cmix_proto::CMixMessage message)
{
	switch(message.contents_case()) {
		case cmix_proto::CMixMessage::ContentsCase::kInitialization: {
			BOOST_LOG_TRIVIAL(trace) << "Handling initialization";
			handle_node_initialization(message.initialization());
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kBye: {
			BOOST_LOG_TRIVIAL(trace) << "Handling bye";
			//Todo: find a nice way to handle network shutdown.
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kSecretkey: {
			BOOST_LOG_TRIVIAL(trace) << "Handling SecretKey";
			handle_node_secretkey(message.secretkey());
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kPrepre: {
			BOOST_LOG_TRIVIAL(trace) << "Handling PrePre";
			handle_node_prepre(message.prepre());
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kPremix: {
			BOOST_LOG_TRIVIAL(trace) << "Handling PreMix";
			handle_node_premix(message.premix());
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kPrepost: {
			BOOST_LOG_TRIVIAL(trace) << "Handling PrePost";
			handle_node_prepost(message.prepost());
			break;
		}
		default: {
			BOOST_LOG_TRIVIAL(error) << "handle_node_message: CMixMessage contains unknown contents.";
		}
	}
	prev_node.async_receive([this](cmix_proto::CMixMessage message) {
		handle_node_message(message);
	});
}

void Node::handle_client_keyexchange(ClientConnections::key_type handle, cmix_proto::KeyExchange ke) {
	CMixClientData d;
	
	size_t len = get_group_element_array_size(&cmix_ctx);
	
	cmix_proto::KeyExchange nke;
	nke.mutable_public_key()->resize(len);
	nke.mutable_value()->resize(len);
	
	key_exchange(&cmix_ctx, &d.shared_value.shared, &(*nke.mutable_public_key())[0], &(*nke.mutable_value())[0], ke.public_key().data(), ke.value().data());
	
	data[handle] = d;
	
	clients.at(handle).async_send(nke);
}

void Node::handle_client_bye(ClientConnections::key_type handle, cmix_proto::Bye)
{
	clients.at(handle).close();
	clients.erase(handle);
}

void Node::handle_client_message(ClientConnections::key_type handle, cmix_proto::CMixMessage message)
{
	switch(message.contents_case()) {
		case cmix_proto::CMixMessage::ContentsCase::kKeyexchange: {
			BOOST_LOG_TRIVIAL(trace) << "Handling keyexchange";
			handle_client_keyexchange(handle, message.keyexchange());
			break;
		}
		case cmix_proto::CMixMessage::ContentsCase::kBye: {
			BOOST_LOG_TRIVIAL(trace) << "Handling bye";
			handle_client_bye(handle, message.bye());
			return;
		}
		default: {
			BOOST_LOG_TRIVIAL(error) << "handle_client_message: CMixMessage contains unknown contents.";
		}
	}
	clients.at(handle).async_receive([this, handle](cmix_proto::CMixMessage message){
		handle_client_message(handle, message);
	});
}

void Node::handle_imanode(Purgatory::iterator handle) {
	handle->on_done([]{});
	prev_node = std::move(*handle);
	purgatory.erase(handle);
	
	if(network_settings.is_first) {
		start_initialisation();
	} else {
		connect_to_next_node();
	}
	
	prev_node.async_receive([this](cmix_proto::CMixMessage message){
		handle_node_message(message);
	});
}

void Node::handle_imaclient(Purgatory::iterator handle, cmix_proto::ImAClient c) {
	std::string client_id = c.id();
	clients.emplace(c.id(), std::move(*handle));
	clients.at(c.id()).on_done([this, client_id]{
		clients.erase(client_id);
	});
	purgatory.erase(handle);
	clients.at(c.id()).async_send(cmix_proto::NodeReady());
	clients.at(c.id()).async_receive([this, client_id](cmix_proto::CMixMessage message) {
		handle_client_message(client_id, message);
	});
}

void Node::handle_message(Purgatory::iterator handle, cmix_proto::CMixMessage message)
{
	switch(message.contents_case()) {
		case cmix_proto::CMixMessage::ContentsCase::kImanode: {
			BOOST_LOG_TRIVIAL(trace) << "Handling imanode";
			handle_imanode(handle);
			return;
		}
		case cmix_proto::CMixMessage::ContentsCase::kImaclient: {
			BOOST_LOG_TRIVIAL(trace) << "Handling imaclient";
			handle_imaclient(handle, message.imaclient());
			return;
		}
		default: {
			BOOST_LOG_TRIVIAL(error) << "handle_message: CMixMessage contains unknown contents.";
		}
	}
	
	handle->close();
	purgatory.erase(handle);
}

void Node::start_precomputation() {
	if(start_mix(&cmix_ctx, clients.size()) != no_error) {
		exit(-1);
	}
	
	if(initialize_mix_randomness(&cmix_ctx) != no_error) {
		exit(-1);
	}
	
	cmix_proto::PrePre prepre;
	
	for(size_t i = 0; i < cmix_ctx.nr_participants; ++i) {
		size_t len = get_group_element_array_size(&cmix_ctx);
		
		prepre.mutable_r_er(i)->resize(len);
		prepre.mutable_m_er(i)->resize(len);
		
		if(encrypt_r(&cmix_ctx, &(*prepre.mutable_r_er(i))[0], &(*prepre.mutable_m_er(i))[0], i) != no_error) {
			exit(-1);
		}
	}
	
	next_node.async_send(prepre);
}