#include "network.h"

#include "identity.h"

#include <cstring>

#include <ifaddrs.h>
#include <net/if.h>
#include <unistd.h>

using std::scoped_lock;
using std::unique_lock;
using std::unique_ptr;

using namespace erebos;

Server::Server(const Identity & self):
	p(new Priv(self))
{
}

Server::~Server() = default;

Server::Priv::Priv(const Identity & self):
	self(self)
{
	struct ifaddrs * raddrs;
	if (getifaddrs(&raddrs) < 0)
		throw std::system_error(errno, std::generic_category());
	unique_ptr<ifaddrs, void(*)(ifaddrs *)> addrs(raddrs, freeifaddrs);

	for (struct ifaddrs * ifa = addrs.get(); ifa; ifa = ifa->ifa_next) {
		if (ifa->ifa_addr && ifa->ifa_addr->sa_family == AF_INET &&
				ifa->ifa_flags & IFF_BROADCAST) {
			bcastAddresses.push_back(((sockaddr_in*)ifa->ifa_broadaddr)->sin_addr);
		}
	}
	
	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0)
		throw std::system_error(errno, std::generic_category());

	int enable = 1;
	if (setsockopt(sock, SOL_SOCKET, SO_BROADCAST,
				&enable, sizeof(enable)) < 0)
		throw std::system_error(errno, std::generic_category());

	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
				&enable, sizeof(enable)) < 0)
		throw std::system_error(errno, std::generic_category());

	sockaddr_in laddr = {};
	laddr.sin_family = AF_INET;
	laddr.sin_port = htons(discoveryPort);
	if (bind(sock, (sockaddr *) &laddr, sizeof(laddr)) < 0)
		throw std::system_error(errno, std::generic_category());

	threadListen = thread([this] { doListen(); });
	threadAnnounce = thread([this] { doAnnounce(); });
}

Server::Priv::~Priv()
{
	{
		scoped_lock lock(dataMutex);
		finish = true;
	}

	announceCondvar.notify_all();
	threadListen.join();
	threadAnnounce.join();

	if (sock >= 0)
		close(sock);
}

void Server::Priv::doListen()
{
}

void Server::Priv::doAnnounce()
{
	unique_lock<mutex> lock(dataMutex);
	auto lastAnnounce = steady_clock::now() - announceInterval;

	while (!finish) {
		auto now = steady_clock::now();

		if (lastAnnounce + announceInterval < now) {
			TransportHeader header({
				{ TransportHeader::Type::AnnounceSelf, *self.ref() }
			});

			vector<uint8_t> bytes = header.store(self.ref()->storage())->encode();

			for (const auto & in : bcastAddresses) {
				sockaddr_in sin = {};
				sin.sin_family = AF_INET;
				sin.sin_addr = in;
				sin.sin_port = htons(discoveryPort);
				sendto(sock, bytes.data(), bytes.size(), 0, (sockaddr *) &sin, sizeof(sin));
			}

			lastAnnounce += announceInterval * ((now - lastAnnounce) / announceInterval);
		}

		announceCondvar.wait_until(lock, lastAnnounce + announceInterval);
	}
}

optional<TransportHeader> TransportHeader::load(const Ref & ref)
{
	auto rec = ref->asRecord();
	if (!rec)
		return nullopt;

	vector<Item> items;
	for (const auto & item : rec->items()) {
		if (item.name == "ACK") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::Acknowledged,
					.value = *ref,
				});
		} else if (item.name == "REQ") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::DataRequest,
					.value = *ref,
				});
		} else if (item.name == "RSP") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::DataResponse,
					.value = *ref,
				});
		} else if (item.name == "ANN") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::AnnounceSelf,
					.value = *ref,
				});
		} else if (item.name == "ANU") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::AnnounceUpdate,
					.value = *ref,
				});
		} else if (item.name == "CRQ") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::ChannelRequest,
					.value = *ref,
				});
		} else if (item.name == "CAC") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::ChannelAccept,
					.value = *ref,
				});
		} else if (item.name == "STP") {
			if (auto val = item.asText())
				items.emplace_back(Item {
					.type = Type::ServiceType,
					.value = *val,
				});
		} else if (item.name == "SRF") {
			if (auto ref = item.asRef())
				items.emplace_back(Item {
					.type = Type::ServiceRef,
					.value = *ref,
				});
		}
	}

	return TransportHeader { .items = items };
}

Ref TransportHeader::store(const Storage & st) const
{
	vector<Record::Item> ritems;

	for (const auto & item : items) {
		switch (item.type) {
		case Type::Acknowledged:
			ritems.emplace_back("ACK", std::get<Ref>(item.value));
			break;

		case Type::DataRequest:
			ritems.emplace_back("REQ", std::get<Ref>(item.value));
			break;

		case Type::DataResponse:
			ritems.emplace_back("RSP", std::get<Ref>(item.value));
			break;

		case Type::AnnounceSelf:
			ritems.emplace_back("ANN", std::get<Ref>(item.value));
			break;

		case Type::AnnounceUpdate:
			ritems.emplace_back("ANU", std::get<Ref>(item.value));
			break;

		case Type::ChannelRequest:
			ritems.emplace_back("CRQ", std::get<Ref>(item.value));
			break;

		case Type::ChannelAccept:
			ritems.emplace_back("CAC", std::get<Ref>(item.value));
			break;

		case Type::ServiceType:
			ritems.emplace_back("STP", std::get<string>(item.value));
			break;

		case Type::ServiceRef:
			ritems.emplace_back("SRF", std::get<Ref>(item.value));
			break;
		}
	}

	return st.storeObject(Record(std::move(ritems)));
}