#include "Session.hpp"

#include <algorithm>

using namespace Epistmool::Server;

namespace {
constexpr int kInvalidSessionIndex = -1;
} // namespace

SessionId SessionId::makeInvalid()
{
	return SessionId{
		.index = kInvalidSessionIndex,
	};
}

bool SessionId::isInvalid() const
{
	return index == kInvalidSessionIndex;
}

SessionId Session::getSessionId() const
{
	return mSessionId;
}

const std::vector<ConnectionId>& Session::getConnections() const
{
	return mConnections;
}

Session::Session(SessionId id)
	: mSessionId{ id }
{
}

// TODO delete session if isn't active for N period of time
SessionManager::SessionManager(QObject* parent)
	: QObject(parent)
{
}

Session* SessionManager::findOrCreateSession(SessionId id)
{
	auto it = mSessions.find(id.index);
	if (it != mSessions.end()) {
		return &it->second;
	} else {
		SessionId newId{ mNextIndex++ };
		auto [it, _] = mSessions.insert({ newId.index, Session(newId) });
		return &it->second;
	}
}

Session* SessionManager::findSession(SessionId id)
{
	auto it = mSessions.find(id.index);
	if (it != mSessions.end()) {
		return &it->second;
	} else {
		return nullptr;
	}
}

void SessionManager::addConnection(SessionId id, ConnectionId connId)
{
	// Add session -> connection links
	auto session = findSession(id);
	if (session) {
		auto location = std::lower_bound(
			session->mConnections.begin(),
			session->mConnections.end(),
			connId,
			[](const ConnectionId& a, const ConnectionId& b) -> bool {
				return a.index < b.index;
			});
		session->mConnections.insert(location, connId);
	}

	// Add connection -> session links
	mConnection2SessionMap.insert(connId.index, id.index);
}

void SessionManager::dropConnection(ConnectionId connId)
{
	// Remove session -> connection links
	auto it = mConnection2SessionMap.find(connId.index);
	while (it != mConnection2SessionMap.end() && it.key() == connId.index) {
		auto& connList = mSessions.at(it.value()).mConnections;
		auto range = std::equal_range(
			connList.begin(),
			connList.end(),
			connId,
			[](const ConnectionId& a, const ConnectionId& b) -> bool {
				return a.index < b.index;
			});
		connList.erase(range.first, range.second);

		++it;
	}

	// Remove connection -> sesion links
	mConnection2SessionMap.remove(connId.index);
}