/*
 * Copyright (c)2013-2021 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#ifndef ZT_TOPOLOGY_HPP
#define ZT_TOPOLOGY_HPP

#include "Constants.hpp"
#include "Address.hpp"
#include "Identity.hpp"
#include "Peer.hpp"
#include "Path.hpp"
#include "Mutex.hpp"
#include "InetAddress.hpp"
#include "SharedPtr.hpp"
#include "ScopedPtr.hpp"
#include "Fingerprint.hpp"
#include "Blob.hpp"
#include "FCV.hpp"
#include "Certificate.hpp"
#include "Containers.hpp"
#include "Spinlock.hpp"

namespace ZeroTier {

class RuntimeEnvironment;

/**
 * Database of network topology
 */
class Topology
{
public:
	Topology(const RuntimeEnvironment *renv, void *tPtr, int64_t now);

	/**
	 * Add peer to database
	 *
	 * This will not replace existing peers. In that case the existing peer
	 * record is returned.
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param peer Peer to add
	 * @return New or existing peer (should replace 'peer')
	 */
	SharedPtr< Peer > add(void *tPtr, const SharedPtr< Peer > &peer);

	/**
	 * Get a peer from its address
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param zta ZeroTier address of peer
	 * @param loadFromCached If false do not load from cache if not in memory (default: true)
	 * @return Peer or NULL if not found
	 */
	ZT_INLINE SharedPtr< Peer > peer(void *tPtr, const Address &zta, const bool loadFromCached = true)
	{
		{
			RWMutex::RLock l(m_peers_l);
			Map< Address, SharedPtr< Peer > >::const_iterator ap(m_peers.find(zta));
			if (likely(ap != m_peers.end()))
				return ap->second;
		}
		if (loadFromCached)
			return m_peerFromCached(tPtr, zta);
		return SharedPtr< Peer >();
	}

	/**
	 * Get a Path object for a given local and remote physical address, creating if needed
	 *
	 * @param l Local socket
	 * @param r Remote address
	 * @return Pointer to canonicalized Path object or NULL on error
	 */
	ZT_INLINE SharedPtr< Path > path(const int64_t l, const InetAddress &r)
	{
		const Path::Key k(r);
		{
			RWMutex::RLock lck(m_paths_l);
			Map< Path::Key, SharedPtr< Path > >::const_iterator p(m_paths.find(k));
			if (likely(p != m_paths.end()))
				return p->second;
		}
		return m_newPath(l, r, k);
	}

	/**
	 * Get current best root
	 *
	 * @return Root peer or nullptr if none
	 */
	ZT_INLINE SharedPtr< Peer > root()
	{
		l_bestRoot.lock(); // spinlock
		SharedPtr< Peer > r(m_bestRoot);
		l_bestRoot.unlock();
		return r;
	}

	/**
	 * Get current best root by setting a result parameter
	 *
	 * @param root Set to best root or nullptr if none
	 */
	ZT_INLINE void root(SharedPtr< Peer > &root)
	{
		l_bestRoot.lock(); // spinlock
		root = m_bestRoot;
		l_bestRoot.unlock();
	}

	/**
	 * @param allPeers vector to fill with all current peers
	 */
	void allPeers(Vector< SharedPtr< Peer > > &allPeers, Vector< SharedPtr< Peer > > &rootPeers) const;

	/**
	 * Do periodic tasks such as database cleanup, cert cleanup, root ranking, etc.
	 *
	 * @param tPtr Thread pointer
	 * @param now Current time
	 */
	void doPeriodicTasks(void *tPtr, int64_t now);

	/**
	 * Rank root servers in descending order of quality
	 *
	 * @param now Current time
	 */
	ZT_INLINE void rankRoots(int64_t now)
	{
		Mutex::Lock l(m_roots_l);
		m_rankRoots(now);
	}

	/**
	 * Save all currently known peers to data store
	 *
	 * @param tPtr Thread pointer
	 */
	void saveAll(void *tPtr);

private:
	void m_rankRoots(int64_t now);
	void m_loadCached(void *tPtr, const Address &zta, SharedPtr< Peer > &peer);
	SharedPtr< Peer > m_peerFromCached(void *tPtr, const Address &zta);
	SharedPtr< Path > m_newPath(int64_t l, const InetAddress &r, const Path::Key &k);

	const RuntimeEnvironment *const RR;

	Vector< SharedPtr< Peer > > m_roots;
	Map< Address, SharedPtr< Peer > > m_peers;
	Map< Path::Key, SharedPtr< Path > > m_paths;

	RWMutex m_peers_l; // m_peers
	RWMutex m_paths_l; // m_paths
	Mutex m_roots_l;   // m_roots and m_lastRankedRoots

	SharedPtr< Peer > m_bestRoot;
	Spinlock l_bestRoot;
};

} // namespace ZeroTier

#endif