namespace GameServer.Contents.GameMode.Helper;

using Nettention.Proud;

public class PingLatencyPolicy
{
	public int PingKickThreshold { get; set; } = 600;
	public TimeSpan PingKickDuration { get; set; } = TimeSpan.FromSeconds(30);
}

//=====================================================================
// LatencyChecker - 플레이가 불가능한 핑 지연을 체크한다. super peer와의 핑을 체크
//=====================================================================
public class PingLatencyKicker
{
	public class ClientLatency
	{
		public HostID HostId { get; set; }
		public int PingSum { get; set; }
		public int PingCheckCount { get; set; }
		public DateTime PingCheckBeginTime { get; set; } = DateTime.UtcNow;
		public int PingAverage => PingCheckCount > 0 ? PingSum / PingCheckCount: 0;
	}

	private readonly PingLatencyPolicy m_ping_latency_policy;
	private readonly SortedList<HostID, ClientLatency> m_host_latencies = new();
	private HostID m_group_id;
	private HostID m_super_peer_id;
	private readonly NetServer m_server;

	public PingLatencyKicker(NetServer server, PingLatencyPolicy pingLatencyPolicy)
	{
		m_ping_latency_policy = pingLatencyPolicy;
		m_server = server;
	}

	public void setGroupHostId(HostID groupId)
	{
		m_group_id = groupId;
	}

	public void setSuperPeerId(HostID superPeerId)
	{
		m_super_peer_id = superPeerId;
	}

	//=================================================================
	// 호스트 그룹에 속한 클라이언트의 핑 지연을 체크하여, 게임이 불가한 지연이 발생한 경우 해당 호스트를 반환
	//==============================================================
	public IEnumerable<HostID> shouldKick()
	{
		if (!isValidGroup())
		{
			return [];
		}

		checkAndValidateSuperPeer();

		if (!isValidSuperPeer())
		{
			return [];
		}

		var kick_host_ids = getGroupMemberHostIds().Where(x => checkLatency(x) == true);
		return kick_host_ids;
	}

	public async Task<IEnumerable<HostID>> shouldKickAsync()
	{
		return await Task.Run(shouldKick);
	}

	//=================================================================
	// 핑 지연 체크
	//=================================================================
	private bool checkLatency(HostID hostId)
	{
		var ping_to_super_peer = getP2PRecentPingMs(hostId);
		m_host_latencies.TryGetValue(hostId, out var client_latency);
		if (ping_to_super_peer > m_ping_latency_policy.PingKickThreshold)
		{
			if (client_latency == null)
			{
				client_latency = new ClientLatency
				{
					HostId = hostId, PingSum = 0, PingCheckCount = 0, PingCheckBeginTime = DateTime.UtcNow
				};
				m_host_latencies.Add(hostId, client_latency);
			}
		}

		if (client_latency != null)
		{
			if (client_latency.PingCheckBeginTime + m_ping_latency_policy.PingKickDuration > DateTime.UtcNow)
			{
				if (client_latency.PingAverage > m_ping_latency_policy.PingKickThreshold)
				{
					return true;
				}

				m_host_latencies.Remove(hostId);
			}
		}

		return false;
	}

	private int getP2PRecentPingMs(HostID hostId)
	{
		return m_server.GetP2PRecentPingMs(hostId, m_super_peer_id);
	}

	private IEnumerable<HostID> getGroupMemberHostIds()
	{
		var host_ids = new List<HostID>();
		var group_info = m_server.GetP2PGroupInfo(m_group_id);
		for (int i = 0; i < group_info.members.GetCount(); i++)
		{
			host_ids.Add(group_info.members.At(i));
		}

		return host_ids;
	}

	//=================================================================
	// 호스트 그룹이 삭제됐는 지 확인
	//=================================================================
	private bool isValidGroup()
	{
		if (m_group_id == HostID.HostID_None)
			return false;

		var group_info = m_server.GetP2PGroupInfo(m_group_id);
		if (group_info == null || group_info.members.GetCount() == 0)
		{
			m_group_id = HostID.HostID_None;
			return false;
		}

		return true;
	}

	//=================================================================
	// 수퍼 피어가 퇴장한 경우 등을 체크
	//=================================================================
	private void checkAndValidateSuperPeer()
	{
		// 수퍼 피어가 퇴장한 경우 등을 체크
		if (m_super_peer_id != HostID.HostID_None && m_server.GetClientInfo(m_super_peer_id) == null)
		{
			m_super_peer_id = HostID.HostID_None;
		}
	}

	//=================================================================
	// 수퍼 피어가 설정되어 있는지 체크
	//=================================================================
	private bool isValidSuperPeer()
	{
		return m_super_peer_id != HostID.HostID_None;
	}
}