using System;
using System.Collections.Generic;

namespace Luneraria.Core
{
    /// <summary>
    /// Authoritative network session (port of scripts/luneraria/net/lune_session.gd, protocol 4).
    /// The host owns LuneMatch and every simulation result. Clients send intents only and show the
    /// host's combat through snapshots; they never simulate a combat themselves. The peer id maps to
    /// exactly one seat; a client never chooses another player's slot. A disconnect hands the seat to
    /// a bot. It never destroys a core and never migrates the host. Rejoin: a client that says hello
    /// with the name of a departed seat gets that seat back while it is still bot-held (no accounts,
    /// so the display name is the only key). Offline runs the same code path as a local host with
    /// bot-filled free seats. The transport (ENet in Godot, sockets in Unity) is a link; this class
    /// only speaks kinds and payloads and can be tested in process.
    /// </summary>
    public sealed class LuneSession
    {
        public LuneRole Role = LuneRole.Offline;
        public LuneMatch MatchState;
        public int LocalSlot = -1;
        public string DisplayName = "";
        /// <summary>slot → peer id (1 = host). Absent slots are bots owned by the host.</summary>
        public readonly Dictionary<int, int> SeatPeers = new Dictionary<int, int>();
        public readonly List<LobbyEntry> Lobby = new List<LobbyEntry>();
        /// <summary>Display name → slot of a peer that left; used for rejoining.</summary>
        public readonly Dictionary<string, int> Departed = new Dictionary<string, int>();
        public string LastError = "";
        public bool Connected;
        /// <summary>Client-side counters (tests and diagnostics).</summary>
        public int FramesReceived;
        public int StatesReceived;
        /// <summary>Optional wire; null in offline and pure protocol tests.</summary>
        public ILuneNetLink Link;

        public event Action LobbyChanged;
        public event Action MatchResetup;
        public event Action<string, bool> SessionMessage;
        public event Action<Phase, int> PhaseAnnounced;
        public event Action StateReceived;
        public event Action HostLost;

        int _sentUnitId;
        double _frameClock;
        int _frameSerial;
        int _lastFrameSerial = -1;
        double _lastFrameTime;
        readonly Dictionary<int, LuneUnit> _mirror = new Dictionary<int, LuneUnit>();
        /// <summary>slot → round a bot already planned; a bot seat plans exactly once per planning phase.</summary>
        readonly Dictionary<int, int> _botPlanned = new Dictionary<int, int>();

        /// <summary>Client interpolation factor between the last two snapshots.</summary>
        public double LastFrameTime { get { return _lastFrameTime; } }

        public bool IsAuthority() { return Role != LuneRole.Client; }

        public bool IsNetworked() { return Role != LuneRole.Offline; }

        public string DisplayNameFor(int slot)
        {
            if (MatchState != null && slot >= 0 && slot < MatchState.Players.Count)
                return MatchState.Players[slot].Name;
            return string.Format("Slot {0}", slot);
        }

        public int SeatOfPeer(int peer)
        {
            foreach (KeyValuePair<int, int> pair in SeatPeers)
            {
                if (pair.Value == peer)
                    return pair.Key;
            }
            return -1;
        }

        // ---------------------------------------------------------------- setup
        public void SetupMatch(MatchOptions options)
        {
            MatchState = new LuneMatch();
            MatchState.Setup(options);
            _mirror.Clear();
            _botPlanned.Clear();
            if (IsAuthority())
                ApplySeats();
            MatchResetup?.Invoke();
            AnnouncePhase();
        }

        /// <summary>Seated peers are humans: they must ready up themselves and carry their lobby name.</summary>
        void ApplySeats()
        {
            foreach (Player player in MatchState.Players)
            {
                int slot = player.Slot;
                bool human = SeatPeers.ContainsKey(slot);
                player.IsHuman = human;
                if (MatchState.Phase == Phase.Planning)
                    player.Ready = !human;
                if (human && SeatPeers[slot] != 1)
                    player.Name = LobbyName(slot, player.Name);
            }
        }

        string LobbyName(int slot, string fallback)
        {
            foreach (LobbyEntry entry in Lobby)
            {
                if (entry.Slot == slot && !entry.Bot)
                    return entry.Name;
            }
            return fallback;
        }

        void AnnouncePhase()
        {
            if (MatchState == null)
                return;
            PhaseAnnounced?.Invoke(MatchState.Phase, MatchState.RoundNumber);
        }

        // ---------------------------------------------------------------- start modes
        public void HostOffline(int humanSlot, MatchOptions options)
        {
            Role = LuneRole.Offline;
            Connected = true;
            LocalSlot = humanSlot;
            SeatPeers.Clear();
            if (humanSlot >= 0)
                SeatPeers[humanSlot] = 1;
            Lobby.Clear();
            Departed.Clear();
            if (humanSlot >= 0)
                Lobby.Add(new LobbyEntry { Peer = 1, Slot = humanSlot, Name = "Du", Ready = false, Bot = false });
            for (int slot = 0; slot < 6; slot++)
            {
                if (slot != humanSlot)
                    Lobby.Add(new LobbyEntry { Peer = 0, Slot = slot, Name = "Bot " + slot, Ready = true, Bot = true });
            }
            options.HumanSlot = humanSlot;
            SetupMatch(options);
        }

        /// <summary>Host over an already listening link (sockets or loopback). Peer 1 is this host.</summary>
        public bool HostNetwork(MatchOptions options, string hostName)
        {
            if (Link == null)
            {
                LastError = "Kein Netzwerk-Transport gebunden.";
                return false;
            }
            Role = LuneRole.Host;
            Connected = true;
            DisplayName = hostName;
            int human = options.HumanSlot >= 0 ? options.HumanSlot : 0;
            LocalSlot = human;
            SeatPeers.Clear();
            SeatPeers[human] = 1;
            Departed.Clear();
            Lobby.Clear();
            Lobby.Add(new LobbyEntry { Peer = 1, Slot = human, Name = hostName, Ready = false, Bot = false });
            for (int slot = 0; slot < 6; slot++)
            {
                if (slot != human)
                    Lobby.Add(new LobbyEntry { Peer = 0, Slot = slot, Name = "Bot", Ready = true, Bot = true });
            }
            options.HumanSlot = human;
            SetupMatch(options);
            BroadcastLobby();
            return true;
        }

        /// <summary>Client over a connected link. The hello goes out once the transport is up.</summary>
        public bool JoinNetwork(string guestName)
        {
            if (Link == null)
            {
                LastError = "Kein Netzwerk-Transport gebunden.";
                return false;
            }
            Role = LuneRole.Client;
            Connected = false;
            LocalSlot = -1;
            DisplayName = guestName;
            return true;
        }

        /// <summary>Client: the transport finished the handshake; send hello with protocol and name.</summary>
        public void OnClientConnected()
        {
            Connected = true;
            SessionMessage?.Invoke("Mit dem Host verbunden.", false);
            Link?.Send(1, LuneNet.KHello, new object[] { LuneNet.Protocol, DisplayName });
        }

        public void OnConnectionFailed()
        {
            LastError = "Verbindung zum Host fehlgeschlagen.";
            Connected = false;
            SessionMessage?.Invoke(LastError, true);
            HostLost?.Invoke();
        }

        public void OnServerLost()
        {
            LastError = "Host hat die Verbindung getrennt.";
            Connected = false;
            SessionMessage?.Invoke(LastError, true);
            HostLost?.Invoke();
        }

        public void Close()
        {
            Link = null;
            Role = LuneRole.Offline;
            Connected = false;
            SeatPeers.Clear();
            Lobby.Clear();
            Departed.Clear();
        }

        // ---------------------------------------------------------------- intents
        public SessionResult Submit(Command command)
        {
            if (MatchState == null || MatchState.Phase != Phase.Planning)
                return new SessionResult(false, "Keine Planung.");
            if (Role == LuneRole.Client)
            {
                if (LocalSlot < 0)
                    return new SessionResult(false, "Kein Sitzplatz.");
                Link?.Send(1, LuneNet.KSubmit, new object[] { LocalSlot, command });
                return new SessionResult(true, "Befehl gesendet.", true);
            }
            return HostCommand(1, LocalSlot, command);
        }

        public void ReadyUp()
        {
            if (MatchState == null)
                return;
            if (Role == LuneRole.Client)
            {
                Link?.Send(1, LuneNet.KReady, new object[] { LocalSlot });
                return;
            }
            HostReady(LocalSlot);
        }

        /// <summary>
        /// Testable host entry: peer must own slot. Duplicate submits of a purchase are rejected by
        /// LuneMatch through unique uids and gold, not by packet identity. A seat that reported ready
        /// has committed its plan; later commands are refused.
        /// </summary>
        public SessionResult HostCommand(int peer, int slot, Command command)
        {
            if (!IsAuthority() || MatchState == null)
                return new SessionResult(false, "Keine Autorität.");
            if (SeatOfPeer(peer) < 0 || SeatOfPeer(peer) != slot)
                return Answer(peer, slot, new SessionResult(false, "Fremder Sitz oder ungültige Einheiten-ID."));
            if (MatchState.Phase != Phase.Planning)
                return Answer(peer, slot, new SessionResult(false, "Veralteter Befehl (Planung vorbei)."));
            if (MatchState.Players[slot].Ready)
                return Answer(peer, slot, new SessionResult(false, "Bereits bereit gemeldet – die Planung ist verbindlich."));
            SessionResult result;
            if (command != null && command.Type == "undo")
                result = FromCore(MatchState.Undo(slot));
            else
                result = FromCore(MatchState.Submit(slot, command));
            Answer(peer, slot, result);
            BroadcastState();
            return result;
        }

        static SessionResult FromCore(CommandResult core)
        {
            return new SessionResult(core.Ok, core.Message);
        }

        SessionResult Answer(int peer, int slot, SessionResult result)
        {
            if (Role == LuneRole.Host && peer > 1 && Link != null)
                Link.Send(peer, LuneNet.KFeedback, new object[] { slot, result.Ok, result.Message });
            return result;
        }

        public void HostReady(int slot)
        {
            if (!IsAuthority() || MatchState == null || MatchState.Phase != Phase.Planning)
                return;
            MatchState.SetReady(slot);
            foreach (LobbyEntry entry in Lobby)
            {
                if (EntrySlot(entry) == slot)
                    entry.Ready = true;
            }
            BroadcastLobby();
            if (MatchState.AllReady())
                HostBeginCombat();
            else
                BroadcastState();
        }

        static int EntrySlot(LobbyEntry entry) { return entry.Slot; }

        public void PlanBotSeats()
        {
            if (!IsAuthority() || MatchState == null || MatchState.Phase != Phase.Planning)
                return;
            for (int slot = 0; slot < 6; slot++)
            {
                if (!SeatPeers.ContainsKey(slot))
                    PlanBot(slot);
            }
        }

        void PlanBot(int slot)
        {
            int planned;
            if (_botPlanned.TryGetValue(slot, out planned) && planned == MatchState.RoundNumber)
            {
                MatchState.SetReady(slot);
                return;
            }
            _botPlanned[slot] = MatchState.RoundNumber;
            LuneBot.Plan(MatchState, slot);
        }

        public void HostBeginCombat()
        {
            if (!IsAuthority() || MatchState == null || MatchState.Phase != Phase.Planning)
                return;
            PlanBotSeats();
            MatchState.BeginCombat();
            _sentUnitId = 0;
            _frameClock = 0.0;
            AnnouncePhase();
            if (Role == LuneRole.Host)
            {
                BroadcastState();
                Broadcast(LuneNet.KCombatBegin, new object[] { MatchState.RoundNumber, NewUnitRecords(), BuildingHpArray() });
            }
        }

        /// <summary>Host: call once per rendered frame while combat runs; sends throttled snapshots.</summary>
        public void HostTick(double delta)
        {
            if (Role != LuneRole.Host || MatchState == null || MatchState.Phase != Phase.Combat || MatchState.Combat == null)
                return;
            _frameClock += delta;
            if (_frameClock < LuneNet.FrameInterval)
                return;
            _frameClock = 0.0;
            List<NetUnitRecord> spawned = NewUnitRecords();
            if (spawned.Count > 0)
                Broadcast(LuneNet.KUnitsSpawned, spawned);
            _frameSerial += 1;
            float[] frame = UnitFrame();
            float[] hp = BuildingHpArray();
            foreach (KeyValuePair<int, int> pair in SeatPeers)
            {
                if (pair.Value > 1 && Link != null)
                    Link.SendFrame(pair.Value, _frameSerial, MatchState.Combat.Elapsed, frame, hp);
            }
        }

        /// <summary>Host: call after the settlement (phase left COMBAT) so clients follow in the same step.</summary>
        public void HostAfterCombat()
        {
            if (!IsAuthority() || MatchState == null)
                return;
            AnnouncePhase();
            BroadcastState();
        }

        public void HostFinishCombat()
        {
            if (!IsAuthority() || MatchState == null || MatchState.Phase != Phase.Combat)
                return;
            MatchState.FinishCombat();
            HostAfterCombat();
        }

        /// <summary>Host rematch: a new match with the same seats; clients relaunch on setup.</summary>
        public void HostRematch(MatchOptions options)
        {
            if (!IsAuthority())
                return;
            options.HumanSlot = LocalSlot;
            foreach (LobbyEntry entry in Lobby)
                entry.Ready = entry.Bot;
            SetupMatch(options);
            if (Role == LuneRole.Host)
            {
                foreach (KeyValuePair<int, int> pair in SeatPeers)
                {
                    if (pair.Value > 1)
                        SendFullSync(pair.Value, pair.Key);
                }
                BroadcastLobby();
            }
        }

        // ---------------------------------------------------------------- inbound (client → host)
        /// <summary>Testable host entry for a new connection: protocol check, rejoin or first free seat.</summary>
        public int HostHello(int peer, int protocol, string guestName)
        {
            if (protocol != LuneNet.Protocol)
            {
                Refuse(peer, string.Format("Protokoll {0} passt nicht zum Host ({1}). Bitte dieselbe Version nutzen.", protocol, LuneNet.Protocol));
                return -1;
            }
            if (SeatOfPeer(peer) >= 0)
                return SeatOfPeer(peer);
            string clean = (guestName ?? "").Trim();
            if (clean.Length > 24)
                clean = clean.Substring(0, 24);
            if (clean.Length == 0)
                clean = "Gast " + peer;
            int slot = -1;
            int departedSlot;
            bool rejoin = Departed.TryGetValue(clean, out departedSlot) && !SeatPeers.ContainsKey(departedSlot);
            if (rejoin)
            {
                slot = departedSlot;
            }
            else
            {
                // New guests prefer seats nobody may return to; a departed seat is the last resort.
                var free = new List<int>();
                var open = new List<int>();
                for (int candidate = 0; candidate < 6; candidate++)
                {
                    if (SeatPeers.ContainsKey(candidate))
                        continue;
                    free.Add(candidate);
                    if (!Departed.ContainsValue(candidate))
                        open.Add(candidate);
                }
                if (open.Count > 0)
                    slot = open[0];
                else if (free.Count > 0)
                    slot = free[0];
            }
            if (slot < 0)
            {
                Refuse(peer, "Kein freier Sitzplatz.");
                SessionMessage?.Invoke("Kein freier Sitzplatz für " + clean + ".", true);
                return -1;
            }
            Departed.Remove(clean);
            SeatPeer(slot, peer, clean);
            SessionMessage?.Invoke(string.Format("{0} {1} Slot {2}.", clean, rejoin ? "kehrt zurück auf" : "sitzt auf", slot), false);
            return slot;
        }

        /// <summary>Transport entry for a message from a peer.</summary>
        public void OnMessage(int peer, string kind, object payload)
        {
            var parts = payload as object[];
            switch (kind)
            {
                case LuneNet.KHello:
                    if (Role == LuneRole.Host && parts != null && parts.Length >= 2)
                        HostHello(peer, Convert.ToInt32(parts[0]), parts[1] as string ?? "");
                    break;
                case LuneNet.KSubmit:
                    if (IsAuthority() && parts != null && parts.Length >= 2)
                        HostCommand(peer, Convert.ToInt32(parts[0]), parts[1] as Command);
                    break;
                case LuneNet.KReady:
                    if (IsAuthority())
                    {
                        int slot = -1;
                        if (parts != null && parts.Length > 0)
                            slot = Convert.ToInt32(parts[0]);
                        else if (payload is int)
                            slot = (int)payload;
                        if (SeatOfPeer(peer) == slot)
                            HostReady(slot);
                    }
                    break;
                case LuneNet.KRefused:
                    LastError = parts != null && parts.Length > 0 ? parts[0] as string ?? "" : "";
                    SessionMessage?.Invoke(LastError, true);
                    HostLost?.Invoke();
                    break;
                case LuneNet.KFeedback:
                    if (parts != null && parts.Length >= 3)
                        SessionMessage?.Invoke(parts[2] as string ?? "", !Convert.ToBoolean(parts[1]));
                    break;
                case LuneNet.KSetup:
                    if (parts != null && parts.Length >= 3)
                        ApplySetup(parts[0] as MatchOptions, Convert.ToInt32(parts[1]), parts[2] as List<LobbyEntry>);
                    break;
                case LuneNet.KState:
                    ApplyState(payload as NetState);
                    break;
                case LuneNet.KLobby:
                    ApplyLobby(payload as List<LobbyEntry>);
                    break;
                case LuneNet.KCombatBegin:
                    if (parts != null && parts.Length >= 3)
                        ApplyCombatBegin(Convert.ToInt32(parts[0]), parts[1] as List<NetUnitRecord>, parts[2] as float[]);
                    break;
                case LuneNet.KUnitsSpawned:
                    if (MatchState != null && MatchState.Combat != null && MatchState.Phase == Phase.Combat)
                        AddMirrorUnits(payload as List<NetUnitRecord>);
                    break;
            }
        }

        /// <summary>Transport entry for an unreliable combat frame.</summary>
        public void OnFrame(int peer, int serial, double elapsed, float[] units, float[] buildingHp)
        {
            if (Role != LuneRole.Client)
                return;
            ApplyFrame(serial, elapsed, units, buildingHp);
        }

        void Refuse(int peer, string reason)
        {
            if (Role == LuneRole.Host)
                Link?.Send(peer, LuneNet.KRefused, new object[] { reason });
        }

        // ---------------------------------------------------------------- inbound (host → client)
        public void ApplySetup(MatchOptions options, int seat, List<LobbyEntry> roster)
        {
            LocalSlot = seat;
            Lobby.Clear();
            SeatPeers.Clear();
            if (roster != null)
            {
                foreach (LobbyEntry entry in roster)
                {
                    Lobby.Add(entry.Clone());
                    if (!entry.Bot)
                        SeatPeers[entry.Slot] = entry.Peer;
                }
            }
            options.HumanSlot = seat;
            SetupMatch(options);
            Connected = true;
            LobbyChanged?.Invoke();
        }

        /// <summary>
        /// Client: applies the host's public state. The combat phase itself only starts with
        /// combat_begin, so a state message can never bind views to a stale combat.
        /// </summary>
        public void ApplyState(NetState state)
        {
            if (MatchState == null || state == null)
                return;
            Phase previous = MatchState.Phase;
            MatchState.RoundNumber = state.Round;
            MatchState.Winner = state.Winner;
            MatchState.EndNote = state.EndNote;
            MatchState.BuildingHp.Clear();
            foreach (KeyValuePair<string, double> pair in state.BuildingHp)
                MatchState.BuildingHp[pair.Key] = pair.Value;
            CopyBoss(state.Boss);
            MatchState.LastSettlement = state.LastSettlement;
            foreach (NetPlayerRow row in state.Players)
            {
                int slot = row.Slot;
                if (slot < 0 || slot >= MatchState.Players.Count)
                    continue;
                Player player = MatchState.Players[slot];
                player.Name = slot == LocalSlot ? "Du" : row.Name;
                player.IsHuman = row.IsHuman;
                player.Gold = row.Gold;
                player.Ready = row.Ready;
                player.Earned = row.Earned;
                player.IncomeBonus = row.IncomeBonus;
                player.Spent = row.Spent;
                player.NextSeq = row.NextSeq;
                player.Roster = new List<RosterEntry>();
                if (row.Roster != null)
                {
                    foreach (RosterEntry entry in row.Roster)
                        player.Roster.Add(entry.Clone());
                }
                player.Hero = row.Hero != null ? row.Hero.Clone() : null;
                player.Bookings = new List<Booking>();
                if (row.Bookings != null)
                {
                    foreach (Booking booking in row.Bookings)
                        player.Bookings.Add(booking.Clone());
                }
                // Only the own seat receives its private draft; the others show committed state.
                player.Draft = row.Draft != null ? row.Draft.Clone() : MatchState.Snapshot(player);
                player.Undo = new List<Draft>();
                for (int i = 0; i < row.Undo; i++)
                    player.Undo.Add(null);
            }
            Phase phase = state.Phase;
            if (phase != Phase.Combat)
            {
                if (MatchState.Combat != null)
                {
                    MatchState.Combat.DestroyedCores.Clear();
                    MatchState.Combat.DestroyedCores.AddRange(state.DestroyedCores);
                }
                MatchState.Phase = phase;
            }
            foreach (LobbyEntry entry in Lobby)
            {
                if (entry.Slot >= 0 && entry.Slot < MatchState.Players.Count)
                    entry.Ready = MatchState.Players[entry.Slot].Ready;
            }
            StatesReceived += 1;
            if (previous != MatchState.Phase)
                AnnouncePhase();
            StateReceived?.Invoke();
            LobbyChanged?.Invoke();
        }

        void CopyBoss(BossState source)
        {
            if (source == null)
                return;
            MatchState.Boss.NextAvailableRound = source.NextAvailableRound;
            MatchState.Boss.SettledRound = source.SettledRound;
            MatchState.Boss.Claim = source.Claim != null ? source.Claim.Clone() : null;
            if (source.Blessing != null && source.Blessing.Length == 2)
                MatchState.Boss.Blessing = (int[])source.Blessing.Clone();
            if (source.GlyphReady != null && source.GlyphReady.Length == 2)
                MatchState.Boss.GlyphReady = (int[])source.GlyphReady.Clone();
            if (source.CoreLevel != null && source.CoreLevel.Length == 2)
                MatchState.Boss.CoreLevel = (int[])source.CoreLevel.Clone();
        }

        public void ApplyLobby(List<LobbyEntry> entries)
        {
            Lobby.Clear();
            if (entries != null)
            {
                foreach (LobbyEntry entry in entries)
                    Lobby.Add(entry.Clone());
            }
            LobbyChanged?.Invoke();
        }

        /// <summary>Client: builds a display mirror of the host's combat. Rules never run on it.</summary>
        public void ApplyCombatBegin(int roundNumber, List<NetUnitRecord> records, float[] buildingHp)
        {
            if (MatchState == null)
                return;
            var mirror = new LuneCombat(MatchState.Map, MatchState.Balance, roundNumber);
            IReadOnlyList<BuildingDef> buildings = MatchState.Map.Buildings;
            for (int index = 0; index < buildings.Count; index++)
            {
                double hp = buildingHp != null && index < buildingHp.Length ? buildingHp[index] : 0.0;
                if (hp > 0.0)
                    mirror.AddBuilding(buildings[index], hp);
            }
            _mirror.Clear();
            MatchState.Combat = mirror;
            MatchState.RoundNumber = roundNumber;
            AddMirrorUnits(records);
            _lastFrameTime = Now();
            MatchState.Phase = Phase.Combat;
            AnnouncePhase();
        }

        /// <summary>Client interpolation factor between the last two snapshots.</summary>
        public double FrameAlpha()
        {
            double span = LuneNet.FrameInterval;
            double age = Now() - _lastFrameTime;
            if (age < 0.0)
                return 0.0;
            if (age > span)
                return 1.0;
            return age / span;
        }

        /// <summary>Injectable clock for tests; defaults to real time in seconds.</summary>
        public static Func<double> Now = () => DateTime.UtcNow.TimeOfDay.TotalSeconds;

        void ApplyFrame(int serial, double elapsed, float[] data, float[] buildingHp)
        {
            if (MatchState == null || MatchState.Combat == null || MatchState.Phase != Phase.Combat || serial <= _lastFrameSerial)
                return;
            _lastFrameSerial = serial;
            _lastFrameTime = Now();
            FramesReceived += 1;
            LuneCombat combat = MatchState.Combat;
            combat.Elapsed = elapsed;
            if (data != null)
            {
                for (int baseIndex = 0; baseIndex + LuneNet.FrameStride <= data.Length; baseIndex += LuneNet.FrameStride)
                {
                    LuneUnit unit;
                    if (!_mirror.TryGetValue((int)data[baseIndex], out unit) || unit == null)
                        continue;
                    unit.PreviousPosition = unit.Position;
                    unit.Position = new Vec2(data[baseIndex + 1], data[baseIndex + 2]);
                    unit.Facing = data[baseIndex + 3];
                    unit.Hp = data[baseIndex + 4];
                    unit.MaxHp = data[baseIndex + 5];
                    int flags = (int)data[baseIndex + 6];
                    if (unit.Alive && (flags & 1) == 0)
                        unit.DeathTime = elapsed;
                    unit.Alive = (flags & 1) != 0;
                    unit.InRange = (flags & 2) != 0;
                    // H1: leap and ultimate counters ride in the flag bits (8 bits each, compared for change only).
                    unit.LeapSerial = (flags >> 2) & 0xFF;
                    unit.UltimateSerial = (flags >> 10) & 0xFF;
                    unit.AttackProgress = data[baseIndex + 7];
                    unit.HitCount = (int)data[baseIndex + 8];
                    unit.AttackSerial = (int)data[baseIndex + 9];
                    unit.AbilitySerial = (int)data[baseIndex + 10];
                    unit.HitFlash = data[baseIndex + 11];
                    unit.Shield = data[baseIndex + 12];
                }
            }
            if (buildingHp != null)
            {
                IReadOnlyList<BuildingDef> buildings = MatchState.Map.Buildings;
                int count = Math.Min(buildingHp.Length, buildings.Count);
                for (int index = 0; index < count; index++)
                {
                    LuneUnit building;
                    if (!combat.Buildings.TryGetValue(buildings[index].Id, out building))
                        continue;
                    building.Hp = buildingHp[index];
                    building.Alive = building.Hp > 0.0;
                }
            }
        }

        void AddMirrorUnits(List<NetUnitRecord> records)
        {
            if (records == null || MatchState == null || MatchState.Combat == null)
                return;
            foreach (NetUnitRecord record in records)
            {
                if (_mirror.ContainsKey(record.Id))
                    continue;
                var unit = new LuneUnit();
                unit.Id = record.Id;
                unit.Kind = record.Kind;
                unit.Team = record.Team;
                unit.TeamIndex = record.TeamIndex;
                unit.OwnerSlot = record.OwnerSlot;
                unit.PersistentUid = record.Uid;
                unit.Lane = record.Lane;
                unit.Zone = record.Zone;
                unit.Def = record.Def ?? new UnitDef();
                unit.Position = new Vec2(record.X, record.Y);
                unit.PreviousPosition = unit.Position;
                unit.Facing = record.Facing;
                unit.Hp = record.Hp;
                unit.MaxHp = record.MaxHp;
                unit.Alive = record.Alive;
                MatchState.Combat.Units.Add(unit);
                _mirror[record.Id] = unit;
            }
        }

        // ---------------------------------------------------------------- host serialisation
        List<NetUnitRecord> NewUnitRecords()
        {
            var records = new List<NetUnitRecord>();
            int highest = _sentUnitId;
            foreach (LuneUnit unit in MatchState.Combat.Units)
            {
                if (!unit.IsMobile() || unit.Id <= _sentUnitId)
                    continue;
                if (unit.Id > highest)
                    highest = unit.Id;
                records.Add(UnitRecord(unit));
            }
            _sentUnitId = highest;
            return records;
        }

        /// <summary>Every mobile unit (full sync on join or rejoin mid-combat).</summary>
        public List<NetUnitRecord> AllUnitRecords()
        {
            var records = new List<NetUnitRecord>();
            if (MatchState == null || MatchState.Combat == null)
                return records;
            foreach (LuneUnit unit in MatchState.Combat.Units)
            {
                if (unit.IsMobile())
                    records.Add(UnitRecord(unit));
            }
            return records;
        }

        static NetUnitRecord UnitRecord(LuneUnit unit)
        {
            return new NetUnitRecord
            {
                Id = unit.Id, Kind = unit.Kind, Team = unit.Team, TeamIndex = unit.TeamIndex, OwnerSlot = unit.OwnerSlot,
                Uid = unit.PersistentUid, Lane = unit.Lane, Zone = unit.Zone,
                Def = unit.Def != null ? unit.Def.Clone() : new UnitDef(),
                X = unit.Position.X, Y = unit.Position.Y, Facing = unit.Facing,
                Hp = unit.Hp, MaxHp = unit.MaxHp, Alive = unit.Alive
            };
        }

        public float[] UnitFrame()
        {
            var data = new List<float>();
            foreach (LuneUnit unit in MatchState.Combat.Units)
            {
                if (!unit.IsMobile())
                    continue;
                int flags = (unit.Alive ? 1 : 0) | (unit.InRange ? 2 : 0) | ((unit.LeapSerial & 0xFF) << 2) | ((unit.UltimateSerial & 0xFF) << 10);
                data.Add(unit.Id);
                data.Add((float)unit.Position.X);
                data.Add((float)unit.Position.Y);
                data.Add((float)unit.Facing);
                data.Add((float)unit.Hp);
                data.Add((float)unit.MaxHp);
                data.Add(flags);
                data.Add((float)unit.AttackProgress);
                data.Add(unit.HitCount);
                data.Add(unit.AttackSerial);
                data.Add(unit.AbilitySerial);
                data.Add((float)unit.HitFlash);
                data.Add((float)unit.Shield);
            }
            return data.ToArray();
        }

        public float[] BuildingHpArray()
        {
            IReadOnlyList<BuildingDef> buildings = MatchState.Map.Buildings;
            var data = new float[buildings.Count];
            for (int index = 0; index < buildings.Count; index++)
            {
                double hp;
                if (!MatchState.BuildingHp.TryGetValue(buildings[index].Id, out hp))
                    hp = 0.0;
                if (MatchState.Phase == Phase.Combat && MatchState.Combat != null)
                {
                    LuneUnit building;
                    if (MatchState.Combat.Buildings.TryGetValue(buildings[index].Id, out building))
                        hp = building.Alive ? building.Hp : 0.0;
                }
                data[index] = (float)hp;
            }
            return data;
        }

        /// <summary>Public state for one seat: every committed value, plus the private draft of that seat only.</summary>
        public NetState StateFor(int slot)
        {
            var state = new NetState
            {
                Phase = MatchState.Phase,
                Round = MatchState.RoundNumber,
                Winner = MatchState.Winner,
                EndNote = MatchState.EndNote,
                LastSettlement = MatchState.LastSettlement,
            };
            foreach (KeyValuePair<string, double> pair in MatchState.BuildingHp)
                state.BuildingHp[pair.Key] = pair.Value;
            state.Boss = new BossState
            {
                NextAvailableRound = MatchState.Boss.NextAvailableRound,
                SettledRound = MatchState.Boss.SettledRound,
                Claim = MatchState.Boss.Claim != null ? MatchState.Boss.Claim.Clone() : null,
                Blessing = (int[])MatchState.Boss.Blessing.Clone(),
                GlyphReady = (int[])MatchState.Boss.GlyphReady.Clone(),
                CoreLevel = (int[])MatchState.Boss.CoreLevel.Clone()
            };
            if (MatchState.Combat != null)
                state.DestroyedCores.AddRange(MatchState.Combat.DestroyedCores);
            foreach (Player player in MatchState.Players)
            {
                int seat = player.Slot;
                var row = new NetPlayerRow
                {
                    Slot = seat,
                    Name = SeatPeers.ContainsKey(seat) ? LobbyName(seat, player.Name) : player.Name,
                    IsHuman = player.IsHuman,
                    Gold = player.Gold,
                    Ready = player.Ready,
                    Earned = player.Earned,
                    IncomeBonus = player.IncomeBonus,
                    Spent = player.Spent,
                    NextSeq = player.NextSeq,
                    Hero = player.Hero != null ? player.Hero.Clone() : null,
                };
                foreach (RosterEntry entry in player.Roster)
                    row.Roster.Add(entry.Clone());
                foreach (Booking booking in player.Bookings)
                    row.Bookings.Add(booking.Clone());
                if (seat == slot)
                {
                    row.Draft = player.Draft != null ? player.Draft.Clone() : null;
                    row.Undo = player.Undo.Count;
                }
                state.Players.Add(row);
            }
            return state;
        }

        void BroadcastLobby()
        {
            if (Role == LuneRole.Host)
                Broadcast(LuneNet.KLobby, Lobby);
        }

        void BroadcastState()
        {
            if (Role != LuneRole.Host || MatchState == null || Link == null)
                return;
            foreach (KeyValuePair<int, int> pair in SeatPeers)
            {
                if (pair.Value > 1)
                    Link.Send(pair.Value, LuneNet.KState, StateFor(pair.Key));
            }
        }

        void Broadcast(string kind, object payload)
        {
            if (Link == null)
                return;
            foreach (KeyValuePair<int, int> pair in SeatPeers)
            {
                if (pair.Value > 1)
                    Link.Send(pair.Value, kind, payload);
            }
        }

        void SendFullSync(int peer, int slot)
        {
            if (Link == null)
                return;
            Link.Send(peer, LuneNet.KSetup, new object[] { PublicOptions(), slot, Lobby });
            Link.Send(peer, LuneNet.KState, StateFor(slot));
            if (MatchState.Phase == Phase.Combat && MatchState.Combat != null)
                Link.Send(peer, LuneNet.KCombatBegin, new object[] { MatchState.RoundNumber, AllUnitRecords(), BuildingHpArray() });
        }

        MatchOptions PublicOptions()
        {
            var options = new MatchOptions { Seed = MatchState != null ? MatchState.SeedValue : 1, HumanSlot = LocalSlot, Extended = MatchState != null && MatchState.Extended };
            if (MatchState != null)
            {
                foreach (Player player in MatchState.Players)
                    options.Bunds.Add(player.Bund);
            }
            return options;
        }

        // ---------------------------------------------------------------- lobby / disconnect
        public void SeatPeer(int slot, int peer, string seatName)
        {
            if (!IsAuthority() || slot < 0 || slot > 5)
                return;
            // One peer one seat; a seat held by another peer is never taken over.
            int taken = SeatOfPeer(peer);
            if (taken >= 0 && taken != slot)
                return;
            int current;
            if (SeatPeers.TryGetValue(slot, out current) && current != peer)
                return;
            SeatPeers[slot] = peer;
            bool found = false;
            foreach (LobbyEntry entry in Lobby)
            {
                if (entry.Slot == slot)
                {
                    entry.Peer = peer;
                    entry.Name = seatName;
                    entry.Bot = false;
                    entry.Ready = false;
                    found = true;
                }
            }
            if (!found)
                Lobby.Add(new LobbyEntry { Peer = peer, Slot = slot, Name = seatName, Ready = false, Bot = false });
            if (MatchState != null)
            {
                Player player = MatchState.Players[slot];
                player.IsHuman = true;
                player.Name = seatName;
                // A seat taken during planning drops the bot's uncommitted draft: the gold is the human's.
                if (MatchState.Phase == Phase.Planning)
                {
                    player.Draft = MatchState.Snapshot(player);
                    player.Undo = new List<Draft>();
                    player.Ready = false;
                }
            }
            if (Role == LuneRole.Host && peer > 1)
            {
                SendFullSync(peer, slot);
                BroadcastLobby();
                BroadcastState();
            }
            LobbyChanged?.Invoke();
        }

        /// <summary>Transport entry when a peer goes away: the seat becomes a bot, never a core loss.</summary>
        public void OnPeerDisconnected(int peer)
        {
            if (!IsAuthority())
                return;
            int slot = SeatOfPeer(peer);
            if (slot < 0)
                return;
            SeatPeers.Remove(slot);
            string goneName = DisplayNameFor(slot);
            Departed[goneName] = slot;
            foreach (LobbyEntry entry in Lobby)
            {
                if (entry.Slot == slot)
                {
                    entry.Bot = true;
                    entry.Peer = 0;
                    entry.Ready = true;
                }
            }
            SessionMessage?.Invoke(goneName + " hat die Verbindung getrennt – Slot wird vom Bot übernommen.", false);
            if (MatchState != null)
            {
                MatchState.Players[slot].IsHuman = false;
                if (MatchState.Phase == Phase.Planning && IsAuthority())
                    PlanBot(slot);
            }
            BroadcastLobby();
            if (MatchState != null && MatchState.Phase == Phase.Planning && MatchState.AllReady())
                HostBeginCombat();
            else
                BroadcastState();
        }

        /// <summary>
        /// Public, committed state; host and guest must agree on it after every settlement
        /// (checksum of tools/luneraria/net_pair.gd).
        /// </summary>
        public static string Checksum(LuneMatch match)
        {
            var parts = new List<string>();
            foreach (Player player in match.Players)
            {
                HeroState hero = player.Hero;
                parts.Add(string.Format("{0}:{1}:{2}:{3}", player.Slot, player.Gold, player.Roster.Count, hero == null ? 0 : hero.Xp));
            }
            var ids = new List<string>(match.BuildingHp.Keys);
            ids.Sort(StringComparer.Ordinal);
            foreach (string id in ids)
                parts.Add(string.Format("{0}={1:0.0}", id, match.BuildingHp[id]));
            parts.Add("boss=" + match.Boss.NextAvailableRound);
            parts.Add("winner=" + match.Winner);
            return StableHash(string.Join("|", parts));
        }

        /// <summary>Godot's hash() is process-random; this port uses a stable FNV-1a hex digest.</summary>
        public static string StableHash(string text)
        {
            unchecked
            {
                uint hash = 2166136261;
                for (int i = 0; i < text.Length; i++)
                {
                    hash ^= text[i];
                    hash *= 16777619;
                }
                return hash.ToString("X8");
            }
        }
    }
}