using System;
using System.Collections.Generic;
using System.Linq;

namespace Luneraria.Core.Tests
{
    /// <summary>
    /// Multi-round loopback with two sessions (port of tools/luneraria/net_rounds.py, 12 checks).
    /// Host and guest play five rounds through the real LuneSession; after every settlement the
    /// public checksums must agree. Guest A leaves during the combat of round 2, the bot takes
    /// over, guest B returns with the same display name and must get the same seat back. The
    /// guest never runs a combat step and receives host snapshots. This is a local in-process
    /// loopback, not a six-player internet match.
    /// </summary>
    public sealed class NetRoundsSuite : CheckSuite
    {
        public override string Name { get { return "net_rounds"; } }

        const int Rounds = 5;
        const int DropRound = 2;
        /// <summary>Host combat steps per tick (net_pair.gd steps_per_frame); snapshots still flow.</summary>
        const int StepsPerTick = 8;

        sealed class CombatLog
        {
            public int Round;
            public int Frames;
            public int LocalSteps;
        }

        readonly Dictionary<int, string> _hostSums = new Dictionary<int, string>();
        readonly Dictionary<int, string> _guestSums = new Dictionary<int, string>();
        readonly List<CombatLog> _combats = new List<CombatLog>();
        readonly List<int> _seatsA = new List<int>();
        readonly List<int> _seatsB = new List<int>();
        readonly List<string> _hostMessages = new List<string>();
        readonly List<string> _errors = new List<string>();

        protected override void RunChecks()
        {
            var hub = new LuneLoopback();
            LuneSession host = hub.Attach(1, new LuneSession());
            host.SessionMessage += (text, isError) =>
            {
                if (isError)
                    _errors.Add("host: " + text);
                else
                    _hostMessages.Add(text);
            };
            var options = new MatchOptions
            {
                Seed = 42,
                HumanSlot = 0,
                Bunds = new List<string> { "glutpakt", "wurzelbund", "glutpakt", "wurzelbund", "glutpakt", "wurzelbund" }
            };
            if (!host.HostNetwork(options, "Host"))
            {
                Check(false, "host starts: " + host.LastError);
                return;
            }

            const int peerA = 10;
            const int peerB = 11;
            LuneSession guest = Join(hub, peerA, "Gast", _seatsA, _errors);
            bool spoofRejected = !guest.HostCommand(1, 5, Command.Buy("w01")).Ok;
            bool dropped = false;
            int hostPlannedRound = 0;
            int guestPlannedRound = 0;
            int framesAtSegment = 0;
            var current = new CombatLog();

            for (int guard = 0; guard < 8000 && host.MatchState.Phase != Phase.Over && host.MatchState.RoundNumber <= Rounds + 1; guard++)
            {
                LuneMatch match = host.MatchState;
                if (match.Phase == Phase.Planning)
                {
                    if (match.RoundNumber > Rounds)
                        break;
                    host.PlanBotSeats();
                    PlanOnce(host, ref hostPlannedRound, host.LocalSlot, true);
                    if (guest != null && guest.MatchState != null && guest.LocalSlot >= 0)
                        PlanOnce(guest, ref guestPlannedRound, guest.LocalSlot, false);
                }
                else if (match.Phase == Phase.Combat)
                {
                    if (current.Round != match.RoundNumber)
                    {
                        current = new CombatLog { Round = match.RoundNumber };
                        _combats.Add(current);
                        framesAtSegment = guest != null ? guest.FramesReceived : 0;
                    }
                    for (int step = 0; step < StepsPerTick && match.Phase == Phase.Combat; step++)
                        match.StepCombat();
                    host.HostTick(LuneNet.FrameInterval);
                    if (guest != null && guest.MatchState != null && guest.MatchState.Combat != null)
                    {
                        current.Frames = Math.Max(current.Frames, guest.FramesReceived - framesAtSegment);
                        current.LocalSteps = Math.Max(current.LocalSteps, guest.MatchState.Combat.Steps);
                    }
                    // Leave on a snapshot of the combat of DropRound: short combats may send only a few.
                    if (!dropped && hub.Has(peerA) && match.RoundNumber == DropRound && current.Frames > 0)
                    {
                        if (guest != null)
                            current.Frames = Math.Max(current.Frames, guest.FramesReceived - framesAtSegment);
                        dropped = true;
                        hub.Detach(peerA);
                        // Guest B returns with the same display name while the seat is bot-held.
                        guest = Join(hub, peerB, "Gast", _seatsB, _errors);
                        guestPlannedRound = 0;
                        framesAtSegment = guest.FramesReceived;
                    }
                }

                // Settlement: the phase left combat in this or a previous step.
                if (current.Round != 0 && match.Phase != Phase.Combat)
                {
                    if (guest != null && guest.MatchState != null && guest.MatchState.Combat != null)
                    {
                        current.Frames = Math.Max(current.Frames, guest.FramesReceived - framesAtSegment);
                        current.LocalSteps = Math.Max(current.LocalSteps, guest.MatchState.Combat.Steps);
                    }
                    host.HostAfterCombat();
                    NoteSums(host, guest, current.Round);
                    current = new CombatLog();
                }
            }
            if (current.Round != 0)
            {
                host.HostAfterCombat();
                NoteSums(host, guest, current.Round);
            }

            // ---------------------------------------------------------------- 12 checks
            List<int> compared = _hostSums.Keys.Where(r => _guestSums.ContainsKey(r)).OrderBy(r => r).ToList();
            List<int> mismatches = compared.Where(r => _hostSums[r] != _guestSums[r]).ToList();
            Check(host.MatchState != null, "host_ok");
            Check(dropped, "guest_a_ok (left during the combat)");
            Check(_seatsB.Count > 0, "guest_b_ok");
            Check(spoofRejected, "spoof_rejected");
            Check(compared.Count >= Rounds - 1, "rounds_compared " + compared.Count + " of " + Rounds + " (" + string.Join(",", compared) + ")");
            Check(mismatches.Count == 0 && compared.Count > 0, "checksums_equal " + string.Join(",", mismatches));
            Check(_combats.Count > 0 && _combats.All(c => c.LocalSteps == 0), "client_never_simulates " + string.Join(",", _combats.Select(c => c.Round + ":" + c.LocalSteps)));
            Check(_combats.Count > 0 && _combats.All(c => c.Frames > 0), "client_receives_frames " + string.Join(",", _combats.Select(c => c.Round + ":" + c.Frames)));
            Check(_seatsA.Count > 0 && _seatsB.Count > 0 && _seatsB[0] == _seatsA[0], "rejoin_same_seat a=" + string.Join(",", _seatsA) + " b=" + string.Join(",", _seatsB));
            Check(_hostMessages.Any(m => m.Contains("Slot wird vom Bot übernommen")), "bot_took_over");
            Check(_hostMessages.Any(m => m.Contains("kehrt zurück auf")), "rejoin_announced");
            Check(_errors.Count == 0, "no_script_errors " + string.Join(";", _errors));
        }

        static LuneSession Join(LuneLoopback hub, int peer, string name, List<int> seats, List<string> errors)
        {
            LuneSession guest = hub.Attach(peer, new LuneSession());
            guest.SessionMessage += (text, isError) =>
            {
                if (isError)
                    errors.Add("guest " + peer + ": " + text);
            };
            guest.MatchResetup += () => seats.Add(guest.LocalSlot);
            guest.JoinNetwork(name);
            guest.OnClientConnected();
            return guest;
        }

        static void PlanOnce(LuneSession session, ref int plannedRound, int slot, bool waitForPeer)
        {
            LuneMatch match = session.MatchState;
            if (slot < 0 || plannedRound == match.RoundNumber || match.Players[slot].Ready)
                return;
            // The host waits for a seated guest in every planning phase (covers the rejoin case).
            if (waitForPeer && session.SeatPeers.Count < 2)
                return;
            plannedRound = match.RoundNumber;
            List<string> ids = match.BaseIds(match.Players[slot].Bund);
            int gold = match.GoldOf(slot);
            List<string> affordable = ids.Where(id => DataCatalog.GetUnit(id).Cost <= gold).ToList();
            if (affordable.Count > 0)
                session.Submit(Command.Buy(affordable[match.RoundNumber % affordable.Count]));
            session.ReadyUp();
        }

        void NoteSums(LuneSession host, LuneSession guest, int fought)
        {
            if (fought < 1 || host.MatchState == null)
                return;
            _hostSums[fought] = LuneSession.Checksum(host.MatchState);
            if (guest != null && guest.MatchState != null)
                _guestSums[fought] = LuneSession.Checksum(guest.MatchState);
        }
    }
}