using System;
using Luneraria.Core;

namespace Luneraria.View
{
    /// <summary>
    /// Runs a match on the host (U2C/U2D, human seat since U3) against wall-clock time: planning
    /// (the bots plan through the command interface), combat in fixed steps, a pause after the
    /// settlement, the next round, until an Ancient falls. Only the core decides; time only paces
    /// the calls, so a bot match calls the core in the order of LuneTrace.RunCore at every frame
    /// rate. With a human seat (HumanSlot &gt;= 0) the bots plan the other five seats and planning
    /// waits for the human's Ready, as offline in Godot (lune_game.gd); there is no pause after
    /// the settlement.
    /// </summary>
    public sealed class LuneMatchRunner
    {
        public enum Stage { Planning, Combat, Settled, Over }

        public readonly LuneMatch Match;
        public readonly LuneClock Clock;
        public readonly string Profile;
        /// <summary>The seat a human plans through the HUD; -1 for a bot match.</summary>
        public readonly int HumanSlot;
        public LuneTrace Trace;
        public double PlanningSeconds = 1.0;
        public double SettledSeconds = 2.0;
        public int MaxRound = 60;
        public Stage Current { get; private set; }
        public int StepsThisFrame { get; private set; }

        public event Action<LuneCombat> CombatStarted;
        public event Action<Settlement> Settled;
        public event Action<int> Finished;

        double _stageTime;

        public LuneMatchRunner(MatchOptions options, int startRound = 1, int extraGold = 0, string profile = "")
        {
            Match = NewMatch(options, startRound, extraGold);
            Clock = new LuneClock(Match.Balance.SimStep);
            Profile = profile;
            HumanSlot = options.HumanSlot >= 0 && options.HumanSlot < 6 ? options.HumanSlot : -1;
            if (HumanSlot >= 0)
                SettledSeconds = 0.0;
            EnterPlanning();
        }

        /// <summary>Adopts an existing match (U4 network session: the host owns it, the guest mirrors it).</summary>
        public LuneMatchRunner(LuneMatch match, int humanSlot, LuneSession session = null)
        {
            Match = match;
            Clock = new LuneClock(Match.Balance.SimStep);
            Profile = "";
            Session = session;
            HumanSlot = humanSlot >= 0 && humanSlot < 6 ? humanSlot : -1;
            if (HumanSlot >= 0)
                SettledSeconds = 0.0;
            Current = match.Phase == Phase.Combat ? Stage.Combat : match.Phase == Phase.Over ? Stage.Over : Stage.Planning;
            _stageTime = 0.0;
        }

        /// <summary>A match with the public fixtures the golden scenarios use (start round, gold).</summary>
        public static LuneMatch NewMatch(MatchOptions options, int startRound, int extraGold)
        {
            var match = new LuneMatch();
            match.Setup(options);
            if (startRound > 1)
                match.RoundNumber = startRound;
            if (extraGold != 0)
                foreach (Player player in match.Players)
                    player.Draft.Gold += extraGold;
            return match;
        }

        void EnterPlanning()
        {
            Current = Stage.Planning;
            _stageTime = 0.0;
            if (Session != null)
                return;
            for (int slot = 0; slot < 6; slot++)
            {
                if (slot != HumanSlot)
                    LuneBot.Plan(Match, slot, Profile);
            }
        }

        /// <summary>Bound network session (U4); when set, the session owns planning and combat start.</summary>
        public LuneSession Session;

        /// <summary>Advances by simulated seconds (frame time times match speed).</summary>
        public void Advance(double seconds)
        {
            StepsThisFrame = 0;
            switch (Current)
            {
                case Stage.Planning:
                    _stageTime += seconds;
                    // A bot match starts after a short look at the plans; a human starts it with Ready.
                    // With a session the host already began the combat when every seat was ready.
                    if (Session != null)
                    {
                        if (Match.Phase == Phase.Combat)
                            StartCombat();
                    }
                    else if (HumanSlot < 0 ? _stageTime >= PlanningSeconds : Match.AllReady())
                        StartCombat();
                    break;
                case Stage.Combat:
                    StepsThisFrame = Clock.Advance(seconds, StepOnce);
                    if (Match.Phase != Phase.Combat)
                        EndCombat();
                    break;
                case Stage.Settled:
                    _stageTime += seconds;
                    if (_stageTime >= SettledSeconds)
                        EnterPlanning();
                    break;
            }
        }

        /// <summary>
        /// The human's Ready (Godot _on_ready): the plan becomes binding; once every seat is ready
        /// the combat starts at once.
        /// </summary>
        public bool Ready()
        {
            if (Current != Stage.Planning || HumanSlot < 0 || Match.Phase != Phase.Planning)
                return false;
            Match.SetReady(HumanSlot);
            if (Match.AllReady())
                StartCombat();
            return true;
        }

        void StartCombat()
        {
            if (Match.Phase != Phase.Combat)
                Match.BeginCombat();
            Clock.Reset();
            Current = Stage.Combat;
            CombatStarted?.Invoke(Match.Combat);
        }

        bool StepOnce()
        {
            Match.StepCombat();
            Trace?.RecordStep(Match.Combat);
            return Match.Phase == Phase.Combat;
        }

        void EndCombat()
        {
            Trace?.RecordSettlement(Match);
            Settled?.Invoke(Match.LastSettlement);
            _stageTime = 0.0;
            if (Match.Phase == Phase.Over || Match.RoundNumber > MaxRound)
            {
                Current = Stage.Over;
                Finished?.Invoke(Match.Winner);
            }
            else
            {
                Current = Stage.Settled;
            }
        }
    }
}