using ProjectM.Simulation;
using Unity.Burst;
using Unity.Collections;
using Unity.Entities;
using Unity.Mathematics;
using Unity.NetCode;

namespace ProjectM.Server
{
    /// <summary>
    /// Server-only composite ThreatDirector — the data-driven base-attack SCHEDULER. It owns the decision of WHEN
    /// and HOW BIG a siege is; <see cref="CyclePhaseSystem"/> owns the Calm↔Siege transition. The single documented
    /// hand-off is <see cref="ThreatState.PendingSiegeSize"/> (this system sets it; CyclePhaseSystem consumes it).
    /// This slice wires ONE source — POST-EXPEDITION retaliation: a player returning to base (counted as
    /// <see cref="ThreatState.PendingReturns"/> by <see cref="ExpeditionGateSystem"/>) arms a siege of
    /// <see cref="ThreatConfig.SizeBase"/> Husks after a <see cref="ThreatConfig.PostExpeditionDelayTicks"/>
    /// telegraph. The Heat/Schedule sources are reserved (config baked-but-inert) so they drop in additively with
    /// no re-bake. It also enforces a BOUNDED siege lifetime (<see cref="ThreatConfig.SiegeTimeoutTicks"/>): an
    /// unattended siege (e.g. an empty base) auto-collapses so the loop can never soft-lock. Runs in the plain
    /// server SimulationSystemGroup, ordered Gate -> ThreatDirector -> RunState(CyclePhaseSystem) -> Wave so a
    /// return is consumed the same tick. All timing is wrap-safe NetworkTick math (TickUtil.NonZero +
    /// NetworkTick.IsNewerThan / TicksSince), never raw uint.
    /// </summary>
    [BurstCompile]
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    [UpdateInGroup(typeof(SimulationSystemGroup))]
    [UpdateAfter(typeof(ExpeditionGateSystem))]
    [UpdateBefore(typeof(CyclePhaseSystem))]
    public partial struct ThreatDirectorSystem : ISystem
    {
        EntityQuery m_Husks;

        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<NetworkTime>();
            state.RequireForUpdate<CycleState>();
            state.RequireForUpdate<ThreatState>();
            state.RequireForUpdate<ThreatConfig>();
            m_Husks = state.GetEntityQuery(ComponentType.ReadOnly<EnemyTag>());
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            var serverTick = SystemAPI.GetSingleton<NetworkTime>().ServerTick;
            if (!serverTick.IsValid)
                return;
            uint now = serverTick.TickIndexForValidTick;

            var cycleEntity = SystemAPI.GetSingletonEntity<CycleState>();
            var cycle = SystemAPI.GetComponent<CycleState>(cycleEntity);
            var threat = SystemAPI.GetComponent<ThreatState>(cycleEntity);
            var config = SystemAPI.GetComponent<ThreatConfig>(cycleEntity);

            // ---- SOURCE: post-expedition retaliation. A returning player arms ONE siege (simultaneous returns
            // collapse to a single arming — extending the de-dup the gate's one-increment-per-return starts). ----
            if (config.PostExpeditionEnabled != 0 && threat.PendingReturns > 0)
            {
                if (cycle.Phase == CyclePhase.Calm && threat.PendingSiegeSize == 0)
                {
                    int size = config.SizeBase + config.SizePerExpeditionResource * 0; // haul-scaling deferred (field baked)
                    threat.PendingSiegeSize = math.max(1, size);
                    threat.ArmTick = TickUtil.NonZero(now + config.PostExpeditionDelayTicks);
                }
                threat.PendingReturns = 0; // consume regardless so returns can't pile up
            }

            // ---- BOUNDED RESOLUTION: a Siege can't drag forever. Record its start; after SiegeTimeoutTicks cull
            // the remaining Husks + stop spawning so CyclePhaseSystem's DefendCleared returns the base to Calm. ----
            if (cycle.Phase == CyclePhase.Siege)
            {
                if (threat.SiegeStartTick == 0)
                {
                    threat.SiegeStartTick = TickUtil.NonZero(now);
                }
                else if (config.SiegeTimeoutTicks > 0)
                {
                    var start = new NetworkTick(threat.SiegeStartTick);
                    if (start.IsValid && serverTick.TicksSince(start) > (int)config.SiegeTimeoutTicks)
                    {
                        // Collapse the siege: cull every remaining Husk (a cached tag query, never RefRO on a tag).
                        var husks = m_Husks.ToEntityArray(Allocator.Temp);
                        if (husks.Length > 0)
                        {
                            var ecb = new EntityCommandBuffer(Allocator.Temp);
                            for (int i = 0; i < husks.Length; i++)
                                ecb.DestroyEntity(husks[i]);
                            ecb.Playback(state.EntityManager);
                            ecb.Dispose();
                        }
                        husks.Dispose();

                        if (SystemAPI.TryGetSingletonEntity<WaveState>(out var waveEntity))
                        {
                            var w = SystemAPI.GetComponent<WaveState>(waveEntity);
                            w.RemainingToSpawn = 0;
                            SystemAPI.SetComponent(waveEntity, w);
                        }
                        threat.SiegeStartTick = 0;
                    }
                }
            }
            else
            {
                threat.SiegeStartTick = 0; // not under siege
            }

            SystemAPI.SetComponent(cycleEntity, threat);
        }
    }
}