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

namespace ProjectM.Server
{
    /// <summary>
    /// Server-only, one-shot spawner for the GLOBAL cycle-director ghost (mirrors SharedStorageSpawnSystem,
    /// but MINUS the RegionTag — the director must stay global so GhostRelevancy keeps it relevant to every
    /// region). On its first update it reads the baked <see cref="CycleDirectorSpawner"/> + NetworkTime,
    /// instantiates the ghost, initializes <see cref="CycleState"/> (Expedition, cycle 1, PhaseEndTick =
    /// now + <see cref="CyclePhase.ExpeditionTicks"/>), adds the server-only <see cref="CycleRuntime"/>, and
    /// places it at the base center (preserving the prefab's baked LocalTransform scale — FromPosition would
    /// reset the replicated Scale GhostField), then destroys the spawner so it idles.
    /// </summary>
    [BurstCompile]
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    public partial struct CycleDirectorSpawnSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<CycleDirectorSpawner>();
            state.RequireForUpdate<NetworkTime>();
        }

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

            var spawnerEntity = SystemAPI.GetSingletonEntity<CycleDirectorSpawner>();
            var spawner = SystemAPI.GetComponent<CycleDirectorSpawner>(spawnerEntity);

            var ecb = new EntityCommandBuffer(Allocator.Temp);

            if (spawner.Prefab != Entity.Null)
            {
                var director = ecb.Instantiate(spawner.Prefab);

                // Place at the base center, preserving the prefab's baked scale/rotation.
                var xform = SystemAPI.GetComponent<LocalTransform>(spawner.Prefab);
                if (SystemAPI.TryGetSingleton<BaseAnchor>(out var anchor))
                    xform.Position = BaseGridMath.PlotCenter(anchor);
                ecb.SetComponent(director, xform);

                // Override the baked CycleState with the real start tick; add server-only bookkeeping.
                ecb.SetComponent(director, new CycleState
                {
                    Phase = CyclePhase.Expedition,
                    CycleNumber = 1,
                    PhaseEndTick = TickUtil.NonZero(now + CyclePhase.ExpeditionTicks),
                });
                ecb.AddComponent(director, new CycleRuntime { DefendStartWave = 0 });
            }

            // One-shot: remove the spawner so RequireForUpdate fails and the system idles.
            ecb.DestroyEntity(spawnerEntity);

            ecb.Playback(state.EntityManager);
        }
    }
}