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 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
    /// — the shared-ledger / RunInfo / meta host (its old cycle/siege/goal/core state is retired, LANTERN purge) —
    /// applies a menu-staged save born-correct, 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;

            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);

                // Born-correct load: if the menu staged a save (Continue), apply the ledger AT SPAWN so the
                // director ghost never serializes an empty ledger to clients (no replication flicker).
                //
                // 2026-08-07 audit purge: this block also seeded RunRuntime (HostSalt), RouteCommand,
                // PortalCommand, MetaCounters, MetaTierState and a born-correct RunInfo mirror. All of that was
                // the superseded base/expedition run-FSM and meta shop; the director now hosts exactly one thing
                // — the global resource ledger.
                bool restoredLedger = false;
                if (SystemAPI.TryGetSingletonEntity<PendingSave>(out var pendingEntity))
                {
                    var pending = SystemAPI.GetComponent<PendingSave>(pendingEntity);
                    if (pending.HasData != 0)
                    {
                        var srcLedger = SystemAPI.GetBuffer<PendingSaveLedgerRow>(pendingEntity);
                        var destLedger = ecb.SetBuffer<StorageEntry>(director);
                        SaveApply.WriteLedger(srcLedger, destLedger);
                        restoredLedger = true; // a save restored the ledger -> do NOT seed starting Ore
                    }
                    ecb.DestroyEntity(pendingEntity);
                }

                // DR-042 C6c: NEW game only (no restored ledger) -> seed a little Ore so the build loop isn't a
                // cold start with nothing to place. Appended BEFORE Playback so the ghost first-serializes WITH
                // the seed (no empty-ledger replication flicker).
                if (!restoredLedger)
                    ecb.AppendToBuffer(director, new StorageEntry { ItemId = ResourceId.Ore, Count = Tuning.StartingOre });

                // Host-only autosave flag; SaveWriteSystem consumes it (RunDirectorSystem raises it on bank).
                ecb.AddComponent(director, new SaveRequest { Pending = 0 });
            }

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

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