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;

            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);

                // Boot the run-state in Calm (the persistent default) — no timer; ThreatDirector arms sieges.
                ecb.SetComponent(director, new CycleState
                {
                    Phase = CyclePhase.Calm,
                    CycleNumber = 1,
                    PhaseEndTick = 0u,
                });
                ecb.AddComponent(director, new CycleRuntime { DefendStartWave = 0 });
                ecb.AddComponent(director, new ThreatState());

                // Born-correct load: if the menu staged a save (Continue), apply it AT SPAWN so the director
                // ghost never serializes a default GoalProgress / empty ledger to clients (no replication flicker).
                if (SystemAPI.TryGetSingletonEntity<PendingSave>(out var pendingEntity))
                {
                    var pending = SystemAPI.GetComponent<PendingSave>(pendingEntity);
                    if (pending.HasData != 0)
                    {
                        ecb.SetComponent(director, new GoalProgress { Charge = pending.GoalCharge, Target = pending.GoalTarget });
                        var srcLedger = SystemAPI.GetBuffer<PendingSaveLedgerRow>(pendingEntity);
                        var destLedger = ecb.SetBuffer<StorageEntry>(director);
                        SaveApply.WriteLedger(srcLedger, destLedger);
                    }
                    ecb.DestroyEntity(pendingEntity);
                }

                // Host-only autosave flag; SaveWriteSystem consumes it on the Siege->Calm checkpoint.
                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);
        }
    }
}