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());
                // END-2: server-only run-phase marker (Normal until the goal cap arms the final siege). Added at
                // spawn like CycleRuntime/ThreatState (never on the ghost serializer). RunOutcome is baked on the prefab.
                ecb.AddComponent(director, new RunPhase { Value = RunPhaseId.Normal });

                // Born-correct load: if the menu staged a save (Continue), apply it AT SPAWN so the director
                // DR-042 C6c: a NEW game seeds starting Ore below; a restored save (Continue) keeps its ledger.
                bool restoredLedger = false;
                // 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)
                    {
                        // END-2: clamp the restored Target to the baked run-length so a pre-v5 save carrying the old
                        // Target=10 still honours the slice's baked Target=4 (the final siege stays reachable).
                        int bakedTarget = SystemAPI.HasComponent<GoalProgress>(spawner.Prefab)
                            ? SystemAPI.GetComponent<GoalProgress>(spawner.Prefab).Target : pending.GoalTarget;
                        int restoredTarget = pending.GoalTarget > 0 && pending.GoalTarget < bakedTarget
                            ? pending.GoalTarget : bakedTarget;
                        ecb.SetComponent(director, new GoalProgress { Charge = pending.GoalCharge, Target = restoredTarget });
                        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 (C6c)

                        // END-1: born-correct the Engine Core. Max comes from the BAKED prefab (never the save); a
                        // persisted wounded Current (>0) restores clamped to Max, else (0 = pre-v4 save) born full.
                        if (SystemAPI.HasComponent<CoreIntegrity>(spawner.Prefab))
                        {
                            var bakedCore = SystemAPI.GetComponent<CoreIntegrity>(spawner.Prefab);
                            int restoredCore = pending.CoreCurrent > 0
                                ? (pending.CoreCurrent < bakedCore.Max ? pending.CoreCurrent : bakedCore.Max)
                                : bakedCore.Max;
                            ecb.SetComponent(director, new CoreIntegrity { Current = restoredCore, Max = bakedCore.Max, OverrunTick = 0u });
                        }

                        // END-2: born-correct the terminal run outcome (a won/lost run loads finished + halted; a pre-v5
                        // save / New Game = 0 -> InProgress). Independent of the Core -> NOT nested in the CoreIntegrity guard.
                        ecb.SetComponent(director, new RunOutcome { Value = pending.RunOutcome });

                    }
                    ecb.DestroyEntity(pendingEntity);
                }

                // DR-042 C6c: NEW game only (no restored ledger) -> seed a little Ore so the build loop isn't a cold
                // deadlock (a turret needs Charge from a Fabricator that costs Ore you haven't mined yet). 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 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);
        }
    }
}