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

namespace ProjectM.Server
{
    /// <summary>
    /// Server-authoritative player spawn. On each received <see cref="GoInGameRequest"/>: mark the
    /// source connection in-game, instantiate the player ghost from the baked
    /// <see cref="PlayerSpawner"/>, stamp <see cref="GhostOwner"/> with the connection's
    /// <see cref="NetworkId"/>, place it at the spawn point, and link it to the connection's
    /// LinkedEntityGroup so it auto-despawns on disconnect. Mirrors the netcode "networked-cube"
    /// ModifiedGoInGameServer sample. All structural changes are batched through an
    /// <see cref="EntityCommandBuffer"/>.
    /// </summary>
    [BurstCompile]
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    public partial struct GoInGameServerSystem : ISystem
    {

        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<PlayerSpawner>();

            var builder = new EntityQueryBuilder(Allocator.Temp)
                .WithAll<GoInGameRequest, ReceiveRpcCommandRequest>();
            state.RequireForUpdate(state.GetEntityQuery(builder));
        }

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            // Step 12a availability guard (review N2/L1-6): the born-correct meta seeding below needs the baked
            // catalog + the live director's tier record. Both are per-tick-uniform, so guard ONCE at the TOP,
            // BEFORE the ECB exists — a per-request continue would already have marked the connection in-game.
            // Nothing is consumed; RequireForUpdate re-passes and the request retries next tick (a ≤1-tick window
            // in practice — the director spawns at subscene-stream, before any GoInGame round-trip).
            // GYM (LANTERN A1): a fresh gym subscene has no CycleDirector, so the base meta-catalog guard would
            // block spawns forever. GymTag switches to the clean gym path (no meta seeding; a default Spark socket
            // loadout below instead). The class seeds still apply (harmless: AbilityFireSystem reads sockets).
            bool isGym = SystemAPI.HasSingleton<GymTag>();
            // 2026-08-07 audit purge: spawning used to block until the MetaUpgradeCatalog + MetaTierState buffer
            // were present (the audit's M12 — a missing catalog stranded the GoInGame RPC and no player ever
            // spawned). Both are deleted, so that whole gate and its one-shot warning are gone with them.

            var spawner = SystemAPI.GetSingleton<PlayerSpawner>();

            // M5 home base: re-root the spawn ring on the baked BaseAnchor when present; fall back
            // to the spawner's SpawnPoint if the base subscene hasn't streamed in yet.
            var center = spawner.SpawnPoint;
            if (SystemAPI.TryGetSingleton<BaseAnchor>(out var baseAnchor))
                center = BaseGridMath.PlotCenter(baseAnchor);
            var ecb = new EntityCommandBuffer(Allocator.Temp);

            foreach (var (receive, goReq, requestEntity) in
                     SystemAPI.Query<RefRO<ReceiveRpcCommandRequest>, RefRO<GoInGameRequest>>().WithEntityAccess())
            {
                var connection = receive.ValueRO.SourceConnection;
                ecb.AddComponent<NetworkStreamInGame>(connection);

                var networkId = SystemAPI.GetComponent<NetworkId>(connection);

                var player = ecb.Instantiate(spawner.PlayerPrefab);
                ecb.SetComponent(player, LocalTransform.FromPosition(center + PlayerSpawnMath.SpawnOffset(networkId.Value, spawner.SpawnRingRadius, spawner.RingSlots)));
                ecb.SetComponent(player, new GhostOwner { NetworkId = networkId.Value });
                // Tag the player into the base region (M6 region/relevancy split).
                ecb.AddComponent(player, new RegionTag { Region = RegionId.Base });
                // Slice 2 -> LANTERN: seed the chosen frame on the just-instantiated player. The 4-socket Spark
                // loadout IS the ability model (the legacy single-AbilityRef path is deleted); the DRG-asymmetry
                // traits ride permanent StatModifiers (CharacterStatsRef stays Default -> deltas replicate via the
                // OwnerSendType.All buffer). 0 -> Warrior/Bathynaut.
                byte classId = ClassTraits.Normalize(goReq.ValueRO.ClassId);
                ClassTraits.AppendSeeds(classId, player, ecb);
                // Expedition redesign: the server-only class anchor the meta systems key on (born-correct meta
                // seeding at Step 12a + per-class spend at Step 13 resolve the tier record through this).
                // 2026-08-07 audit purge: PlayerClass was a second, server-only copy of the same byte FrameId
                // already replicates (audit finding M5). It existed so the meta shop could key on it; the meta
                // shop is gone, so FrameId is now the single frame identity.
                ecb.AddComponent(player, new FrameId { Value = classId }); // Add (not Set): baked on the real player; absent on the minimal test prefab // replicated frame/class signal
                // Per-frame default Spark loadout on keys 1-4 (UNCONDITIONAL since the legacy path died — without
                // this a non-gym spawn would have four empty sockets and no abilities at all).
                ClassTraits.FrameLoadout(classId, out byte f0, out byte f1, out byte f2, out byte f3);
                var sockets = ecb.SetBuffer<AbilitySocket>(player);
                sockets.Add(new AbilitySocket { SparkId = f0 });
                sockets.Add(new AbilitySocket { SparkId = f1 });
                sockets.Add(new AbilitySocket { SparkId = f2 });
                sockets.Add(new AbilitySocket { SparkId = f3 });
                // 2026-08-07 audit purge: born-correct PERMANENT meta seeding replayed each frame's persisted
                // upgrade tiers as meta-band StatModifiers. The meta shop is deleted, so a spawn now carries only
                // the frame's own stat band (ClassTraits.AppendSeeds above).

                // Auto-despawn the player when its owning connection is removed.
                ecb.AppendToBuffer(connection, new LinkedEntityGroup { Value = player });

                ecb.DestroyEntity(requestEntity);
            }

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