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

namespace ProjectM.Server
{
    /// <summary>
    /// Server-authoritative handler for <see cref="StorageOpRequest"/> RPCs (deposit/withdraw on the
    /// shared storage container). Resolves the single <see cref="SharedStorageContainer"/> as a singleton,
    /// applies the op to its replicated <see cref="StorageEntry"/> buffer via <see cref="StorageMath"/>,
    /// and destroys the request entity. Runs in the default SimulationSystemGroup (NOT the prediction
    /// loop), so a server event is applied exactly once (no rollback double-apply). Op is read as a byte
    /// (see <see cref="StorageOp"/>); the buffer mutation auto-replicates to all clients via GhostField.
    /// </summary>
    [BurstCompile]
    [WorldSystemFilter(WorldSystemFilterFlags.ServerSimulation)]
    public partial struct StorageOpReceiveSystem : ISystem
    {
        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<SharedStorageContainer>();

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

        [BurstCompile]
        public void OnUpdate(ref SystemState state)
        {
            var containerEntity = SystemAPI.GetSingletonEntity<SharedStorageContainer>();
            var contents = SystemAPI.GetBuffer<StorageEntry>(containerEntity);

            var ecb = new EntityCommandBuffer(Allocator.Temp);

            foreach (var (request, requestEntity) in
                     SystemAPI.Query<RefRO<StorageOpRequest>>().WithAll<ReceiveRpcCommandRequest>().WithEntityAccess())
            {
                var op = request.ValueRO;
                if (op.Op == StorageOp.Withdraw)
                    StorageMath.Withdraw(contents, op.ItemId, op.Count);
                else
                    StorageMath.Deposit(contents, op.ItemId, op.Count);

                ecb.DestroyEntity(requestEntity);
            }

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