using NUnit.Framework;
using ProjectM.Server;
using ProjectM.Simulation;
using Unity.Core;
using Unity.Entities;
using Unity.NetCode;

namespace ProjectM.Tests
{
    /// <summary>
    /// Plain-Entities EditMode tests for the server-only <see cref="StorageOpReceiveSystem"/> — the RPC handler
    /// that applies deposit/withdraw ops to the shared storage container's replicated <c>StorageEntry</c> buffer.
    /// A bare world with a <c>SharedStorageContainer</c> singleton (carrying the buffer) plus synthetic
    /// <c>StorageOpRequest</c> + <c>ReceiveRpcCommandRequest</c> entities exercises the handler. The system plays
    /// its ECB back immediately (Temp allocator), so the handled request entity is destroyed within the single
    /// group update. Mirrors HealthApplyDamageSystemTests. Locks the deposit/withdraw/drop-row behaviour before
    /// the Stage-C const refactor and any later storage-model changes.
    /// </summary>
    public class StorageOpReceiveSystemTests
    {
        static (World world, SimulationSystemGroup group) MakeWorld(string name)
        {
            var world = new World(name);
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            group.AddSystemToUpdateList(world.GetOrCreateSystem<StorageOpReceiveSystem>());
            group.SortSystems();
            world.SetTime(new TimeData(elapsedTime: 0f, deltaTime: 1f / 60f));
            return (world, group);
        }

        static Entity MakeContainer(EntityManager em, ushort itemId, int count)
        {
            var e = em.CreateEntity(typeof(SharedStorageContainer));
            var buf = em.AddBuffer<StorageEntry>(e);
            if (itemId != 0)
                buf.Add(new StorageEntry { ItemId = itemId, Count = count });
            return e;
        }

        static void MakeRequest(EntityManager em, byte op, ushort itemId, int count)
        {
            var e = em.CreateEntity();
            em.AddComponentData(e, new StorageOpRequest { Op = op, ItemId = itemId, Count = count });
            em.AddComponentData(e, default(ReceiveRpcCommandRequest));
        }

        [Test]
        public void Withdraw_Decrements_Existing_Row_And_Destroys_Request()
        {
            var (world, group) = MakeWorld("StorageWithdrawWorld");
            using (world)
            {
                var em = world.EntityManager;
                var container = MakeContainer(em, itemId: 1, count: 100);
                MakeRequest(em, StorageOp.Withdraw, itemId: 1, count: 30);

                group.Update();

                var buf = em.GetBuffer<StorageEntry>(container);
                Assert.AreEqual(1, buf.Length, "A partial withdraw keeps the row.");
                Assert.AreEqual(70, buf[0].Count, "100 - 30 = 70 must remain.");

                using var reqQuery = em.CreateEntityQuery(typeof(StorageOpRequest));
                Assert.AreEqual(0, reqQuery.CalculateEntityCount(),
                    "The handled request entity must be destroyed by the system's ECB.");
            }
        }

        [Test]
        public void Deposit_Of_New_Item_Appends_A_Row()
        {
            var (world, group) = MakeWorld("StorageDepositWorld");
            using (world)
            {
                var em = world.EntityManager;
                var container = MakeContainer(em, itemId: 1, count: 100);
                MakeRequest(em, StorageOp.Deposit, itemId: 2, count: 20);

                group.Update();

                var buf = em.GetBuffer<StorageEntry>(container);
                Assert.AreEqual(2, buf.Length, "Depositing a previously-absent item appends a second row.");
                int item2 = -1;
                for (int i = 0; i < buf.Length; i++)
                    if (buf[i].ItemId == 2) item2 = buf[i].Count;
                Assert.AreEqual(20, item2, "The appended row carries the deposited count.");
            }
        }

        [Test]
        public void Withdraw_Of_Full_Stack_Drops_The_Row()
        {
            var (world, group) = MakeWorld("StorageWithdrawZeroWorld");
            using (world)
            {
                var em = world.EntityManager;
                var container = MakeContainer(em, itemId: 1, count: 30);
                MakeRequest(em, StorageOp.Withdraw, itemId: 1, count: 30);

                group.Update();

                var buf = em.GetBuffer<StorageEntry>(container);
                Assert.AreEqual(0, buf.Length, "Withdrawing the whole stack drops the row entirely.");
            }
        }
    }
}