using NUnit.Framework;
using ProjectM.Server;
using ProjectM.Simulation;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;

namespace ProjectM.Tests
{
    /// <summary>
    /// Plain-Entities test for <see cref="UpgradePickupSystem"/> (server grant). A player overlapping a
    /// pickup gets the pickup's modifier appended to its StatModifier buffer and the pickup is destroyed;
    /// a player out of range leaves the buffer empty and the pickup alive. The system's ECB plays back
    /// immediately (server pattern), so no separate ECB system is needed.
    /// </summary>
    public class UpgradePickupSystemTests
    {
        static (World world, Entity player, Entity pickup) MakeWorld(float3 playerPos, float3 pickupPos, float radius)
        {
            var world = new World("UpgradePickupTestWorld");
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            group.AddSystemToUpdateList(world.GetOrCreateSystem<UpgradePickupSystem>());
            group.SortSystems();

            var em = world.EntityManager;

            var player = em.CreateEntity(typeof(PlayerTag), typeof(StatModifier), typeof(LocalTransform));
            em.SetComponentData(player, LocalTransform.FromPosition(playerPos));

            var pickup = em.CreateEntity(typeof(UpgradePickup), typeof(HitRadius), typeof(LocalTransform));
            em.SetComponentData(pickup, LocalTransform.FromPosition(pickupPos));
            em.SetComponentData(pickup, new HitRadius { Value = radius });
            em.SetComponentData(pickup, new UpgradePickup
            {
                Target = (byte)StatTarget.Damage, Op = (byte)ModOp.Flat, Value = 25f, SourceId = 7u
            });

            return (world, player, pickup);
        }

        [Test]
        public void Overlap_Grants_Modifier_And_Destroys_Pickup()
        {
            var (world, player, pickup) = MakeWorld(float3.zero, new float3(0.5f, 0f, 0f), 1f);
            try
            {
                world.GetExistingSystemManaged<SimulationSystemGroup>().Update();
                var buf = world.EntityManager.GetBuffer<StatModifier>(player);
                Assert.AreEqual(1, buf.Length);
                Assert.AreEqual((byte)StatTarget.Damage, buf[0].Target);
                Assert.AreEqual((byte)ModOp.Flat, buf[0].Op);
                Assert.AreEqual(25f, buf[0].Value, 1e-4f);
                Assert.AreEqual(7u, buf[0].SourceId);
                Assert.IsFalse(world.EntityManager.Exists(pickup), "Pickup should be destroyed after grant.");
            }
            finally { world.Dispose(); }
        }

        [Test]
        public void Out_Of_Range_Leaves_Buffer_Empty_And_Pickup_Alive()
        {
            var (world, player, pickup) = MakeWorld(float3.zero, new float3(10f, 0f, 0f), 1f);
            try
            {
                world.GetExistingSystemManaged<SimulationSystemGroup>().Update();
                var buf = world.EntityManager.GetBuffer<StatModifier>(player);
                Assert.AreEqual(0, buf.Length);
                Assert.IsTrue(world.EntityManager.Exists(pickup), "Out-of-range pickup should remain.");
            }
            finally { world.Dispose(); }
        }
    }
}