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

namespace ProjectM.Tests
{
    /// <summary>
    /// Plain-Entities EditMode tests for the server-only <see cref="ZonePulseSystem"/> (LANTERN Vortex/LightZone).
    /// Guards the Build Spec RS-5 invariants: a player-cast zone damages ENEMIES ONLY (no friendly fire), credits
    /// the CASTER's NetworkId (kills feed KillReward), respects its radius, and despawns on lifetime elapse. The
    /// system reads a NetworkTime singleton (constructed here) and plays its ECB back immediately, so one
    /// group.Update() resolves within a single tick. [WorldSystemFilter] is ignored under manual registration.
    /// </summary>
    public class ZonePulseSystemTests
    {
        const uint kTick = 100; // "now" server tick for the fixture

        static (World world, SimulationSystemGroup group) MakeWorld(string name)
        {
            var world = new World(name);
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            group.AddSystemToUpdateList(world.GetOrCreateSystem<ZonePulseSystem>());
            group.SortSystems();
            world.SetTime(new TimeData(elapsedTime: 0f, deltaTime: 1f / 60f));

            // NetworkTime singleton at a valid, non-zero ServerTick.
            var nt = world.EntityManager.CreateEntity(typeof(NetworkTime));
            world.EntityManager.SetComponentData(nt, new NetworkTime { ServerTick = new NetworkTick(kTick) });
            return (world, group);
        }

        static Entity MakeEnemy(EntityManager em, float3 pos, float hp = 100f)
        {
            var e = em.CreateEntity(typeof(EnemyTag), typeof(Health), typeof(DamageEvent), typeof(LocalTransform));
            em.SetComponentData(e, new Health { Current = hp, Max = hp });
            em.SetComponentData(e, LocalTransform.FromPosition(pos));
            return e;
        }

        static Entity MakeZone(EntityManager em, float3 pos, int casterId, float radius, float dmg, uint nextTick, uint expireTick, byte flags = 0)
        {
            var z = em.CreateEntity(typeof(ZoneEffect), typeof(LocalTransform));
            em.SetComponentData(z, LocalTransform.FromPosition(pos));
            em.SetComponentData(z, new ZoneEffect
            {
                CasterNetworkId = casterId,
                Radius = radius,
                DamagePerPulse = dmg,
                NextTick = nextTick,
                ExpireTick = expireTick,
                Flags = flags,
            });
            return z;
        }

        [Test]
        public void Pulse_Damages_Enemies_In_Radius_Credits_Caster_And_Spares_Players()
        {
            var (world, group) = MakeWorld("ZonePulse_EnemyOnly");
            using (world)
            {
                var em = world.EntityManager;
                var inRange = MakeEnemy(em, new float3(2f, 0f, 0f));
                var outRange = MakeEnemy(em, new float3(20f, 0f, 0f));

                // A living player standing INSIDE the zone must take NO friendly fire.
                var player = em.CreateEntity(typeof(PlayerTag), typeof(Health), typeof(DamageEvent), typeof(LocalTransform));
                em.SetComponentData(player, new Health { Current = 100f, Max = 100f });
                em.SetComponentData(player, LocalTransform.FromPosition(new float3(1f, 0f, 0f)));

                // NextTick == now → DUE this tick (radius 5, 10 dmg/pulse, caster 42, never expires).
                MakeZone(em, float3.zero, casterId: 42, radius: 5f, dmg: 10f, nextTick: kTick, expireTick: 0u);

                group.Update();

                var inBuf = em.GetBuffer<DamageEvent>(inRange);
                Assert.AreEqual(1, inBuf.Length, "An enemy inside the radius takes exactly one pulse.");
                Assert.AreEqual(10f, inBuf[0].Amount, 1e-4f, "Pulse deals DamagePerPulse.");
                Assert.AreEqual(42, inBuf[0].SourceNetworkId, "The pulse credits the caster's NetworkId (kill attribution).");

                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(outRange).Length, "An enemy outside the radius is untouched.");
                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(player).Length, "A player in the zone takes NO friendly fire (enemy-only).");
            }
        }

        [Test]
        public void Born_Zero_NextTick_Lazy_Stamps_And_Does_Not_Storm_Fire()
        {
            var (world, group) = MakeWorld("ZonePulse_BornZero");
            using (world)
            {
                var em = world.EntityManager;
                var enemy = MakeEnemy(em, new float3(1f, 0f, 0f));
                // NextTick 0 = unscheduled: the INVERTED guard must lazy-stamp born-correct, NOT fire this tick.
                var zone = MakeZone(em, float3.zero, casterId: 7, radius: 5f, dmg: 10f, nextTick: 0u, expireTick: 0u);

                group.Update();

                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(enemy).Length,
                    "A born-0 NextTick must lazy-stamp (never storm-fire) on the first tick.");
                Assert.AreNotEqual(0u, em.GetComponentData<ZoneEffect>(zone).NextTick,
                    "NextTick must be stamped born-correct (non-zero) after the first tick.");
            }
        }

        [Test]
        public void Expired_Zone_Is_Despawned()
        {
            var (world, group) = MakeWorld("ZonePulse_Expire");
            using (world)
            {
                var em = world.EntityManager;
                // ExpireTick in the past (50 < now 100) → despawn this tick.
                var zone = MakeZone(em, float3.zero, casterId: 1, radius: 5f, dmg: 10f, nextTick: kTick, expireTick: 50u);

                group.Update();

                Assert.IsFalse(em.Exists(zone), "A zone past its ExpireTick is destroyed (server-authoritative despawn).");
            }
        }
    }
}