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 <see cref="GeyserEruptSystem"/> (Geyser_Build_Spec; design-review
    /// wf_900e9965-8f0). Pins the review-hardened contract: an ELAPSED geyser radius-damages LIVING players AND
    /// enemies (friendly fire) with SourceNetworkId = -1, RESCHEDULES NextEruptTick = now + period (never +=, never
    /// the 0 sentinel), and is NEVER destroyed (opposite of the barrel). The load-bearing HIGH regression: a geyser
    /// that ships an UNSTAMPED NextEruptTick (0) must NEVER erupt — the inverted guard lazy-stamps it born-correct
    /// instead of the party-wiping per-tick barrage that copying the barrel's invalid-guard verbatim would cause.
    /// </summary>
    public class GeyserEruptSystemTests
    {
        const uint T0 = 1000;

        static (World world, SimulationSystemGroup group) MakeWorld(string name, uint serverTick = T0)
        {
            var world = new World(name);
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            group.AddSystemToUpdateList(world.GetOrCreateSystem<GeyserEruptSystem>());
            group.SortSystems();
            world.SetTime(new TimeData(elapsedTime: 0f, deltaTime: 1f / 60f));
            var nt = world.EntityManager.CreateEntity(typeof(NetworkTime));
            world.EntityManager.SetComponentData(nt, new NetworkTime { ServerTick = new NetworkTick(serverTick) });
            return (world, group);
        }

        static Entity MakeGeyser(EntityManager em, float3 pos, uint nextEruptTick)
        {
            var e = em.CreateEntity();
            em.AddComponentData(e, LocalTransform.FromPosition(pos));
            em.AddComponentData(e, new Geyser { NextEruptTick = nextEruptTick });
            return e;
        }

        static Entity MakePlayer(EntityManager em, float3 pos, float health, byte region)
        {
            var e = em.CreateEntity();
            em.AddComponentData(e, LocalTransform.FromPosition(pos));
            em.AddComponentData(e, new PlayerTag());
            em.AddComponentData(e, new Health { Current = health, Max = 130f });
            em.AddComponentData(e, new RegionTag { Region = region });
            em.AddBuffer<DamageEvent>(e);
            return e;
        }

        static Entity MakeEnemy(EntityManager em, float3 pos, float health)
        {
            var e = em.CreateEntity();
            em.AddComponentData(e, LocalTransform.FromPosition(pos));
            em.AddComponentData(e, new EnemyTag());
            em.AddComponentData(e, new Health { Current = health, Max = 30f });
            em.AddBuffer<DamageEvent>(e);
            return e;
        }

        [Test]
        public void Elapsed_Geyser_Damages_Living_Both_Sides_Reschedules_And_Survives()
        {
            var (world, group) = MakeWorld("EruptBoth");
            using (world)
            {
                var em = world.EntityManager;
                var geyser = MakeGeyser(em, new float3(10, 0, 10), nextEruptTick: T0); // due exactly now
                var player = MakePlayer(em, new float3(11, 0, 10), health: 100f, region: RegionId.Expedition);
                var enemy = MakeEnemy(em, new float3(10, 0, 12), health: 30f);

                group.Update();

                Assert.IsTrue(em.Exists(geyser), "A geyser is PERMANENT — it is never destroyed on erupt.");
                var pd = em.GetBuffer<DamageEvent>(player);
                Assert.AreEqual(1, pd.Length, "Friendly fire: the living expedition player in radius is hit.");
                Assert.AreEqual(Tuning.GeyserEruptDamage, pd[0].Amount);
                Assert.AreEqual(-1, pd[0].SourceNetworkId, "Environment convention: never a player id.");
                Assert.AreNotEqual(0u, pd[0].SourceTick, "SourceTick stamped at NOW (the authored-tick contract).");
                Assert.AreEqual(1, em.GetBuffer<DamageEvent>(enemy).Length, "The living enemy in radius is hit too (bait mechanic).");

                Assert.AreEqual(TickUtil.NonZero(T0 + Tuning.GeyserPeriodTicks), em.GetComponentData<Geyser>(geyser).NextEruptTick,
                    "Reschedule = now + period (never += ; never the 0 sentinel).");
            }
        }

        [Test]
        public void Unstamped_Geyser_Never_Erupts_And_Is_Lazy_Stamped()
        {
            // The HIGH regression: a baked-0 NextEruptTick at a high serverTick must NOT storm (the inverted guard).
            var (world, group) = MakeWorld("UnstampedNoStorm", serverTick: 5000);
            using (world)
            {
                var em = world.EntityManager;
                var geyser = MakeGeyser(em, new float3(10, 0, 10), nextEruptTick: 0u); // unstamped
                var player = MakePlayer(em, new float3(10, 0, 10), health: 130f, region: RegionId.Expedition);

                group.Update();

                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(player).Length,
                    "An unstamped (0) geyser must NEVER erupt — no per-tick barrage.");
                Assert.AreEqual(TickUtil.NonZero(5000u + Tuning.GeyserPeriodTicks), em.GetComponentData<Geyser>(geyser).NextEruptTick,
                    "0 is lazy-stamped born-correct (now + period) instead of erupting.");
                Assert.IsTrue(em.Exists(geyser));
            }
        }

        [Test]
        public void Dead_Player_And_Out_Of_Radius_Get_Nothing()
        {
            var (world, group) = MakeWorld("EruptFilters");
            using (world)
            {
                var em = world.EntityManager;
                MakeGeyser(em, new float3(10, 0, 10), nextEruptTick: T0);
                var deadPlayer = MakePlayer(em, new float3(10.5f, 0, 10), health: 0f, region: RegionId.Expedition);
                var basePlayer = MakePlayer(em, new float3(10.5f, 0, 10), health: 100f, region: RegionId.Base);
                var farEnemy = MakeEnemy(em, new float3(10 + Tuning.GeyserEruptRadius + 1f, 0, 10), health: 30f);

                group.Update();

                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(deadPlayer).Length, "A dead player in radius gets NOTHING.");
                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(basePlayer).Length, "A non-expedition player gets NOTHING.");
                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(farEnemy).Length, "Out of radius gets nothing.");
            }
        }

        [Test]
        public void Unelapsed_Geyser_Does_Nothing_And_Keeps_Counting_Down()
        {
            var (world, group) = MakeWorld("EruptWait");
            using (world)
            {
                var em = world.EntityManager;
                var geyser = MakeGeyser(em, new float3(10, 0, 10), nextEruptTick: T0 + 120); // still counting down
                var player = MakePlayer(em, new float3(10, 0, 10), health: 100f, region: RegionId.Expedition);

                group.Update();

                Assert.AreEqual(0, em.GetBuffer<DamageEvent>(player).Length, "No damage before the eruption tick.");
                Assert.AreEqual(T0 + 120, em.GetComponentData<Geyser>(geyser).NextEruptTick, "An un-elapsed geyser is not rescheduled.");
            }
        }
    }
}