using NUnit.Framework;
using ProjectM.Simulation;
using Unity.Collections;
using Unity.Entities;

namespace ProjectM.Tests
{
    /// <summary>
    /// Plain-Entities test for <see cref="StatRecomputeSystem"/>: builds an AbilityDatabase blob singleton
    /// + a player-like entity (refs / modifier buffer / effective components), ticks the
    /// SimulationSystemGroup, and asserts the effective stats equal the folded (base + modifiers) values
    /// and stay stable across repeated ticks (the every-tick recompute is idempotent). Version-independent.
    /// </summary>
    public class StatRecomputeSystemTests
    {
        const byte AbilityPrimary = (byte)AbilityId.Primary;
        const byte CharDefault = (byte)CharacterId.Default;

        static BlobAssetReference<AbilityDatabaseBlob> BuildDb()
        {
            using var b = new BlobBuilder(Allocator.Temp);
            ref var root = ref b.ConstructRoot<AbilityDatabaseBlob>();
            var a = b.Allocate(ref root.Abilities, 1);
            a[0] = new AbilityDefBlob
            {
                Id = AbilityPrimary, Damage = 20f, ProjectileSpeed = 25f, Range = 20f,
                AutoTargetRange = 12f, AutoTargetConeRadians = 0.6f, CooldownTicks = 12, Name = "Primary"
            };
            var c = b.Allocate(ref root.Characters, 1);
            c[0] = new CharacterStatsBlob
            {
                Id = CharDefault, MoveSpeed = 6f, TurnRateRadiansPerSec = 12.5f, MaxHealth = 100f, Name = "Default"
            };
            return b.CreateBlobAssetReference<AbilityDatabaseBlob>(Allocator.Persistent);
        }

        static (World world, Entity player) MakeWorld(out BlobAssetReference<AbilityDatabaseBlob> blob)
        {
            var world = new World("StatRecomputeTestWorld");
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            group.AddSystemToUpdateList(world.GetOrCreateSystem<StatRecomputeSystem>());
            group.SortSystems();

            var em = world.EntityManager;
            blob = BuildDb();
            var dbEntity = em.CreateEntity(typeof(AbilityDatabase));
            em.SetComponentData(dbEntity, new AbilityDatabase { Value = blob });

            var player = em.CreateEntity(
                typeof(AbilityRef), typeof(CharacterStatsRef), typeof(StatModifier),
                typeof(EffectiveAbilityStats), typeof(EffectiveCharacterStats), typeof(Simulate));
            em.SetComponentData(player, new AbilityRef { Id = AbilityPrimary });
            em.SetComponentData(player, new CharacterStatsRef { Id = CharDefault });
            return (world, player);
        }

        static void AddMod(World world, Entity player, StatTarget target, ModOp op, float value)
        {
            var buf = world.EntityManager.GetBuffer<StatModifier>(player);
            buf.Add(new StatModifier { Target = (byte)target, Op = (byte)op, Value = value });
        }

        [Test]
        public void NoModifiers_Effective_Equals_Base()
        {
            var (world, player) = MakeWorld(out var blob);
            try
            {
                world.GetExistingSystemManaged<SimulationSystemGroup>().Update();
                var ea = world.EntityManager.GetComponentData<EffectiveAbilityStats>(player);
                var ec = world.EntityManager.GetComponentData<EffectiveCharacterStats>(player);
                Assert.AreEqual(20f, ea.Damage, 1e-3f);
                Assert.AreEqual(25f, ea.ProjectileSpeed, 1e-3f);
                Assert.AreEqual(12, ea.CooldownTicks);
                Assert.AreEqual(6f, ec.MoveSpeed, 1e-3f);
                Assert.AreEqual(100f, ec.MaxHealth, 1e-3f);
            }
            finally { world.Dispose(); blob.Dispose(); }
        }

        [Test]
        public void Modifiers_Fold_Into_Effective()
        {
            var (world, player) = MakeWorld(out var blob);
            try
            {
                AddMod(world, player, StatTarget.Damage, ModOp.Flat, 5f);
                AddMod(world, player, StatTarget.Damage, ModOp.PercentAdd, 0.5f);    // (20+5)*1.5 = 37.5
                AddMod(world, player, StatTarget.MoveSpeed, ModOp.PercentAdd, 0.5f); // 6*1.5 = 9
                world.GetExistingSystemManaged<SimulationSystemGroup>().Update();
                var ea = world.EntityManager.GetComponentData<EffectiveAbilityStats>(player);
                var ec = world.EntityManager.GetComponentData<EffectiveCharacterStats>(player);
                Assert.AreEqual(37.5f, ea.Damage, 1e-3f);
                Assert.AreEqual(9f, ec.MoveSpeed, 1e-3f);
            }
            finally { world.Dispose(); blob.Dispose(); }
        }

        [Test]
        public void Recompute_Is_Idempotent_Across_Ticks()
        {
            var (world, player) = MakeWorld(out var blob);
            try
            {
                AddMod(world, player, StatTarget.Damage, ModOp.Flat, 10f); // 20+10 = 30
                var group = world.GetExistingSystemManaged<SimulationSystemGroup>();
                group.Update();
                var first = world.EntityManager.GetComponentData<EffectiveAbilityStats>(player).Damage;
                for (int i = 0; i < 5; i++) group.Update();
                var last = world.EntityManager.GetComponentData<EffectiveAbilityStats>(player).Damage;
                Assert.AreEqual(30f, first, 1e-3f);
                Assert.AreEqual(first, last, 1e-4f);
            }
            finally { world.Dispose(); blob.Dispose(); }
        }
    }
}