using NUnit.Framework;
using ProjectM.Simulation;
using Unity.Mathematics;

namespace ProjectM.Tests
{
    /// <summary>
    /// MC-2 pure-math tests for the new EnemyAIMath helpers: BandVelocity (Spitter range-band keep-distance) and
    /// ClusterOffset (swarmer pack placement). No ECS world.
    /// </summary>
    public class EnemyAIMathMC2Tests
    {
        [Test]
        public void BandVelocity_AdvancesWhenTooFar()
        {
            var v = EnemyAIMath.BandVelocity(new float3(0, 1, 0), new float3(20, 1, 0), 5f, 9f, 1.5f);
            Assert.Greater(v.x, 0.1f, "too far -> moves toward the target");
            Assert.AreEqual(0f, v.y, 1e-5f, "planar");
        }

        [Test]
        public void BandVelocity_RetreatsWhenTooClose()
        {
            var v = EnemyAIMath.BandVelocity(new float3(0, 1, 0), new float3(3, 1, 0), 5f, 9f, 1.5f);
            Assert.Less(v.x, -0.1f, "too close -> backs away from the target");
        }

        [Test]
        public void BandVelocity_HoldsInBand()
        {
            var v = EnemyAIMath.BandVelocity(new float3(0, 1, 0), new float3(9, 1, 0), 5f, 9f, 1.5f);
            Assert.AreEqual(0f, math.length(v), 1e-4f, "inside the dead-zone band -> hold and fire");
        }

        [Test]
        public void ClusterOffset_SingleAtCentre_PackSpread()
        {
            var c = new float3(100, 1, 5);
            var single = EnemyAIMath.ClusterOffset(c, 0, 1, 2.5f);
            Assert.AreEqual(c.x, single.x, 1e-5f, "a lone swarmer spawns at the pack centre");
            Assert.AreEqual(c.z, single.z, 1e-5f);
            var a = EnemyAIMath.ClusterOffset(c, 0, 4, 2.5f);
            var b = EnemyAIMath.ClusterOffset(c, 1, 4, 2.5f);
            Assert.Greater(math.distance(a, b), 0.01f, "pack members get distinct offsets");
            var again = EnemyAIMath.ClusterOffset(c, 2, 4, 2.5f);
            Assert.AreEqual(0f, math.distance(again, EnemyAIMath.ClusterOffset(c, 2, 4, 2.5f)), 1e-5f, "deterministic");
        }
    }
}