CounterDroneBackend/test/unit/CounterDrone.Core.Tests/DispersionModelTests.cs

using CounterDrone.Core.Algorithms;
using CounterDrone.Core.Models;
using Xunit;

namespace CounterDrone.Core.Tests
{
    public class DispersionModelTests
    {
        private static AmmunitionSpec Ammo() => TestData.Defaults.Ammunition.First(a => a.AerosolType == (int)AerosolType.InertGas);

        [Fact]
        public void Phase1_InitialRadius_FromBurstCharge()
        {
            var m = new GaussianPuffDispersion();
            m.Initialize(Ammo(), new CombatScene { WindSpeed = 0 }, new Algorithms.Vector3(0, 0, 0), 0f);
            // R₀ = 3.3 × 0.3^0.32 ≈ 2.2m
            Assert.True(m.Radius > 1.5f && m.Radius < 5f, $"R₀={m.Radius:F2}");
        }

        [Fact]
        public void Phase2_Radius_GrowsWithSqrtT()
        {
            var m = new GaussianPuffDispersion();
            m.Initialize(Ammo(), new CombatScene { WindSpeed = 0 }, new Algorithms.Vector3(0, 0, 0), 0f);
            var r1 = m.Radius;
            m.Tick(9f, 0f, WindDirection.N);
            var r2 = m.Radius;
            m.Tick(7f, 0f, WindDirection.N); // total 16s
            var r3 = m.Radius;
            // 0→9s: Δ = k×3 = 15; 9→16s: Δ = k×(4-3) = 5
            Assert.True(r3 > r2 && r2 > r1, "半径应单调递增");
        }

        [Fact]
        public void Phase2_Density_DropsWithVolume()
        {
            var m = new GaussianPuffDispersion();
            m.Initialize(Ammo(), new CombatScene { WindSpeed = 0 }, new Algorithms.Vector3(0, 0, 0), 0f);
            var d1 = m.CoreDensity;
            m.Tick(10f, 0f, WindDirection.N);
            Assert.True(m.CoreDensity < d1, "膨胀后密度应下降");
        }

        [Fact]
        public void Phase3_SwitchesAfter30s()
        {
            var m = new GaussianPuffDispersion();
            m.Initialize(Ammo(), new CombatScene { WindSpeed = 0 }, new Algorithms.Vector3(0, 0, 0), 0f);
            m.Tick(35f, 0f, WindDirection.N);
            Assert.False(m.IsDissipated, "35s不应消散");
        }

        [Fact]
        public void Dissipates_AfterMaxDuration()
        {
            var m = new GaussianPuffDispersion();
            var a = new AmmunitionSpec
            {
                Id = "test", AerosolType = (int)AerosolType.InertGas,
                InitialRadius = 3.8, CoreDensity = 1.5, EdgeDensity = 0.1,
                InitialTemperature = 1800, BuoyancyFactor = 0.3,
                EffectiveConcentration = 0.0001, MaxRadius = 100, MaxDuration = 2,
                SourceStrength = 10, BurstChargeKg = 1.5, TurbulentExpansionK = 3,
            };
            m.Initialize(a, new CombatScene { WindSpeed = 0 }, new Algorithms.Vector3(0, 0, 0), 0f);
            m.Tick(3f, 0f, WindDirection.N);
            Assert.True(m.IsDissipated);
        }

        [Fact]
        public void DefaultAmmo_ParametersInReasonableRange()
        {
            var inert = TestData.Defaults.Ammunition.First(a => a.AerosolType == (int)AerosolType.InertGas);
            Assert.True(inert.BurstChargeKg is > 0.01 and < 5, "爆发药应 0.01~5kg");
            Assert.True(inert.TurbulentExpansionK is > 1 and < 20, "湍流系数应 1~20");
            Assert.True(inert.EffectiveConcentration is >= 0.0001 and < 0.1, "有效浓度阈值应 ≥ 0.0001");
            Assert.True(inert.SourceStrength is > 1 and < 100, "源强应 1~100kg");
        }

        // ═══════════════════════════════════════
        // P0 修复：Phase3 高斯扩散应使用环境真实天气的稳定度
        //   原先 Tick 中 GetStabilityClass 写死 (WeatherType)0 (Sunny)，
        //   导致任何天气下 Phase3 扩散行为都相同。
        // ═══════════════════════════════════════

        [Fact]
        public void Phase3_DifferentWeather_ProduceDifferentDensity()
        {
            // 同样风速下，雾天(E稳定)扩散慢 → 浓度高；晴天低风(A极不稳定)扩散快 → 浓度低
            // 两模型都推进到 Phase3 (>30s)，仅天气不同
            float windSpeed = 3f;

            var fogModel = new GaussianPuffDispersion();
            fogModel.Initialize(Ammo(), new CombatScene { WeatherType = (int)WeatherType.Fog, WindSpeed = windSpeed },
                new Algorithms.Vector3(0, 0, 0), 0f);
            fogModel.Tick(40f, windSpeed, WindDirection.N); // 进入 Phase3

            var sunnyModel = new GaussianPuffDispersion();
            sunnyModel.Initialize(Ammo(), new CombatScene { WeatherType = (int)WeatherType.Sunny, WindSpeed = windSpeed },
                new Algorithms.Vector3(0, 0, 0), 0f);
            sunnyModel.Tick(40f, windSpeed, WindDirection.N);

            // 雾天稳定度高 → 云团收得紧 → 中心浓度显著高于晴天低风
            Assert.True(fogModel.CoreDensity > sunnyModel.CoreDensity,
                $"雾天浓度={fogModel.CoreDensity:F6} 应高于晴天={sunnyModel.CoreDensity:F6}（P0: 天气应真实影响扩散）");
        }

        [Fact]
        public void Phase3_Night_MoreStableThanSunny()
        {
            // 夜间(F极稳定) vs 晴天低风(A极不稳定)，风速相同
            float windSpeed = 2f;

            var nightModel = new GaussianPuffDispersion();
            nightModel.Initialize(Ammo(), new CombatScene { WeatherType = (int)WeatherType.Night, WindSpeed = windSpeed },
                new Algorithms.Vector3(0, 0, 0), 0f);
            nightModel.Tick(40f, windSpeed, WindDirection.N);

            var sunnyModel = new GaussianPuffDispersion();
            sunnyModel.Initialize(Ammo(), new CombatScene { WeatherType = (int)WeatherType.Sunny, WindSpeed = windSpeed },
                new Algorithms.Vector3(0, 0, 0), 0f);
            sunnyModel.Tick(40f, windSpeed, WindDirection.N);

            Assert.True(nightModel.CoreDensity > sunnyModel.CoreDensity,
                $"夜间浓度={nightModel.CoreDensity:F6} 应高于晴天={sunnyModel.CoreDensity:F6}");
        }
    }
}