using System;
using System.Collections.Generic;
using System.Linq;
using CounterDrone.Core.Algorithms;
using CounterDrone.Core.Models;
using Xunit;

namespace CounterDrone.Core.Tests
{
    public class DefensePlannerTests
    {
        private static readonly List<AmmunitionSpec> TestAmmo = DefaultAmmunition.GetAll();

        private static FireUnit MakeGroundUnit(string id, float posX, int munitions = 16)
            => new()
            {
                Id = id, Type = PlatformType.GroundBased,
                Position = new Vector3(posX, 0, 50),
                GunCount = 1, ChannelsPerGun = 16,
                MuzzleVelocity = 800, TotalMunitions = munitions, Cooldown = 5f,
                AmmoTypes = new() { AerosolType.InertGas, AerosolType.ActiveMaterial, AerosolType.ActiveFuel },
            };

        private static FireUnit MakeAirUnit(string id, float posX)
            => new()
            {
                Id = id, Type = PlatformType.AirBased,
                Position = new Vector3(posX, 2500, -2000),
                GunCount = 1, ChannelsPerGun = 16,
                CruiseSpeed = 55, ReleaseAltitude = 1500,
                TotalMunitions = 16, Cooldown = 5f,
                AmmoTypes = new() { AerosolType.InertGas },
            };

        private static DroneGroup MakeThreat(PowerType power = PowerType.Piston, float speed = 120f,
            float startX = 0, float endX = 10000, float alt = 500)
        {
            var t = new DroneGroup
            {
                GroupId = "default",
                Target = new TargetConfig
                {
                    TargetType = (int)TargetType.Piston, PowerType = (int)power,
                    Quantity = 1, TypicalSpeed = speed, TypicalAltitude = alt,
                },
                Waypoints = new List<Waypoint>
                {
                    new() { PosX = startX, PosY = alt, PosZ = 100, Speed = speed },
                    new() { PosX = endX, PosY = alt, PosZ = 100, Speed = speed },
                },
            };
            return t;
        }

        private PlannerResult Plan(List<FireUnit> units, DroneGroup threat,
            CombatScene? env = null)
            => new DefaultDefensePlanner(TestAmmo).Plan(units, new() { threat }, env ?? new CombatScene());

        // ═══════════════════════════════════════
        // 威胁排序
        // ═══════════════════════════════════════

        [Fact] public void Priority_FasterThreat_RanksHigher()
        {
            var a = MakeThreat(speed: 60); a.ArrivalTime = 50; a.ThreatIndex = 2f;
            var b = MakeThreat(speed: 500); b.ArrivalTime = 50; b.ThreatIndex = 16f;
            Assert.True(b.Priority > a.Priority);
        }

        [Fact] public void Priority_EarlierThreat_RanksHigher()
        {
            var a = MakeThreat(); a.ArrivalTime = 20; a.ThreatIndex = 2f;
            var b = MakeThreat(); b.ArrivalTime = 100; b.ThreatIndex = 2f;
            Assert.True(a.Priority > b.Priority);
        }

        // ═══════════════════════════════════════
        // 弹药匹配
        // ═══════════════════════════════════════

        [Fact] public void Ammo_Piston_MatchesInertGas()
            => Assert.Equal(AerosolType.InertGas,
                Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat(PowerType.Piston)).Best.Assignments[0].AmmoType);

        [Fact] public void Ammo_Jet_MatchesActiveMaterial()
            => Assert.Equal(AerosolType.ActiveMaterial,
                Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat(PowerType.Jet, 500)).Best.Assignments[0].AmmoType);

        [Fact] public void Ammo_Electric_MatchesInertGas()
            => Assert.Equal(AerosolType.InertGas,
                Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat(PowerType.Electric)).Best.Assignments[0].AmmoType);

        // ═══════════════════════════════════════
        // 地基弹道：每发 shellTime 因目标位置不同而不同
        // ═══════════════════════════════════════

        [Fact]
        public void Ground_FireTime_VariesPerUnitPosition()
        {
            // 两个单元不同位置 → 飞行时间不同 → 发射时间不同
            var u0 = MakeGroundUnit("u0", 5000);
            var u1 = MakeGroundUnit("u1", 8000);
            var threat = MakeThreat(speed: 120);

            var r0 = Plan(new() { u0 }, threat);
            var r1 = Plan(new() { u1 }, threat);

            float t0 = r0.Best.MergedSchedule[0].FireTime;
            float t1 = r1.Best.MergedSchedule[0].FireTime;
            Assert.NotEqual(t0, t1); // 位置不同 → 弹道不同 → 发射时刻不同
        }

        [Fact]
        public void MultiLane_3Drones_3Lanes_ExactOutput()
        {
            // 3 架无人机横向编队，应生成 3 车道各 11 发
            var threat = MakeThreat(speed: 200);
            threat.Target.Quantity = 3;
            threat.Route = new RoutePlan { FormationMode = (int)Models.FormationMode.Formation, LateralSpacing = 50 };
            threat.Waypoints.Clear();
            threat.Waypoints.Add(new Waypoint { PosX = 0, PosY = 500, PosZ = 0, Speed = 200 });
            threat.Waypoints.Add(new Waypoint { PosX = 20000, PosY = 500, PosZ = 0, Speed = 200 });

            var result = Plan(new() { MakeGroundUnit("u0", 5000), MakeGroundUnit("u1", 5000), MakeGroundUnit("u2", 5000) }, threat);

            var events = result.Best.MergedSchedule.OrderBy(e => e.FireTime).ToList();

            // 打印所有事件
            var lines = events.Select(e => $"{e.FireTime:F2}s Y={e.TargetY:F0} u={e.PlatformIndex}").ToList();
            var dump = string.Join("\n", lines.Take(15)) + $"\n... ({events.Count} total)";

            Assert.True(events.Count >= 30, $"count={events.Count}\n{dump}");
            // 验证时间不等（有错开）
            float first = events[0].FireTime, last = events[^1].FireTime;
            Assert.True(last - first > 2f, $"spread={last-first:F1}s, 应有错开\n{dump}");
        }

        [Fact]
        public void Ground_AllFireTimesPositive() => Assert.All(
            Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat()).Best.MergedSchedule,
            fe => Assert.True(fe.FireTime > 0));

        [Fact]
        public void Ground_AllBeforeArrival()
        {
            var threat = MakeThreat();
            float arrival = threat.GetArrivalTime();
            Assert.All(Plan(new() { MakeGroundUnit("u0", 5000) }, threat).Best.MergedSchedule,
                fe => Assert.True(fe.FireTime < arrival, $"FireTime={fe.FireTime:F1} >= arrival={arrival:F1}"));
        }

        [Fact]
        public void Ground_MuzzleVelocity_InFireEvent()
            => Assert.All(Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat()).Best.MergedSchedule,
                fe => Assert.Equal(800f, fe.MuzzleVelocity));

        [Fact]
        public void Ground_TargetX_OnRoute()
        {
            var threat = MakeThreat(startX: 0, endX: 10000);
            Assert.All(Plan(new() { MakeGroundUnit("u0", 5000) }, threat).Best.MergedSchedule,
                fe => Assert.True(fe.TargetX >= 0 && fe.TargetX <= 10000, $"TargetX={fe.TargetX:F0}"));
        }

        // ═══════════════════════════════════════
        // 空基弹道：平台飞一次，所有弹药同飞行时间
        // ═══════════════════════════════════════

        [Fact]
        public void AirBased_PlatformFliesOnce_SameFlightTime()
        {
            // 同一平台多通道：所有弹药飞行时间相同（平台停在投放点）
            var unit = MakeAirUnit("u0", 3000);
            var result = Plan(new() { unit }, MakeThreat(speed: 120));
            var events = result.Best.MergedSchedule.OrderBy(e => e.FireTime).ToList();
            Assert.True(events.Count >= 3);

            float expectedGap = Kinematics.CloudCoverInterval(40f, 120f, 1f);
            for (int i = 1; i < events.Count; i++)
            {
                float gap = events[i].FireTime - events[i - 1].FireTime;
                Assert.True(Math.Abs(gap - expectedGap) < 0.3f,
                    $"gap[{i}]={gap:F3}, expected {expectedGap:F2}±0.3");
            }
        }

        [Fact]
        public void AirBased_FireTime_BeforeArrival()
        {
            var threat = MakeThreat(speed: 120);
            float arrival = threat.GetArrivalTime();
            Assert.All(Plan(new() { MakeAirUnit("u0", 3000) }, threat).Best.MergedSchedule,
                fe => Assert.True(fe.FireTime < arrival - 40f,
                    $"空基FireTime={fe.FireTime:F1} 应远早于 arrival={arrival:F1}"));
        }

        [Fact]
        public void AirBased_MuzzleVelocity_Zero()
            => Assert.All(Plan(new() { MakeAirUnit("u0", 3000) }, MakeThreat()).Best.MergedSchedule,
                fe => Assert.Equal(0f, fe.MuzzleVelocity));

        [Fact]
        public void AirBased_TargetX_OnRoute()
        {
            var threat = MakeThreat(startX: 0, endX: 10000);
            Assert.All(Plan(new() { MakeAirUnit("u0", 3000) }, threat).Best.MergedSchedule,
                fe => Assert.True(fe.TargetX >= 0 && fe.TargetX <= 10000, $"TargetX={fe.TargetX:F0}"));
        }

        // ═══════════════════════════════════════
        // 分配逻辑
        // ═══════════════════════════════════════

        [Fact]
        public void Allocation_RespectsTotalMunitions()
        {
            var unit = MakeGroundUnit("u0", 5000, munitions: 2); // 只能打 2 发
            var result = Plan(new() { unit }, MakeThreat(speed: 200));
            int totalFired = result.Best.Assignments.Sum(a => a.RoundsFired);
            Assert.True(totalFired <= 2, $"fired={totalFired} > 2 munitions");
        }

        [Fact]
        public void Allocation_MultiUnit_PoolsChannels()
        {
            var result = new DefaultDefensePlanner(TestAmmo).Plan(
                new() { MakeGroundUnit("u0", 5000), MakeGroundUnit("u1", 5100) },
                new() { MakeThreat(speed: 200) }, new CombatScene());
            Assert.True(result.Best.ThreatsEngaged == 1);
            Assert.True(result.Best.MergedSchedule.Count > 1);
        }

        [Fact]
        public void Allocation_IncompatibleAmmo_NotEngaged()
        {
            var unit = new FireUnit
            {
                Id = "u0", Type = PlatformType.GroundBased,
                Position = new Vector3(5000, 0, 50),
                GunCount = 1, ChannelsPerGun = 16, MuzzleVelocity = 800,
                TotalMunitions = 16,
                AmmoTypes = new() { AerosolType.ActiveMaterial }, // 无 InertGas
            };
            var result = Plan(new() { unit }, MakeThreat(PowerType.Piston));
            Assert.Equal(0, result.Best.ThreatsEngaged);
        }

        // ═══════════════════════════════════════
        // 边界
        // ═══════════════════════════════════════

        [Fact] public void Edge_NoUnits_Unengaged() => Assert.Equal(1, new DefaultDefensePlanner(TestAmmo).Plan(new(), new() { MakeThreat() }, new CombatScene()).Best.ThreatsUnengaged);
        [Fact] public void Edge_NoThreats_Empty() => Assert.Equal(0, new DefaultDefensePlanner(TestAmmo).Plan(new() { MakeGroundUnit("u0", 5000) }, new(), new CombatScene()).Best.ThreatsEngaged);

        [Fact]
        public void Edge_OutOfRange_Ground()
        {
            var unit = MakeGroundUnit("u0", 100000); // 极远
            var result = Plan(new() { unit }, MakeThreat());
            Assert.Equal(0, result.Best.ThreatsEngaged);
        }

        [Fact]
        public void Edge_OutOfRange_Air()
        {
            var unit = new FireUnit
            {
                Id = "u0", Type = PlatformType.AirBased,
                Position = new Vector3(100000, 2500, 100000), // 极远
                GunCount = 1, ChannelsPerGun = 4, CruiseSpeed = 10, ReleaseAltitude = 1500,
                TotalMunitions = 4, AmmoTypes = new() { AerosolType.InertGas },
            };
            var result = Plan(new() { unit }, MakeThreat());
            Assert.Equal(0, result.Best.ThreatsEngaged);
        }

        // ═══════════════════════════════════════
        // 多威胁
        // ═══════════════════════════════════════

        [Fact]
        public void MultiThreat_BothEngaged()
        {
            var a = MakeThreat(PowerType.Piston, 120); a.GroupId = "g0";
            var b = MakeThreat(PowerType.Jet, 300); b.GroupId = "g1";
            var result = new DefaultDefensePlanner(TestAmmo).Plan(
                new() { MakeGroundUnit("u0", 5000), MakeGroundUnit("u1", 5100) },
                new() { a, b }, new CombatScene());
            Assert.Equal(2, result.Best.ThreatsEngaged);
        }

        // ═══════════════════════════════════════
        // 临界方案
        // ═══════════════════════════════════════

        [Fact]
        public void Critical_HasAssignments()
        {
            var result = Plan(new() { MakeGroundUnit("u0", 5000) }, MakeThreat());
            Assert.True(result.Critical.Assignments.Count > 0);
            Assert.True(result.Critical.OverallProbability >= 0.4f);
        }
    }
}