/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

using System;
using System.IO;
using System.Linq;
using CultMath;
using GameCult.Caching;
using Xunit;
using static CultMath.math;
using float3 = CultMath.float3;
using Random = CultMath.Random;

// Cut 2 (docs/fire-control-cut.md): pins the targeting subsystem, the reveal rule between the two info
// thresholds, the selection slot/predicate, and the required-equipment ruling (Q4). Builds its own
// hull/catalog fixtures, the same style FireControlTests uses for Cut 1, rather than reusing that file's
// or LoadoutTests' private helpers.
public sealed class TargetingSystemTests : IDisposable
{
    private readonly string _root = Path.Combine(Path.GetTempPath(), "aetheria-targeting-" + Guid.NewGuid().ToString("N"));
    private string Catalog => Path.Combine(_root, "Aetheria.cc");

    public TargetingSystemTests() => Directory.CreateDirectory(_root);

    private CultCache _openCache;

    public void Dispose()
    {
        _openCache?.Dispose();
        Directory.Delete(_root, true);
    }

    private static GameplaySettings TestSettings() => new GameplaySettings
    {
        DefaultEntitySettings = new EntitySettings(),
        Tiers = new[] { new RarityTier { Name = "Common", Quality = .5f, Rarity = 0, Color = new float3(1, 1, 1) } },
        QualityPriceModifier = new ExponentialLerp(),
        TargetArmorInfoThreshold = .3f,
        TargetGearInfoThreshold = .9f,
        UnaidedAccuracy = .1f,
        FiringArc = 120
    };

    private static PerformanceStat Constant(float v) => new PerformanceStat { Min = v, Max = v };

    // Min=0 (not Min=Max): a PowerSupply term can only be observed to degrade something with room to move
    // between floor and authored ceiling (BrownoutTests' own convention).
    private static PerformanceStat Curved(float max, float exponent) =>
        new PerformanceStat { Min = 0, Max = max, Terms = { new StatTerm { Source = StatSource.PowerSupply, Exponent = exponent } } };

    // A 6x4 hull with one Sensors hardpoint at (0,0) (hardpoint-mounted weapon) and interior room for two
    // more Tool items, one 2-cell and one 1-cell. Non-hull equipment ends up authored in this order --
    // hardpoint weapon, wide interior item, narrow interior item -- but it is FireControl.IsRevealed's own
    // ranking, not authoring order, that RevealOrder actually pins.
    // `targetingData`, when given, authors a fourth non-hull item (a Tool gear carrying that behaviour) in
    // the same catalog-build pass, so a test that needs a targeting system never has to reopen the catalog
    // file after the live, already-open ItemManager exists (CultCache is single-writer).
    private (ItemManager items, Ship target, EquippedItem weapon, EquippedItem wideItem, EquippedItem narrowItem, EquippedItem targetingItem)
        BuildTarget(GameplaySettings settings, TargetingSystemData targetingData = null)
    {
        var hullShape = new Shape(6, 4);
        foreach (var cell in hullShape.AllCoordinates) hullShape[cell] = true;
        var hullData = new HullData
        {
            Name = "TestHull", HullType = HullType.Ship, Shape = hullShape, Durability = 1, Mass = 1000,
            Hardpoints = { new HardpointData { Type = HardpointType.Sensors, Position = new int2(0, 0), Shape = new Shape() } }
        };

        using (var buildCache = AetheriaStores.Open(Catalog, catalogWritable: true))
        {
            buildCache.Upsert(new VerseGrammar { Revision = 1 });
            buildCache.Upsert(hullData);
            buildCache.Upsert(new GearData
            {
                Name = "Gun", Hardpoint = HardpointType.Sensors, Shape = new Shape(), Durability = 1,
                MinimumTemperature = -1000, MaximumTemperature = 1000, OptimalTemperature = 0, PlateauWidth = 2000,
                Behaviors = { new InstantWeaponData() }
            });
            var wideShape = new Shape(2, 1);
            wideShape[new int2(0, 0)] = true;
            wideShape[new int2(1, 0)] = true;
            buildCache.Upsert(new GearData
            {
                Name = "Wide", Hardpoint = HardpointType.Tool, Shape = wideShape, Durability = 1,
                MinimumTemperature = -1000, MaximumTemperature = 1000, OptimalTemperature = 0, PlateauWidth = 2000
            });
            buildCache.Upsert(new GearData
            {
                Name = "Narrow", Hardpoint = HardpointType.Tool, Shape = new Shape(), Durability = 1,
                MinimumTemperature = -1000, MaximumTemperature = 1000, OptimalTemperature = 0, PlateauWidth = 2000
            });
            if (targetingData != null)
                buildCache.Upsert(new GearData
                {
                    Name = "Targeting", Hardpoint = HardpointType.Tool, Shape = new Shape(), Durability = 1,
                    MinimumTemperature = -1000, MaximumTemperature = 1000, OptimalTemperature = 0, PlateauWidth = 2000,
                    Behaviors = { targetingData }
                });
            buildCache.FlushAsync().Wait();
        }

        _openCache = AetheriaStores.Open(Catalog, catalogWritable: true);
        var ledger = new ProvenanceLedger();
        ledger.Lots[1] = new Lot { Origin = new Attributed(), Quality = 1 }; // hull
        ledger.Lots[2] = new Lot { Origin = new Attributed(), Quality = 1 }; // gun
        ledger.Lots[3] = new Lot { Origin = new Attributed(), Quality = 1 }; // wide
        ledger.Lots[4] = new Lot { Origin = new Attributed(), Quality = 1 }; // narrow
        ledger.Lots[5] = new Lot { Origin = new Attributed(), Quality = 1 }; // targeting (unused unless authored above)
        var items = new ItemManager(_openCache, ledger, settings, _ => { });
        var zone = new Zone(items, new PlanetSettings(), new ZonePack(), new GalaxyZone { Name = "Test Zone", Owner = null }, null);

        var hullRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<HullData>("TestHull"));
        var hull = new EquippableItem { Data = hullRef, Durability = 1, Lot = 1 };
        var target = new Ship(items, zone, hull, new EntitySettings());

        // Cut 7 (docs/fire-control-cut.md, 7.2): equipped in size-ascending, hardpoint-last order -- the
        // opposite of IsRevealed's own ranking (hardpoint-mounted first, then size descending) -- so that
        // dropping the explicit ranking in FireControl.IsRevealed is actually observable. Equipping in
        // rank order let a "drop the ordering, rank by equipment order alone" mutation pass: Entity.Equipment
        // already happened to enumerate in the correct final order by sheer coincidence of authoring order,
        // so RevealOrder's own assertions never distinguished the ranked read from the raw one.
        var narrowRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<GearData>("Narrow"));
        var narrow = new EquippableItem { Data = narrowRef, Durability = 1, Lot = 4 };
        Assert.True(target.TryFindSpace(narrow, out var narrowPos));
        Assert.True(target.TryEquip(narrow, narrowPos));
        var narrowItem = target.Equipment.Single(e => e.EquippableItem == narrow);

        var wideRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<GearData>("Wide"));
        var wide = new EquippableItem { Data = wideRef, Durability = 1, Lot = 3 };
        Assert.True(target.TryFindSpace(wide, out var widePos));
        Assert.True(target.TryEquip(wide, widePos));
        var wideItem = target.Equipment.Single(e => e.EquippableItem == wide);

        var gunRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<GearData>("Gun"));
        var gun = new EquippableItem { Data = gunRef, Durability = 1, Lot = 2 };
        Assert.True(target.TryEquip(gun, new int2(0, 0)));
        var weapon = target.Equipment.Single(e => e.EquippableItem == gun);

        EquippedItem targetingItem = null;
        if (targetingData != null)
        {
            var targetingRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<GearData>("Targeting"));
            var targeting = new EquippableItem { Data = targetingRef, Durability = 1, Lot = 5 };
            Assert.True(target.TryFindSpace(targeting, out var targetingPos));
            Assert.True(target.TryEquip(targeting, targetingPos));
            targetingItem = target.Equipment.Single(e => e.EquippableItem == targeting);
        }

        zone.Entities.Add(target);
        target.Activate();

        return (items, target, weapon, wideItem, narrowItem, targetingItem);
    }

    // A bare-hull observer sharing the target's zone, with no equipment of its own -- only its
    // EntityInfoGathered dictionary and Target/TrySelectTargetItem matter to these tests.
    private Ship BuildObserver(ItemManager items, Zone zone)
    {
        var hullRef = items.ItemData.RefOf<ItemData>(items.ItemData.GetByName<HullData>("TestHull"));
        var hull = new EquippableItem { Data = hullRef, Durability = 1, Lot = 1 };
        var observer = new Ship(items, zone, hull, new EntitySettings());
        zone.Entities.Add(observer);
        observer.Activate();
        return observer;
    }

    // R5 / the selection predicate: TrySelectTargetItem accepts only a revealed item of the current target,
    // a Target change nulls the aim point, and decay drops it on read with no loop clearing it.
    // Mutation: IsRevealed returns true unconditionally; the Target-change subscription is removed; or
    // ResolvedTargetItem returns TargetItem.Value without re-checking.
    [Fact]
    public void SelectionNeedsReveal()
    {
        var (items, target, weapon, _, _, _) = BuildTarget(TestSettings());
        var observer = BuildObserver(items, target.Zone);
        observer.SetTarget(target);

        observer.EntityInfoGathered[target] = .29f; // below the single item's own tier (Armor, N==1)
        Assert.False(observer.TrySelectTargetItem(weapon));
        Assert.Null(observer.TargetItem.Value);

        observer.EntityInfoGathered[target] = .3f; // at tier: revealed
        Assert.True(observer.TrySelectTargetItem(weapon));
        Assert.Same(weapon, observer.TargetItem.Value);
        Assert.Same(weapon, observer.ResolvedTargetItem);

        // A Target change nulls the aim point.
        observer.SetTarget(TargetRef.None);
        Assert.Null(observer.TargetItem.Value);

        // Decay: re-select, then let info fall back below tier without touching TargetItem.Value at all --
        // the raw field still holds the item (no loop cleared it), but the read accessor drops it.
        observer.SetTarget(target);
        Assert.True(observer.TrySelectTargetItem(weapon));
        observer.EntityInfoGathered[target] = .1f;
        Assert.Same(weapon, observer.TargetItem.Value);
        Assert.Null(observer.ResolvedTargetItem);
    }

    // The ranking: hardpoint-mounted gear before interior Tool gear, larger before smaller within a group.
    // Mutation: drop the ordering (e.g. rank by equipment order alone).
    [Fact]
    public void RevealOrder()
    {
        var (items, target, weapon, wideItem, narrowItem, _) = BuildTarget(TestSettings());
        var observer = BuildObserver(items, target.Zone);

        observer.EntityInfoGathered[target] = .35f; // above Armor (.3, index 0), below the mid tier (.6, index 1)
        Assert.True(FireControl.IsRevealed(observer, weapon));
        Assert.False(FireControl.IsRevealed(observer, wideItem));
        Assert.False(FireControl.IsRevealed(observer, narrowItem));

        observer.EntityInfoGathered[target] = .65f; // above the mid tier, below Gear (.9, index 2)
        Assert.True(FireControl.IsRevealed(observer, weapon));
        Assert.True(FireControl.IsRevealed(observer, wideItem));
        Assert.False(FireControl.IsRevealed(observer, narrowItem));

        observer.EntityInfoGathered[target] = .95f; // above Gear: everything revealed
        Assert.True(FireControl.IsRevealed(observer, weapon));
        Assert.True(FireControl.IsRevealed(observer, wideItem));
        Assert.True(FireControl.IsRevealed(observer, narrowItem));
    }

    // The tiers really are the two authored settings: the first item reveals exactly at
    // TargetArmorInfoThreshold, the last exactly at TargetGearInfoThreshold. Mutation: swap the two
    // settings, or use TargetDetectionInfoThreshold instead.
    [Fact]
    public void RevealSpansBothThresholds()
    {
        var settings = TestSettings();
        var (items, target, weapon, wideItem, narrowItem, _) = BuildTarget(settings);
        var observer = BuildObserver(items, target.Zone);

        observer.EntityInfoGathered[target] = settings.TargetArmorInfoThreshold;
        Assert.True(FireControl.IsRevealed(observer, weapon));
        Assert.False(FireControl.IsRevealed(observer, wideItem));
        Assert.False(FireControl.IsRevealed(observer, narrowItem));

        observer.EntityInfoGathered[target] = settings.TargetGearInfoThreshold;
        Assert.True(FireControl.IsRevealed(observer, weapon));
        Assert.True(FireControl.IsRevealed(observer, wideItem));
        Assert.True(FireControl.IsRevealed(observer, narrowItem));
    }

    // Q4: the subsystem is what supplies accuracy. No targeting system, a destroyed one, and a disabled one
    // all resolve the authored unaided figures. Mutation: fall back to the (destroyed/offline) system's own
    // stats instead of the unaided ones.
    [Fact]
    public void UnaidedFiresWorse()
    {
        var settings = TestSettings();

        var targetingData = new TargetingSystemData
        {
            Accuracy = Constant(.8f), Resolution = Constant(.6f), Precision = Constant(.7f), Tracking = Constant(.5f)
        };
        var (items, target, _, _, _, targetingUnit) = BuildTarget(settings, targetingData);
        var equippedTargeting = targetingUnit;
        var system = equippedTargeting.Behaviors.OfType<TargetingSystem>().Single();
        system.Execute(0f);

        // No targeting system at all: a second, bare-hull ship in the same catalog/zone (one CultCache
        // handle stays open per test -- BuildTarget is not called twice).
        var bareShip = BuildObserver(items, target.Zone);
        Assert.Equal(settings.UnaidedAccuracy, FireControl.Accuracy(bareShip), 4);
        // Cut 6d (docs/fire-control-cut.md): Precision now falls back to UnaidedPrecision, the same shape as
        // Accuracy/Tracking above -- it used to fall back to a bare 0, which was fine when Precision only fed
        // the old coin-flip's aimed-item branch and meant nothing to a shot with no aim point. Now it derives
        // every shot's sigma, aimed or not, so the unaided floor has to be an authored number, not a bare zero.
        Assert.Equal(settings.UnaidedPrecision, FireControl.Precision(bareShip), 4);
        Assert.Equal(1f, FireControl.Resolution(bareShip), 4);

        // Bring it online to prove the fixture can actually supply its own stats...
        equippedTargeting.UpdatePerformance();
        Assert.True(equippedTargeting.Active.Value);
        Assert.Equal(.8f, FireControl.Accuracy(target), 4);
        Assert.Equal(.7f, FireControl.Precision(target), 4);

        // ...then destroy it: durability gone, still falls back.
        equippedTargeting.EquippableItem.Durability = 0f;
        equippedTargeting.UpdatePerformance();
        Assert.False(equippedTargeting.Active.Value);
        Assert.Equal(settings.UnaidedAccuracy, FireControl.Accuracy(target), 4);
        Assert.Equal(settings.UnaidedPrecision, FireControl.Precision(target), 4);
        Assert.Equal(1f, FireControl.Resolution(target), 4);

        // Repair it, then disable it directly instead: same fallback.
        equippedTargeting.EquippableItem.Durability = 1f;
        equippedTargeting.UpdatePerformance();
        Assert.True(equippedTargeting.Active.Value);
        equippedTargeting.Enabled.Value = false;
        Assert.False(equippedTargeting.Active.Value);
        Assert.Equal(settings.UnaidedAccuracy, FireControl.Accuracy(target), 4);
        Assert.Equal(settings.UnaidedPrecision, FireControl.Precision(target), 4);
    }

    // The brownout ruling (docs/stats-and-power-cut.md) applies to Accuracy same as any other stat: a
    // half-grant halves it (PowerSupply exponent 1), not a switch-off. Reactor + a real PowerBus tick, the
    // same fixture shape BrownoutTests uses, because Item.PowerSupply's setter is internal to a different
    // assembly here and can only be driven through a live grant.
    [Fact]
    public void StarvedTargetingRollsWorse()
    {
        using var cache = AetheriaStores.Open(Catalog, catalogWritable: true);
        cache.Upsert(new VerseGrammar { Revision = 1 });
        var hullShape = new Shape(5, 5);
        foreach (var cell in hullShape.AllCoordinates) hullShape[cell] = true;
        cache.Upsert(new HullData { Name = "Skiff", HullType = HullType.Ship, Shape = hullShape, Durability = 10, Mass = 1000 });
        cache.Upsert(new GearData
        {
            Name = "Reactor", Hardpoint = HardpointType.Tool, Shape = new Shape(), Durability = 10,
            MinimumTemperature = 0, MaximumTemperature = 1000, OptimalTemperature = 280, PlateauWidth = 400,
            Behaviors = { new ReactorData { Charge = Constant(0), Efficiency = Constant(1), OverloadEfficiency = Constant(1), ThrottlingFactor = Constant(2) } }
        });
        cache.Upsert(new GearData
        {
            Name = "Targeting", Hardpoint = HardpointType.Tool, Shape = new Shape(), Durability = 10,
            MinimumTemperature = 0, MaximumTemperature = 1000, OptimalTemperature = 280, PlateauWidth = 400,
            Behaviors =
            {
                new EnergyDrawData { EnergyDraw = Constant(100) },
                new TargetingSystemData { Accuracy = Curved(1, 1), Resolution = Constant(1), Precision = Constant(1), Tracking = Constant(1) }
            }
        });
        cache.FlushAsync().Wait();

        EquippableItem Mint(ItemData design) => new EquippableItem
        {
            Data = cache.RefOf<ItemData>(design),
            Durability = design is EquippableItemData equippable ? equippable.Durability : 0,
        };

        Ship BuildShip(float reactorCharge, out ItemManager items)
        {
            items = new ItemManager(cache, new ProvenanceLedger(), TestSettings(), _ => { });
            var zone = new Zone(items, new PlanetSettings(), new ZonePack(), new GalaxyZone { Name = "Test Zone", Owner = null }, null);
            var hullData = cache.GetByName<HullData>("Skiff");
            var hull = Mint(hullData);
            hull.Lot = items.Lots.Add(new Lot { Design = cache.RefOf<ItemData>(hullData), Origin = new Attributed(), Quality = .5f, Roles = new System.Collections.Generic.List<RoleFill>() });
            var ship = new Ship(items, zone, hull, new EntitySettings());

            var reactorData = cache.GetByName<GearData>("Reactor");
            ((ReactorData) reactorData.Behaviors[0]).Charge = Constant(reactorCharge);
            var reactor = Mint(reactorData);
            reactor.Lot = items.Lots.Add(new Lot { Design = cache.RefOf<ItemData>(reactorData), Origin = new Attributed(), Quality = .5f, Roles = new System.Collections.Generic.List<RoleFill>() });
            Assert.True(ship.TryEquip(reactor));

            var targetingData = cache.GetByName<GearData>("Targeting");
            var targeting = Mint(targetingData);
            targeting.Lot = items.Lots.Add(new Lot { Design = cache.RefOf<ItemData>(targetingData), Origin = new Attributed(), Quality = .5f, Roles = new System.Collections.Generic.List<RoleFill>() });
            Assert.True(ship.TryEquip(targeting));

            zone.Entities.Add(ship);
            ship.Aim = float3(0, 0, 1);
            ship.Activate();
            return ship;
        }

        float ResolveAccuracy(float reactorCharge)
        {
            var ship = BuildShip(reactorCharge, out _);
            ship.Update(1f); // one tick: PowerBus.Step grants, then Execute resolves Accuracy against it
            return FireControl.Accuracy(ship);
        }

        var full = ResolveAccuracy(1000); // demand 100, generation far exceeds it -> ratio 1
        var half = ResolveAccuracy(50);   // demand 100, generation 50 -> ratio .5

        Assert.Equal(1f, full, 3);
        Assert.Equal(.5f, half, 3);
    }

    // Q4: required equipment for anything that can fire. Across several seeds, every generated loadout with
    // a weapon also carries a targeting system. Mutation: drop `required: true` on the targeting-system
    // RandomProduct call in LoadoutGenerator.FillInterior.
    [Fact]
    public void EveryArmedLoadoutGetsATargetingSystem()
    {
        using var cache = AetheriaStores.Open(Catalog, catalogWritable: true);
        cache.Upsert(new VerseGrammar { Revision = 1 });
        var maker = cache.Upsert(new Faction { Name = "Maker", ShortName = "MKR" });

        var hullShape = new Shape(5, 5);
        foreach (var cell in hullShape.AllCoordinates) hullShape[cell] = true;
        var hull = cache.Upsert(new HullData
        {
            Name = "Armed", HullType = HullType.Ship, Shape = hullShape, Price = 100,
            Hardpoints = { new HardpointData { Type = HardpointType.Sensors, Position = new int2(0, 0), Shape = new Shape() } }
        });
        var gun = cache.Upsert(new GearData { Name = "Gun", Hardpoint = HardpointType.Sensors, Shape = new Shape(), Price = 1, Behaviors = { new InstantWeaponData() } });
        var cargo = cache.Upsert(new CargoBayData { Name = "Crate", Shape = new Shape(), InteriorShape = new Shape(), Price = 5 });
        var capacitor = cache.Upsert(new GearData { Name = "Cap", Hardpoint = HardpointType.Tool, Shape = new Shape(), Price = 1, Behaviors = { new CapacitorData() } });
        var targeting = cache.Upsert(new GearData { Name = "Targeting", Hardpoint = HardpointType.Tool, Shape = new Shape(), Price = 1, Behaviors = { new TargetingSystemData() } });

        foreach (var (name, design) in new[]
                 {
                     ("Armed by Maker", hull.Key), ("Gun by Maker", gun.Key), ("Crate by Maker", cargo.Key),
                     ("Cap by Maker", capacitor.Key), ("Targeting by Maker", targeting.Key)
                 })
            cache.Upsert(new FactionProductData { Name = name, Design = new CultRecordRef<CraftedItemData>(design), Manufacturer = maker });
        cache.FlushAsync().Wait();

        for (var seed = 1; seed <= 10; seed++)
        {
            var random = new Random((uint) seed);
            var items = new ItemManager(cache, new ProvenanceLedger(), TestSettings(), _ => { });
            var generator = new LoadoutGenerator(ref random, items, null, null, null, .5f);
            var pack = generator.GenerateShipLoadout(candidate => candidate.Name == "Armed");
            Assert.NotNull(pack);
            Assert.Contains(pack.Equipment, e => (cache.Get(e.item.Data) as GearData)?.Behaviors.Any(b => b is TargetingSystemData) ?? false);
        }
    }
}