PkmnLib.NET/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/MagmaStormTests.cs

using PkmnLib.Dynamic.Models;
using PkmnLib.Dynamic.Models.Choices;
using PkmnLib.Dynamic.ScriptHandling;
using PkmnLib.Dynamic.ScriptHandling.Registry;
using PkmnLib.Plugin.Gen7.Scripts;
using PkmnLib.Plugin.Gen7.Scripts.Moves;
using PkmnLib.Plugin.Gen7.Scripts.Pokemon;
using PkmnLib.Static;
using PkmnLib.Static.Utils;

namespace PkmnLib.Plugin.Gen7.Tests.Scripts.Moves;

/// <summary>
/// Tests for the <see cref="MagmaStorm"/> move script and its <see cref="MagmaStormEffect"/> volatile.
/// Gen VII Bulbapedia behavior: Magma Storm deals damage and binds the target. Generation IV: "A bound target
/// cannot switch out or flee, and takes damage ... at the end of each turn." Generation V: the trapping
/// duration changed to four to five turns. Generations VI and VII: the per-turn damage is increased to 1/8 of
/// the target's maximum HP, a Binding Band boosts it to 1/6, and "Ghost-type Pokémon cannot be trapped by
/// Magma Storm."
/// The trapping and end-of-turn damage themselves are implemented by the <see cref="MagmaStormEffect"/>
/// volatile; the move script determines the duration and damage fraction through the
/// <see cref="CustomTriggers.ModifyBind"/> custom trigger and applies the volatile to the target.
/// </summary>
public class MagmaStormTests
{
    /// <summary>
    /// Test helper script that modifies the bind duration/damage through the
    /// <see cref="CustomTriggers.ModifyBind"/> custom trigger, the same way the Grip Claw and Binding Band
    /// item scripts do.
    /// </summary>
    [Script(ScriptCategory.Pokemon, "test_modify_magma_storm_bind_trigger")]
    private class ModifyBindTrigger : Script, IScriptCustomTrigger
    {
        private readonly int? _duration;
        private readonly float? _damagePercent;

        public ModifyBindTrigger(int? duration = null, float? damagePercent = null)
        {
            _duration = duration;
            _damagePercent = damagePercent;
        }

        public void CustomTrigger(StringKey eventName, ICustomTriggerArgs args)
        {
            if (eventName != CustomTriggers.ModifyBind || args is not CustomTriggers.ModifyBindArgs bindArgs)
                return;
            if (_duration.HasValue)
                bindArgs.Duration = _duration.Value;
            if (_damagePercent.HasValue)
                bindArgs.DamagePercent = _damagePercent.Value;
        }
    }

    /// <summary>
    /// Creates a fully mocked test setup for Magma Storm tests. The target gets a real
    /// <see cref="ScriptSet"/> as its volatile set, so the applied effect can be inspected. The user's script
    /// iterator is real but empty unless the test attaches scripts (such as the Grip Claw / Binding Band
    /// stand-in), so the <see cref="CustomTriggers.ModifyBind"/> trigger pass runs.
    /// </summary>
    private static (MagmaStorm script, IExecutingMove move, IPokemon target, IScriptSet targetVolatile) CreateTestSetup(
        params Script[] userScripts)
    {
        var script = new MagmaStorm();
        var move = Substitute.For<IExecutingMove>();
        var target = Substitute.For<IPokemon>();
        target.GetScripts().Returns(_ => new ScriptIterator(new List<IEnumerable<ScriptContainer>>()));
        var targetVolatile = new ScriptSet(target);
        target.Volatile.Returns(targetVolatile);

        var user = Substitute.For<IPokemon>();
        var containers = userScripts.Select(IEnumerable<ScriptContainer> (s) => new ScriptContainer(s)).ToArray();
        user.GetScripts().Returns(_ => new ScriptIterator(containers));
        move.User.Returns(user);

        return (script, move, target, targetVolatile);
    }

    /// <summary>
    /// Bulbapedia: "Magma Storm deals damage and binds the target". The move script applies the
    /// <see cref="MagmaStormEffect"/> volatile, which implements the trap, to the target that was hit.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_MoveHits_AddsMagmaStormEffectToTargetVolatile()
    {
        // Arrange
        var (script, move, target, targetVolatile) = CreateTestSetup();

        // Act
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        await Assert.That(targetVolatile.Get<MagmaStormEffect>()).IsNotNull();
    }

    /// <summary>
    /// Technical test: hitting a target that is already trapped by Magma Storm does not add a second
    /// <see cref="MagmaStormEffect"/>; the existing volatile is reused.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_TargetAlreadyTrapped_DoesNotAddSecondEffect()
    {
        // Arrange
        var (script, move, target, targetVolatile) = CreateTestSetup();

        // Act
        script.OnSecondaryEffect(move, target, 0);
        script.OnSecondaryEffect(move, target, 0);

        // Assert
        await Assert.That(targetVolatile.Count).IsEqualTo(1);
    }

    // ----- MagmaStormEffect behavior (the volatile the move applies) -----

    /// <summary>
    /// Creates a trapped Pokémon substitute with the given maximum HP, together with the
    /// <see cref="MagmaStormEffect"/> that traps it.
    /// </summary>
    private static (MagmaStormEffect effect, IPokemon owner) CreateTrappedPokemon(uint maxHealth,
        float percentOfMaxHealth = 1f / 8f)
    {
        var owner = Substitute.For<IPokemon>();
        owner.MaxHealth.Returns(maxHealth);
        owner.Types.Returns(new List<TypeIdentifier> { new(10, "fire") });
        return (new MagmaStormEffect(owner, 5, percentOfMaxHealth), owner);
    }

    /// <summary>
    /// Helper to extract the damage amount from a Pokémon's received Damage calls.
    /// </summary>
    private static uint? GetDamageAmount(IPokemon pokemon)
    {
        var call = pokemon.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "Damage");
        return call != null ? (uint)call.GetArguments()[0]! : null;
    }

    /// <summary>
    /// Runs end-of-turn handling on the effect repeatedly and counts how many turns dealt damage to the target.
    /// </summary>
    private static int CountEndTurnDamageTicks(MagmaStormEffect effect, IPokemon target, int maxTurns = 10)
    {
        var battle = Substitute.For<IBattle>();
        for (var i = 0; i < maxTurns; i++)
            effect.OnEndTurn(target, battle);
        return target.ReceivedCalls().Count(c => c.GetMethodInfo().Name == "Damage");
    }

    /// <summary>
    /// Bulbapedia (Generations VI and VII): the damage taken by the bound target at the end of each turn is
    /// increased from 1/16 to 1/8 of its maximum HP.
    /// </summary>
    [Test, Arguments(96u, 12u), Arguments(100u, 12u), Arguments(120u, 15u), Arguments(8u, 1u)]
    public async Task OnEndTurn_TrappedPokemon_TakesOneEighthOfMaxHpAsDamage(uint maxHealth, uint expectedDamage)
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(maxHealth);

        // Act
        effect.OnEndTurn(owner, Substitute.For<IBattle>());

        // Assert
        await Assert.That(GetDamageAmount(owner)!.Value).IsEqualTo(expectedDamage);
    }

    /// <summary>
    /// Bulbapedia (Generation IV): the bound target "takes damage ... at the end of each turn"; the damage is
    /// dealt once per turn, not more.
    /// </summary>
    [Test]
    public async Task OnEndTurn_TrappedPokemon_TakesDamageOncePerTurn()
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(96);

        // Act
        effect.OnEndTurn(owner, Substitute.For<IBattle>());

        // Assert
        var damageCalls = owner.ReceivedCalls().Count(c => c.GetMethodInfo().Name == "Damage");
        await Assert.That(damageCalls).IsEqualTo(1);
    }

    /// <summary>
    /// Bulbapedia (Generation IV): the bound target "takes damage ... at the end of each turn"; this is
    /// indirect damage, not move damage, so it uses <see cref="DamageSource.Misc"/>.
    /// </summary>
    [Test]
    public async Task OnEndTurn_TrappedPokemon_DamageIsIndirect()
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(100);

        // Act
        effect.OnEndTurn(owner, Substitute.For<IBattle>());

        // Assert
        var call = owner.ReceivedCalls().First(c => c.GetMethodInfo().Name == "Damage");
        await Assert.That((DamageSource)call.GetArguments()[1]!).IsEqualTo(DamageSource.Misc);
    }

    /// <summary>
    /// Bulbapedia (Generation IV): "A bound target cannot switch out".
    /// </summary>
    [Test]
    public async Task PreventSelfSwitch_TrappedPokemon_CannotSwitchOut()
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(100);
        var choice = Substitute.For<ISwitchChoice>();
        choice.User.Returns(owner);
        var prevent = false;

        // Act
        effect.PreventSelfSwitch(choice, ref prevent);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia (Generation IV): "A bound target cannot switch out or flee".
    /// </summary>
    [Test]
    public async Task PreventSelfRunAway_TrappedPokemon_CannotFlee()
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(100);
        var choice = Substitute.For<IFleeChoice>();
        choice.User.Returns(owner);
        var prevent = false;

        // Act
        effect.PreventSelfRunAway(choice, ref prevent);

        // Assert
        await Assert.That(prevent).IsTrue();
    }

    /// <summary>
    /// Bulbapedia (Generations VI and VII): "Ghost-type Pokémon cannot be trapped by Magma Storm." A trapped
    /// Ghost-type Pokémon must remain free to switch out.
    /// </summary>
    [Test]
    public async Task PreventSelfSwitch_GhostTypeOwner_CanStillSwitchOut()
    {
        // Arrange
        var (effect, owner) = CreateTrappedPokemon(100);
        owner.Types.Returns(new List<TypeIdentifier> { new(8, "ghost") });
        var choice = Substitute.For<ISwitchChoice>();
        choice.User.Returns(owner);
        var prevent = false;

        // Act
        effect.PreventSelfSwitch(choice, ref prevent);

        // Assert
        await Assert.That(prevent).IsFalse();
    }

    /// <summary>
    /// Bulbapedia (Generations VI and VII): if the user is holding a Binding Band, the end-of-turn damage of
    /// Magma Storm is increased to 1/6 of the target's maximum HP.
    /// The damage change flows through the <see cref="CustomTriggers.ModifyBind"/> custom trigger; a script on
    /// the user that sets the damage to 1/6 results in end-of-turn damage of 1/6 max HP.
    /// </summary>
    [Test, Arguments(120u, 20u), Arguments(48u, 8u)]
    public async Task OnSecondaryEffect_DamageSetToOneSixthByTrigger_EndTurnDamageIsOneSixth(uint maxHealth,
        uint expectedDamage)
    {
        // Arrange
        var (script, move, target, targetVolatile) = CreateTestSetup(new ModifyBindTrigger(damagePercent: 1f / 6f));
        target.MaxHealth.Returns(maxHealth);

        // Act
        script.OnSecondaryEffect(move, target, 0);
        var effect = targetVolatile.Get<MagmaStormEffect>();
        await Assert.That(effect).IsNotNull();
        effect!.OnEndTurn(target, Substitute.For<IBattle>());

        // Assert
        await Assert.That(GetDamageAmount(target)!.Value).IsEqualTo(expectedDamage);
    }

    /// <summary>
    /// Bulbapedia (Generation V onwards): if the user is holding a Grip Claw, the trapping lasts seven turns.
    /// The duration change flows through the <see cref="CustomTriggers.ModifyBind"/> custom trigger; a script
    /// on the user that sets the duration to 7 results in an effect lasting 7 turns.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DurationSetToSevenByTrigger_EffectLastsSevenTurns()
    {
        // Arrange
        var (script, move, target, targetVolatile) = CreateTestSetup(new ModifyBindTrigger(7));
        target.MaxHealth.Returns(160u);

        // Act
        script.OnSecondaryEffect(move, target, 0);
        var effect = targetVolatile.Get<MagmaStormEffect>();
        await Assert.That(effect).IsNotNull();
        var turnsWithDamage = CountEndTurnDamageTicks(effect!, target);

        // Assert
        await Assert.That(turnsWithDamage).IsEqualTo(7);
    }

    /// <summary>
    /// Bulbapedia (Generation V onwards): the trapping lasts for four to five turns. After at most five
    /// end-of-turn ticks the trap must have removed itself from the target.
    /// </summary>
    [Test]
    public async Task OnEndTurn_AfterFiveEndOfTurns_TrapHasEnded()
    {
        // Arrange
        var (script, move, target, targetVolatile) = CreateTestSetup();
        target.MaxHealth.Returns(80u);
        script.OnSecondaryEffect(move, target, 0);
        var effect = targetVolatile.Get<MagmaStormEffect>()!;
        var battle = Substitute.For<IBattle>();

        // Act - five end-of-turn ticks, the maximum duration of the trap
        for (var i = 0; i < 5; i++)
            effect.OnEndTurn(target, battle);

        // Assert
        await Assert.That(targetVolatile.Contains("magma_storm")).IsFalse();
    }
}