using PkmnLib.Dynamic.Models;
using PkmnLib.Plugin.Gen7.Scripts.Moves;
using PkmnLib.Static;

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

/// <summary>
/// Tests for the <see cref="FlameBurst"/> move script.
/// Gen V–VII Bulbapedia behavior: "Flame Burst deals damage to the target, then inflicts damage to up to two
/// Pokémon adjacent to that target (including the user if targeting an ally) equal to 1/16 of their
/// respective maximum HP." The splash damage is classified as effect damage rather than move damage.
/// </summary>
public class FlameBurstTests
{
    /// <summary>
    /// Creates a mocked battle Pokémon that lives in <paramref name="battle"/> on the given side and position.
    /// </summary>
    private static IBattlePokemon CreateBattlePokemon(IBattle battle, byte sideIndex, byte position, uint maxHp = 100)
    {
        var pokemon = Substitute.For<IBattlePokemon>();
        pokemon.Battle.Returns(battle);
        pokemon.SideIndex.Returns(sideIndex);
        pokemon.Position.Returns(position);
        pokemon.BoostedStats.Returns(new StatisticSet<uint>(maxHp, 0, 0, 0, 0, 0));
        pokemon.MaxHealth.Returns(maxHp);
        return pokemon;
    }

    /// <summary>
    /// Configures the two sides of <paramref name="battle"/> with the given Pokémon lists.
    /// </summary>
    private static void SetSides(IBattle battle, List<IBattlePokemon?> side0Pokemon, List<IBattlePokemon?> side1Pokemon)
    {
        var side0 = Substitute.For<IBattleSide>();
        side0.Pokemon.Returns(side0Pokemon);
        var side1 = Substitute.For<IBattleSide>();
        side1.Pokemon.Returns(side1Pokemon);
        battle.Sides.Returns(new[] { side0, side1 });
    }

    /// <summary>
    /// Creates a fully mocked double battle: the user and its ally on side 0, the target and its ally on
    /// side 1. Flame Burst is used by the user against the target.
    /// </summary>
    private static (FlameBurst script, IExecutingMove move, IBattlePokemon user, IBattlePokemon userAlly, IBattlePokemon
        target, IBattlePokemon targetAlly) CreateDoubleBattleSetup(uint targetAllyMaxHp = 160)
    {
        var script = new FlameBurst();
        var battle = Substitute.For<IBattle>();
        battle.PositionsPerSide.Returns((byte)2);

        var user = CreateBattlePokemon(battle, 0, 0);
        var userAlly = CreateBattlePokemon(battle, 0, 1);
        var target = CreateBattlePokemon(battle, 1, 0);
        var targetAlly = CreateBattlePokemon(battle, 1, 1, targetAllyMaxHp);
        SetSides(battle, [user, userAlly], [target, targetAlly]);

        var move = Substitute.For<IExecutingMove>();
        move.User.Returns(user);

        return (script, move, user, userAlly, target, targetAlly);
    }

    /// <summary>
    /// Helper to extract the damage amount from a Pokémon's received Damage calls, or 0 if none was received.
    /// </summary>
    private static uint GetDamageAmount(IBattlePokemon pokemon)
    {
        var call = pokemon.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "Damage");
        return call != null ? (uint)call.GetArguments()[0]! : 0;
    }

    /// <summary>
    /// Helper to extract the damage source from a Pokémon's received Damage calls.
    /// </summary>
    private static DamageSource? GetDamageSource(IBattlePokemon pokemon)
    {
        var call = pokemon.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "Damage");
        return call != null ? (DamageSource)call.GetArguments()[1]! : null;
    }

    /// <summary>
    /// Helper that checks whether a Pokémon received any Damage call.
    /// </summary>
    private static bool WasDamaged(IBattlePokemon pokemon) =>
        pokemon.ReceivedCalls().Any(c => c.GetMethodInfo().Name == "Damage");

    /// <summary>
    /// Bulbapedia: "Flame Burst deals damage to the target, then inflicts damage to up to two Pokémon adjacent
    /// to that target ... equal to 1/16 of their respective maximum HP."
    /// In a double battle, the target's ally is adjacent to the target and takes 1/16 of its own maximum HP.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DoubleBattle_TargetAllyTakesOneSixteenthOfItsMaxHp()
    {
        // Arrange
        var (script, move, _, _, target, targetAlly) = CreateDoubleBattleSetup(160);

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

        // Assert - 160 / 16 = 10
        await Assert.That(GetDamageAmount(targetAlly)).IsEqualTo(10u);
    }

    /// <summary>
    /// Bulbapedia: the splash damage is "equal to 1/16 of their respective maximum HP".
    /// Tests various maximum HP values to ensure proper integer truncation.
    /// </summary>
    [Test, Arguments(160u, 10u), Arguments(100u, 6u), Arguments(32u, 2u), Arguments(15u, 0u)]
    public async Task OnSecondaryEffect_DoubleBattle_SplashDamageCalculation(uint allyMaxHp, uint expectedDamage)
    {
        // Arrange
        var (script, move, _, _, target, targetAlly) = CreateDoubleBattleSetup(allyMaxHp);

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

        // Assert
        await Assert.That(GetDamageAmount(targetAlly)).IsEqualTo(expectedDamage);
    }

    /// <summary>
    /// Bulbapedia: the splash damage hits Pokémon "adjacent to that target". The user's own ally is not
    /// adjacent to the target and must not be damaged when targeting an opponent.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DoubleBattle_UserAllyIsNotDamaged()
    {
        // Arrange
        var (script, move, _, userAlly, target, _) = CreateDoubleBattleSetup();

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

        // Assert
        await Assert.That(WasDamaged(userAlly)).IsFalse();
    }

    /// <summary>
    /// Bulbapedia: "this extra damage is classified as effect damage", so the splash damage is dealt with
    /// <see cref="DamageSource.Misc"/> rather than move damage.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_DoubleBattle_SplashDamageUsesMiscDamageSource()
    {
        // Arrange
        var (script, move, _, _, target, targetAlly) = CreateDoubleBattleSetup();

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

        // Assert
        await Assert.That(GetDamageSource(targetAlly)!.Value).IsEqualTo(DamageSource.Misc);
    }

    /// <summary>
    /// Bulbapedia: "inflicts damage to up to two Pokémon adjacent to that target".
    /// In a triple battle with the target in the middle, both of the target's allies are adjacent and both
    /// take splash damage.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_TripleBattleTargetInMiddle_BothAdjacentAlliesDamaged()
    {
        // Arrange
        var script = new FlameBurst();
        var battle = Substitute.For<IBattle>();
        battle.PositionsPerSide.Returns((byte)3);

        var user = CreateBattlePokemon(battle, 0, 1);
        var target = CreateBattlePokemon(battle, 1, 1);
        var allyLeft = CreateBattlePokemon(battle, 1, 0, 96);
        var allyRight = CreateBattlePokemon(battle, 1, 2, 64);
        SetSides(battle, [null, user, null], [allyLeft, target, allyRight]);

        var move = Substitute.For<IExecutingMove>();
        move.User.Returns(user);

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

        // Assert - 96 / 16 = 6 and 64 / 16 = 4
        await Assert.That(GetDamageAmount(allyLeft)).IsEqualTo(6u);
        await Assert.That(GetDamageAmount(allyRight)).IsEqualTo(4u);
    }

    /// <summary>
    /// Bulbapedia: only Pokémon "adjacent to that target" take splash damage.
    /// In a triple battle with the target at the edge, the ally two positions away is not adjacent and takes
    /// no damage.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_TripleBattleTargetAtEdge_NonAdjacentAllyNotDamaged()
    {
        // Arrange
        var script = new FlameBurst();
        var battle = Substitute.For<IBattle>();
        battle.PositionsPerSide.Returns((byte)3);

        var user = CreateBattlePokemon(battle, 0, 0);
        var target = CreateBattlePokemon(battle, 1, 0);
        var allyMiddle = CreateBattlePokemon(battle, 1, 1, 160);
        var allyFar = CreateBattlePokemon(battle, 1, 2, 160);
        SetSides(battle, [user, null, null], [target, allyMiddle, allyFar]);

        var move = Substitute.For<IExecutingMove>();
        move.User.Returns(user);

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

        // Assert - only the adjacent ally is hit
        await Assert.That(GetDamageAmount(allyMiddle)).IsEqualTo(10u);
        await Assert.That(WasDamaged(allyFar)).IsFalse();
    }

    /// <summary>
    /// Bulbapedia: the splash damage hits Pokémon "adjacent to that target". In a single battle there are no
    /// Pokémon adjacent to the target, so nothing else is damaged.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_SingleBattle_NoSplashDamage()
    {
        // Arrange
        var script = new FlameBurst();
        var battle = Substitute.For<IBattle>();
        battle.PositionsPerSide.Returns((byte)1);

        var user = CreateBattlePokemon(battle, 0, 0);
        var target = CreateBattlePokemon(battle, 1, 0);
        SetSides(battle, [user], [target]);

        var move = Substitute.For<IExecutingMove>();
        move.User.Returns(user);

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

        // Assert - neither the user nor the target receives effect damage
        await Assert.That(WasDamaged(user)).IsFalse();
        await Assert.That(WasDamaged(target)).IsFalse();
    }

    /// <summary>
    /// Technical test: an empty adjacent position (a fainted or absent ally) does not cause an exception and
    /// simply receives no splash damage.
    /// </summary>
    [Test]
    public async Task OnSecondaryEffect_AdjacentPositionEmpty_DoesNotThrow()
    {
        // Arrange
        var script = new FlameBurst();
        var battle = Substitute.For<IBattle>();
        battle.PositionsPerSide.Returns((byte)2);

        var user = CreateBattlePokemon(battle, 0, 0);
        var userAlly = CreateBattlePokemon(battle, 0, 1);
        var target = CreateBattlePokemon(battle, 1, 0);
        SetSides(battle, [user, userAlly], [target, null]);

        var move = Substitute.For<IExecutingMove>();
        move.User.Returns(user);

        // Act & Assert
        await Assert.That(() => script.OnSecondaryEffect(move, target, 0)).ThrowsNothing();
    }
}