oecs-sharp/Game.Blackjack.Tests/GameFlowTests.cs

using FluentAssertions;
using Game.Blackjack;
using OECS;
using Xunit;

namespace Game.Blackjack.Tests;

public class GameFlowTests
{
    [Fact]
    public void NewGame_StartsInBettingPhase()
    {
        var (world, _) = TestHelpers.SetupGame();

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.Betting);
        state.Chips.Should().Be(100);
        state.RoundNumber.Should().Be(1);
    }

    [Fact]
    public void PlaceBet_AdvancesToDealing()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.PlayerTurn);
        state.CurrentBet.Should().Be(10);
        state.Chips.Should().Be(90);
    }

    [Fact]
    public void PlaceBet_RejectsInsufficientChips()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 200 });
        group.RunLogical();

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.Betting);
        state.Chips.Should().Be(100);
    }

    [Fact]
    public void PlaceBet_RejectsZeroOrNegative()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 0 });
        group.RunLogical();
        world.ReadSingleton<GameState>().Phase.Should().Be(GamePhase.Betting);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = -5 });
        group.RunLogical();
        world.ReadSingleton<GameState>().Phase.Should().Be(GamePhase.Betting);
    }

    [Fact]
    public void Dealing_CreatesDeckAndHands()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        TestHelpers.FindEntity<Deck>(world).Should().NotBe(Entity.Null);
        TestHelpers.FindEntity<PlayerHand>(world).Should().NotBe(Entity.Null);
        TestHelpers.FindEntity<DealerHand>(world).Should().NotBe(Entity.Null);
    }

    [Fact]
    public void Dealing_DealsTwoCardsToEach()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        var playerHand = TestHelpers.FindEntity<PlayerHand>(world);
        var dealerHand = TestHelpers.FindEntity<DealerHand>(world);

        TestHelpers.CountCardsInHand(world, playerHand).Should().Be(2);
        TestHelpers.CountCardsInHand(world, dealerHand).Should().Be(2);
    }

    [Fact]
    public void Hit_DrawsOneCard()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        var playerHand = TestHelpers.FindEntity<PlayerHand>(world);
        var before = TestHelpers.CountCardsInHand(world, playerHand);

        world.Commands.Enqueue(new HitCommand());
        group.RunLogical();

        var after = TestHelpers.CountCardsInHand(world, playerHand);
        after.Should().Be(before + 1);
    }

    [Fact]
    public void Stand_AdvancesToDealerTurn()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        world.Commands.Enqueue(new StandCommand());
        group.RunLogical();

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.RoundOver);
    }

    [Fact]
    public void NewRound_ResetsPhase()
    {
        var (world, group) = TestHelpers.SetupGame();

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();
        world.Commands.Enqueue(new StandCommand());
        group.RunLogical();

        world.Commands.Enqueue(new NewRoundCommand());
        group.RunLogical();

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.Betting);
        state.Result.Should().Be(RoundResult.None);
    }

    [Fact]
    public void DeterministicSeed_ProducesSameDeal()
    {
        var (world1, group1) = TestHelpers.SetupGame(seed: 42);
        world1.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group1.RunLogical();
        var cards1 = TestHelpers.GetAllCards(world1);

        var (world2, group2) = TestHelpers.SetupGame(seed: 42);
        world2.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group2.RunLogical();
        var cards2 = TestHelpers.GetAllCards(world2);

        cards1.Should().Equal(cards2);
    }

    [Fact]
    public void PlayerBust_LosesBet()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 12345);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        while (world.ReadSingleton<GameState>().Phase == GamePhase.PlayerTurn)
        {
            world.Commands.Enqueue(new HitCommand());
            group.RunLogical();
        }

        var state = world.ReadSingleton<GameState>();
        state.Phase.Should().Be(GamePhase.RoundOver);
    }

    [Fact]
    public void Serialization_RoundTrips()
    {
        var (world, group) = TestHelpers.SetupGame(seed: 42);

        world.Commands.Enqueue(new PlaceBetCommand { Amount = 10 });
        group.RunLogical();

        using var stream = new MemoryStream();
        WorldSerializer.Save(world, stream);
        stream.Position = 0;

        var world2 = new World();
        WorldSerializer.Load(world2, stream);

        var state = world2.ReadSingleton<GameState>();
        state.Chips.Should().Be(90);
        state.CurrentBet.Should().Be(10);
        state.RoundNumber.Should().Be(1);
    }
}