using GameCli;
using Xunit;

namespace GameCli.Tests;

public class ObservationTests
{
    [Fact]
    public void Build_HasSevenDimensions()
    {
        var ship = new ShipState(0.5f, 0.5f, 0f, 0f, 0f, 0f);
        var obs = Observation.Build(ship, target: (0.5f, 0.5f));
        Assert.Equal(7, obs.Length);
    }

    [Fact]
    public void Build_DisplacementIsTargetMinusShip()
    {
        var ship = new ShipState(0.3f, 0.4f, 0f, 0f, 0f, 0f);
        var obs = Observation.Build(ship, target: (0.7f, 0.9f));
        // dx, dy at indices 0, 1
        Assert.Equal(0.4f, obs[0], precision: 5);
        Assert.Equal(0.5f, obs[1], precision: 5);
    }

    [Fact]
    public void Build_EncodesVelocity()
    {
        var ship = new ShipState(0.5f, 0.5f, 0.1f, -0.2f, 0f, 0f);
        var obs = Observation.Build(ship, target: (0.5f, 0.5f));
        Assert.Equal(0.1f,  obs[2], precision: 5);
        Assert.Equal(-0.2f, obs[3], precision: 5);
    }

    [Fact]
    public void Build_EncodesAngleAsSinCos()
    {
        var ship = new ShipState(0.5f, 0.5f, 0f, 0f, MathF.PI / 2f, 0f);
        var obs = Observation.Build(ship, target: (0.5f, 0.5f));
        // sin(π/2)=1, cos(π/2)=0
        Assert.Equal(1f, obs[4], precision: 5);
        Assert.Equal(0f, obs[5], precision: 5);
    }

    [Fact]
    public void Build_LastDimIsAngularVelocity()
    {
        var ship = new ShipState(0.5f, 0.5f, 0f, 0f, 0f, 0.7f);
        var obs = Observation.Build(ship, target: (0.5f, 0.5f));
        Assert.Equal(0.7f, obs[6], precision: 5);
    }
}