GameJamDungeon/src/enemy/Enemy.cs

using Chickensoft.AutoInject;
using Chickensoft.Collections;
using Chickensoft.GodotNodeInterfaces;
using Chickensoft.Introspection;
using Godot;
using System;
using System.Linq;

namespace GameJamDungeon;

public interface IEnemy : ICharacterBody3D
{
  public IEnemyLogic EnemyLogic { get; }

  public AutoProp<double> CurrentHP { get; set; }

  public EnemyStatInfo EnemyStatInfo { get; set; }

  public NavigationAgent3D NavAgent { get; set; }
}

[Meta(typeof(IAutoNode))]
public partial class Enemy : CharacterBody3D, IEnemy, IProvide<IEnemyLogic>
{
  public override void _Notification(int what) => this.Notify(what);

  public IEnemyLogic EnemyLogic { get; set; } = default!;

  IEnemyLogic IProvide<IEnemyLogic>.Value() => EnemyLogic;

  public EnemyLogic.IBinding EnemyBinding { get; set; } = default!;

  [Dependency] IGameRepo GameRepo => this.DependOn<IGameRepo>();

  [Export]
  public EnemyStatInfo EnemyStatInfo { get; set; } = new();

  public static PackedScene CollisionDetectorScene => GD.Load<PackedScene>("res://src/enemy/CollisionDetector.tscn");

  public static Area3D CollisionDetector { get; set; } = default!;

  public AutoProp<double> CurrentHP { get; set; }

  [Node] public NavigationAgent3D NavAgent { get; set; } = default!;

  public void Setup()
  {
    EnemyLogic = new EnemyLogic();
    EnemyLogic.Set(EnemyStatInfo);
    EnemyLogic.Set(this as IEnemy);
    EnemyLogic.Set(GameRepo);
  }

  public void Initialize()
  {
    CurrentHP = new AutoProp<double>(EnemyStatInfo.MaximumHP);
    CurrentHP.Sync += OnHPChanged;
  }

  public void OnResolved()
  {
    EnemyBinding = EnemyLogic.Bind();

    EnemyBinding
      .Handle((in EnemyLogic.Output.MovementComputed output) =>
      {
        var spriteNode = GetChildren().OfType<AnimatedSprite3D>();

        if (spriteNode.Any())
          PlayMovementAnimations(spriteNode.Single(), Velocity);

        MoveAndCollide(output.Velocity);
      })
      .Handle((in EnemyLogic.Output.Die output) =>
      {
        QueueFree();
      })
      .Handle((in EnemyLogic.Output.HitByPlayer output) =>
      {
      });

    this.Provide();

    EnemyLogic.Start();
  }

  public void PlayMovementAnimations(AnimatedSprite3D sprite, Vector3 velocity)
  {
    if (sprite != null && velocity.Length() > 0.2f)
    {
      var lookdir = (GlobalPosition).Normalized();
      var sign = lookdir.Sign();
      if (lookdir.MaxAxisIndex() == Vector3.Axis.X && sign.X == 1)
        sprite.Play("walk_right");
      if (lookdir.MaxAxisIndex() == Vector3.Axis.X && sign.X == -1)
        sprite.Play("walk_left");
      if (lookdir.MaxAxisIndex() == Vector3.Axis.Z && sign.Z == 1)
        sprite.Play("walk_forward");
      if (lookdir.MaxAxisIndex() == Vector3.Axis.Z && sign.Z == -1)
        sprite.Play("walk_backward");
    }
    if (sprite != null && velocity.IsZeroApprox())
      sprite.Stop();
  }


  public void OnPhysicsProcess(double delta)
  {
    EnemyLogic.Input(new EnemyLogic.Input.PhysicsTick(delta));
  }

  public void OnPlayerHitboxEntered(Area3D body)
  {
    if (body is IHitbox hitBox)
    {
      if (CurrentHP.Value > 0)
      {
        var damage = DamageCalculator.CalculatePlayerDamage(hitBox.Damage, hitBox.GetParent<IPlayer>().PlayerStatInfo, EnemyStatInfo);
        GD.Print($"Enemy Hit for {damage} damage.");
        EnemyLogic.Input(new EnemyLogic.Input.HitByPlayer(damage));
      }
    }
  }

  private void OnHPChanged(double newHP)
  {
    if (newHP <= 0)
      EnemyLogic.Input(new EnemyLogic.Input.Killed());
  }

  public void OnReady()
  {
    SetPhysicsProcess(true);
    CollisionDetector = CollisionDetectorScene.Instantiate<Area3D>();
    CollisionDetector.AreaEntered += OnPlayerHitboxEntered;
    AddChild(CollisionDetector);
  }

  public void OnExitTree()
  {
    EnemyLogic.Stop();
    EnemyBinding.Dispose();
  }
}