feat: initial import

Game/TargetSpawner.cs

@@ -0,0 +1,61 @@
+using System.Collections.Generic;
+using Godot;
+using GodotHostTest.Helpers;
+using GodotHostTest.Interfaces;
+using R3;
+
+namespace GodotHostTest.Game;
+
+public partial class TargetSpawner : Node2D, ITargetCollector, ITargetSpawner
+{
+    [Export] public double TimeBetweenSpawns;
+
+    [Export] public required Timer Timer;
+
+    private readonly List<ITarget> _availableTargets = [];
+
+    public override void _Ready()
+    {
+        Spawn();
+        Timer.Start(TimeBetweenSpawns);
+    }
+
+    private void MakeTargetAvailable(ITarget target)
+    {
+        _availableTargets.Add(target);
+    }
+
+    private void OnTimer()
+    {
+        Spawn();
+    }
+
+    private void Spawn()
+    {
+        // pick a random target
+        var randomIndex = GD.RandRange(0, _availableTargets.Count - 1);
+        var target = _availableTargets[randomIndex];
+        _availableTargets.RemoveAt(randomIndex);
+
+        // enable it
+        target.Enable();
+
+        // notify that a target has been spawned
+        _targetSpawned.OnNext(target);
+    }
+
+    public void NewTarget(ITarget target)
+    {
+        _availableTargets.Add(target);
+        target.Hit.Merge(target.TimedOut).Select(_ => target).Subscribe(MakeTargetAvailable).AddTo(this);
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        base.Dispose(disposing);
+        _targetSpawned.Dispose();
+    }
+
+    private readonly Subject<ITarget> _targetSpawned = new();
+    public Observable<ITarget> TargetSpawned => _targetSpawned.AsObservable();
+}