refactored modifications

Assets/Scripts/Game/Ball.cs

@@ -1,6 +1,7 @@
 using System;
 using Unity.Netcode;
 using UnityEngine;
+using UnityEngine.Serialization;
 using Random = UnityEngine.Random;
 
 namespace Game {
@@ -9,6 +10,8 @@ namespace Game {
 
 		private CircleCollider2D Collider { get; set; }
 
+		public Player LastContactPlayer { get; set; }
+
 		public float Radius {
 			get => transform.localScale.x * Collider.radius;
 			set => transform.localScale = new Vector3(1, 1, 1) * value * 2;

Assets/Scripts/Game/GameManager.cs

@@ -52,7 +52,7 @@ namespace Game {
 			Assert.AreApproximatelyEqual(rs.y, 0.5f);
 		}
 
-		private void Start() {
+		private void Awake() {
 			Settings.Type = Type.Hybrid;
 			Settings.AIDifficulty = Difficulty.VeryHard;
 

Assets/Scripts/Game/Modification.cs

@@ -1,15 +1,55 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using Unity.Netcode;
 using UnityEngine;
+using UnityEngine.UIElements;
 
 namespace Game {
-	public class Modification : MonoBehaviour {
 
+	public enum ModType { Nerf, Buff }
+	public enum ModEffect { Speed, Border }
+	
+	public struct ModificationProperties {
+		public ModType Type { get; set; }
+		public ModEffect Effect { get; set; }
+
+		public float PickupDuration { get; set; }
+
+		public float ActiveDuration { get; set; }
 	}
 
-	public class SpeedModification : Modification {
+	public class ActiveModification {
+		public ModificationProperties Properties { get; set; }
+
+		public IEnumerator Process(VisualElement panel, List<ActiveModification> modifications) {
+			modifications.Add(this);
+			VisualElement element = GameUI.AddModification(panel, this);
 			
+			yield return new WaitForSeconds(Properties.ActiveDuration);
+			
+			element.RemoveFromHierarchy();
+			modifications.Remove(this);
+		}
 	}
 	
-	public class BorderModification : Modification {
+	public class Modification : NetworkBehaviour {
+
+		public ModificationProperties Properties { get; set; }
 
+		private IEnumerator Start() {
+			yield return new WaitForSeconds(Properties.PickupDuration);
+			Destroy(gameObject);
+		}
+
+		private void OnTriggerEnter2D(Collider2D other) {
+			Player p = other.GetComponent<Ball>().LastContactPlayer;
+			if (p != null) {
+				Destroy(gameObject);
+				ActiveModification mod = new() {Properties = Properties};
+				StartCoroutine(mod.Process(p.Panel, p.Modifications));
+			}
+		}
 	}
+
 }

Assets/Scripts/Game/Player.cs

@@ -1,7 +1,10 @@
 using System;
+using System.Collections;
+using System.Collections.Generic;
 using Unity.Netcode;
 using UnityEngine;
 using UnityEngine.InputSystem;
+using UnityEngine.UIElements;
 
 namespace Game {
 	
@@ -15,15 +18,16 @@ namespace Game {
 		
 		protected bool goingLeft, goingRight;
 
+		public VisualElement Panel { get; private set; }
+
+		public List<ActiveModification> Modifications { get; } = new();
+		
 		// Units per second
 		protected float Speed => 15;
 		
 		// Unit distance from zero
 		protected float Border => Dimensions.Singleton.Width / 2;
 
-		private SpeedModification speedModification;
-		private BorderModification borderModification;
-
 		protected float Width => transform.localScale.x;
 		
 		private float LeftEdge => X - Width / 2;
@@ -56,6 +60,11 @@ namespace Game {
 			transform.position = new Vector2(0, y);
 			if (Side == Side.Top)
 				transform.Rotate(transform.forward, 180);
+			Panel = GameUI.Singleton.PlayerPanel(Side);
+		}
+
+		private void OnCollisionEnter2D(Collision2D other) {
+			other.gameObject.GetComponent<Ball>().LastContactPlayer = this;
 		}
 	}
 	

Assets/Scripts/GameUI.cs

@@ -1,21 +1,51 @@
 using System;
+using System.Collections.Generic;
 using System.Linq;
+using Game;
 using UnityEngine;
+using UnityEngine.Assertions;
 using UnityEngine.UIElements;
 
 public class GameUI : MonoBehaviour {
 
 	private UIDocument document;
-	private void OnEnable() {
+	public static GameUI Singleton;
+	private void Awake() {
+		Singleton = this;
 		document = GetComponent<UIDocument>();
 		PreparePlayerPanels();
 	}
 	
+	private List<VisualElement> PlayerPanels => document.rootVisualElement.Children().Where(e => e.ClassListContains("player_panel")).ToList();
+
+	public VisualElement PlayerPanel(Side side) {
+		return side switch {
+			Side.Top => PlayerPanels[0],
+			Side.Bottom => PlayerPanels[1],
+			_ => throw new ArgumentOutOfRangeException(nameof(side), side, null)
+		};
+	}
+	
+	// TODO create correct visual element, attach it to panel with background-image and return it
+	public static VisualElement AddModification(VisualElement playerPanel, ActiveModification modification) {
+		VisualElement listElement = ModsList(playerPanel, modification.Properties.Type);
+		
+		return listElement;
+	}
+
+	private static VisualElement ModsList(VisualElement player, ModType type) {
+		return type switch {
+			ModType.Buff => player.Children().First(e => e.ClassListContains("mods_list")),
+			ModType.Nerf => player.Children().Last(e => e.ClassListContains("mods_list")),
+			_ => throw new ArgumentOutOfRangeException(nameof(type), type, null)
+		};
+	}
+
 	void PreparePlayerPanels() {
-		var players = document.rootVisualElement.Children().Where(e => e.ClassListContains("player_panel"));
+		var players = PlayerPanels;
+		Assert.AreEqual(players.Count, 2);
 
 		float heightPercentage = Dimensions.Singleton.panelHeightPercentage;
-		
 		foreach (var playerPanel in players)
 			playerPanel.style.height = Length.Percent(heightPercentage);
 	}

Assets/UI Toolkit/player_panel.uss

@@ -19,7 +19,7 @@ Button {
     margin-bottom: 5px;
 }
 
-.modification {
+.mods_list > VisualElement {
     width: 100%;
     flex-grow: 1;
     background-image: url('project://database/Packages/com.unity.2d.sprite/Editor/ObjectMenuCreation/DefaultAssets/Textures/HexagonFlat-Top.png?fileID=2747690628134850419&guid=16037dbd798344f57a526d53d48f5ead&type=3#Hexagon Flat-Top');