Slash-The-Hordes/assets/Scripts/Game/Unit/Enemy/EnemySpawner.ts

import { Component, Node, Prefab, Vec3, _decorator } from "cc";
import { ISignal } from "../../../Services/EventSystem/ISignal";
import { Signal } from "../../../Services/EventSystem/Signal";
import { ObjectPool } from "../../../Services/ObjectPool";

import { Enemy } from "./Enemy";
const { ccclass, property } = _decorator;

@ccclass("EnemySpawner")
export class EnemySpawner extends Component {
    @property(Prefab) private enemies: Prefab[] = [];

    public enemyAddedEvent: Signal<Enemy> = new Signal<Enemy>();
    public enemyRemovedEvent: Signal<Enemy> = new Signal<Enemy>();

    private enemyPool: ObjectPool<Enemy>;

    private targetNode: Node;

    public init(targetNode: Node): void {
        this.targetNode = targetNode;
        this.enemyPool = new ObjectPool(this.enemies[0], this.node, 50, "Enemy");
    }

    public get EnemyAddedEvent(): ISignal<Enemy> {
        return this.enemyAddedEvent;
    }

    public get EnemyRemovedEvent(): ISignal<Enemy> {
        return this.enemyRemovedEvent;
    }

    public spawnNewEnemy(positionX: number, positionY: number): void {
        const enemy = this.enemyPool.borrow();
        const spawnPosition = new Vec3();
        spawnPosition.x = this.targetNode.worldPosition.x + positionX;
        spawnPosition.y = this.targetNode.worldPosition.y + positionY;
        enemy.setup(spawnPosition);

        enemy.DeathEvent.on(this.returnEnemyToPool, this);

        this.enemyAddedEvent.trigger(enemy);
    }

    private returnEnemyToPool(enemy: Enemy): void {
        enemy.DeathEvent.off(this.returnEnemyToPool);
        this.enemyPool.return(enemy);

        this.enemyRemovedEvent.trigger(enemy);
    }
}