import { _decorator, Component } from 'cc';
const { ccclass, property } = _decorator;

@ccclass('SingletonBase')
export abstract class SingletonBase<T extends Component> extends Component {
    private static _instance: any = null;

    public static getInstance<T extends Component>(this: new () => T): T {
        if ((this as any)._instance === null) {
            return null
        }
        return (this as any)._instance;
    }

    protected onLoad(): void {
        if ((this.constructor as any)._instance) {
            this.node.destroy();
            return;
        }
        (this.constructor as any)._instance = this;
    }

    protected onDestroy(): void {
        if ((this.constructor as any)._instance === this) {
            (this.constructor as any)._instance = null;
        }
    }
}