import { effectScope, type EffectScope } from "vue";

/**
* Creates a constructor for a class that may contain vue reactive primitives, setting up an effect scope to capture
* all effects, assigning a destroy function that will stop the effect scope and clean up effects.
*
* Wrapped classes containing reactive effects can be easily used without tying their lifetimes to a component instance
* or the global application. This is effectively the equivalent of heap allocation instead of stack allocation.
*
* Advantages:
* - less boilerplate (no need to remember to return all public methods and properties from a composable)
* - makes it possible to manange reactive lifetimes that are entirely independent of UI state, such as objects that
*   are constantly instantiated and destroyed that manage their own reactive states, that need to be referenced
*   globally by multiple parts of a complex UI.
* - The class syntax makes it easy to reference properites and functions before their declaration, avoiding annoying
*   forward declarations.
*/
export default class EffectScoped {
    private effectScope?: EffectScope;

    /**
     * Creates an effectscoped version of the class
     */
    static asScoped<C extends new(...args: any[]) => EffectScoped>(this: C, ...args: ConstructorParameters<C>): InstanceType<C> {
        const scope = effectScope(true);
        const instance = scope.run(() => new this(...args)) ?? null;
        if (instance === null) {
            throw new Error(`Failed to instantiate class ${ this.constructor.name }.`);
        }
        instance.effectScope = scope;
        return instance as InstanceType<C>;
    }

    onDestroy() {}

    destroy() {
        this.onDestroy();
        this.effectScope?.stop();
    }
}