import { ValueInspector } from '../../io/index.js';
import type { Answerable } from '../Answerable.js';
import { Question } from '../Question.js';
import type { AnswersQuestions } from '../questions/index.js';
import { Ability } from './Ability.js';
import type { UsesAbilities } from './UsesAbilities.js';

/**
 * This [`Ability`](https://serenity-js.org/api/core/class/Ability/) enables an [`Actor`](https://serenity-js.org/api/core/class/Actor/) to resolve the value of a given [`Answerable`](https://serenity-js.org/api/core/#Answerable).
 *
 * `AnswerQuestions` is used internally by [`Actor.answer`](https://serenity-js.org/api/core/class/Actor/#answer), and it is unlikely you'll ever need to use it directly in your code.
 * That is, unless you're building a custom Serenity/JS extension and want to override the default behaviour of the framework,
 * in which case you should check out the [Contributor's Guide](https://serenity-js.org/community/contributing/).
 *
 * @group Abilities
 */
export class AnswerQuestions extends Ability {
    constructor(protected readonly actor: AnswersQuestions & UsesAbilities) {
        super();
    }

    answer<T>(answerable: Answerable<T>): Promise<T> {

        if (AnswerQuestions.isDefined(answerable) && ValueInspector.isPromise(answerable)) {
            return answerable;
        }

        if (AnswerQuestions.isDefined(answerable) && Question.isAQuestion(answerable)) {
            return this.answer(answerable.answeredBy(this.actor));
        }

        return Promise.resolve(answerable as T);
    }

    private static isDefined<V>(v: Answerable<V>) {
        return !(v === undefined || v === null);
    }
}