/**
 * Timed singleton generator.
 *
 * The `TimedSingleton` is a type of {@link Singleton} class who re-constructs the singleton
 * value repeatedly whenever specific time has been elapsed after the last lazy construction.
 *
 * @template T Type of the value to be lazy-constructed
 * @author Jeongho Nam - https://github.com/samchon
 */
export class TimedSingleton<T, Args extends any[] = []> {
    private readonly interval_: number;
    private readonly closure_: (...args: Args) => T;
    private expired_at_: number;
    private value_: T;

    /**
     * Initializer Constructor.
     *
     * @param interval Specific interval time, to determine whether re-generation of the singleton value is required or not, as milliseconds
     * @param closure Lazy constructor function returning the target value
     */
    public constructor(interval: number, closure: (...args: Args) => T) {
        this.interval_ = interval;
        this.closure_ = closure;
        this.value_ = null!;
        this.expired_at_ = 0;
    }

    /**
     * Get value.
     *
     * @returns The lazy constructed value
     */
    public get(...args: Args): T {
        if (Date.now() >= this.expired_at_) {
            this.expired_at_ = Date.now() + this.interval_;
            this.value_ = this.closure_(...args);
        }
        return this.value_;
    }
}