import { Injectable, signal } from '@angular/core';

const MIN_LOADING_TIME = 300;

export interface ILoadingConfig {
    readonly type: 'spinner' | 'progress-bar';
    readonly title?: string;
    readonly value?: number;
    readonly remainingTime?: string;
}

@Injectable()
export class LoadingService {
    readonly #loading = signal<ILoadingConfig | undefined>(undefined);
    readonly isLoading = this.#loading.asReadonly();
    #loadingStarted = 0;
    #stopTimeout: NodeJS.Timeout | undefined;

    start(config: ILoadingConfig = { type: 'spinner' }): void {
        if (this.#stopTimeout) {
            clearTimeout(this.#stopTimeout);
            this.#stopTimeout = undefined;
        }
        setTimeout(() => {
            this.#loading.set(config);
            this.#loadingStarted = Date.now();
        });
    }

    update(config: ILoadingConfig): void {
        if (!this.isLoading()) {
            return this.start(config);
        }
        this.#loading.set(config);
    }

    stop(): void {
        const timeSinceStarted = new Date().getTime() - this.#loadingStarted;
        const remainingLoadingTime = MIN_LOADING_TIME - timeSinceStarted;

        return remainingLoadingTime > 0 ? this.#stopAfter(remainingLoadingTime) : this.#stop();
    }

    loadWhile(func: Promise<unknown>): void {
        this.start();

        func.then(
            () => this.stop(),
            () => this.stop(),
        );
    }

    #stop(): void {
        setTimeout(() => this.#loading.set(undefined));
    }

    #stopAfter(clearAfter: number): void {
        this.#stopTimeout = setTimeout(() => this.#stop(), clearAfter);
    }
}