import * as sfw from 'sfw';
const { Div, Img } = sfw.element.native;

import Month from '../../month.js';

import Image from '../../widgets/image/index.js';

const css = await sfw.css(import.meta.url, './index.css')

export default class ImageViewer extends sfw.element.Container {
	#container
	#subtitle
	#images
	#current_month

	constructor() {
		super({ css });

		this.#current_month = null;

		this.#images = [];

		this.body.append(
			this.#container = Div.new({
				id: 'container',
				onscroll: () => this.preload_all(),
				children: [
					this.#subtitle = Div.new({
						id: 'subtitle',
						innerHTML: 'Powered by <i>Memora<i>'
					})
				],
			})
		);
	}

	add(metadata) {
		const month = Month.from_unix(metadata.timestamp);

		if (month != this.#current_month && !(month?.is_same(this.#current_month))) {
			const content = month == null ? 'No Date' : `${month.name} ${month.year}`;
			this.#current_month = month;
			const title = Div.new({
				id: 'date',
				innerText: content,
			})
			this.#container.insertBefore(title, this.#subtitle);
		}

		const image = Image.new({ metadata });
		this.#images.push(image);
		this.#container.insertBefore(image, this.#subtitle);
	}

	clear() {
		this.#container.innerHTML = '';
		this.#container.append(this.#subtitle);
	}

	jump_to(month) {
		const image = this.#images.find(i => i.month == month || i.month.is_same(month));
		image.scrollIntoView({ behavior: 'instant' })
	}

	preload_all() {
		this.#images.forEach(image => this.#preload(image))
	}

	#preload(image) {
		const loading_zone_after = (this.#container.scrollTop + this.#container.offsetHeight) * 2;
		const loading_zone_before = this.#container.scrollTop - image.offsetHeight * 2;

		if (loading_zone_before < image.offsetTop && image.offsetTop < loading_zone_after) {
			image.load();
		}
	}
}