import FocusEvent from '../../event/events/FocusEvent.js';
import * as PropertySymbol from '../../PropertySymbol.js';
import IHTMLElement from '../html-element/IHTMLElement.js';
import ISVGElement from '../svg-element/ISVGElement.js';

/**
 * HTMLElement utility.
 */
export default class HTMLElementUtility {
	/**
	 * Triggers a blur event.
	 *
	 * @param element Element.
	 */
	public static blur(element: IHTMLElement | ISVGElement): void {
		if (
			element[PropertySymbol.ownerDocument][PropertySymbol.activeElement] !== element ||
			!element[PropertySymbol.isConnected]
		) {
			return;
		}

		const relatedTarget =
			element[PropertySymbol.ownerDocument][PropertySymbol.nextActiveElement] ?? null;

		element[PropertySymbol.ownerDocument][PropertySymbol.activeElement] = null;

		element.dispatchEvent(
			new FocusEvent('blur', {
				relatedTarget,
				bubbles: false,
				composed: true
			})
		);
		element.dispatchEvent(
			new FocusEvent('focusout', {
				relatedTarget,
				bubbles: true,
				composed: true
			})
		);
	}

	/**
	 * Triggers a focus event.
	 *
	 * @param element Element.
	 */
	public static focus(element: IHTMLElement | ISVGElement): void {
		if (
			element[PropertySymbol.ownerDocument][PropertySymbol.activeElement] === element ||
			!element[PropertySymbol.isConnected]
		) {
			return;
		}

		// Set the next active element so `blur` can use it for `relatedTarget`.
		element[PropertySymbol.ownerDocument][PropertySymbol.nextActiveElement] = element;

		const relatedTarget = element[PropertySymbol.ownerDocument][PropertySymbol.activeElement];

		if (element[PropertySymbol.ownerDocument][PropertySymbol.activeElement] !== null) {
			element[PropertySymbol.ownerDocument][PropertySymbol.activeElement].blur();
		}

		// Clean up after blur, so it does not affect next blur call.
		element[PropertySymbol.ownerDocument][PropertySymbol.nextActiveElement] = null;

		element[PropertySymbol.ownerDocument][PropertySymbol.activeElement] = element;

		element.dispatchEvent(
			new FocusEvent('focus', {
				relatedTarget,
				bubbles: false,
				composed: true
			})
		);
		element.dispatchEvent(
			new FocusEvent('focusin', {
				relatedTarget,
				bubbles: true,
				composed: true
			})
		);
	}
}