/* eslint-disable indent */

/**
 * Module for performing auto-focus.
 * @module components/autoFocuser
 */

import focusManager from 'focusManager';
import layoutManager from 'layoutManager';

    /**
     * Previously selected element.
     */
    let activeElement;

    /**
     * Returns _true_ if AutoFocuser is enabled.
     */
    export function isEnabled() {
        return layoutManager.tv;
    }

    /**
     * Start AutoFocuser.
     */
    export function enable() {
        if (!isEnabled()) {
            return;
        }

        window.addEventListener('focusin', function (e) {
            activeElement = e.target;
        });

        console.debug('AutoFocuser enabled');
    }

    /**
     * Set focus on a suitable element, taking into account the previously selected.
     * @param {HTMLElement} [container] - Element to limit scope.
     * @returns {HTMLElement} Focused element.
     */
    export function autoFocus(container) {
        if (!isEnabled()) {
            return null;
        }

        container = container || document.body;

        let candidates = [];

        if (activeElement) {
            // These elements are recreated
            if (activeElement.classList.contains('btnPreviousPage')) {
                candidates.push(container.querySelector('.btnPreviousPage'));
                candidates.push(container.querySelector('.btnNextPage'));
            } else if (activeElement.classList.contains('btnNextPage')) {
                candidates.push(container.querySelector('.btnNextPage'));
                candidates.push(container.querySelector('.btnPreviousPage'));
            } else if (activeElement.classList.contains('btnSelectView')) {
                candidates.push(container.querySelector('.btnSelectView'));
            }

            candidates.push(activeElement);
        }

        candidates = candidates.concat(Array.from(container.querySelectorAll('.btnResume')));
        candidates = candidates.concat(Array.from(container.querySelectorAll('.btnPlay')));

        let focusedElement;

        candidates.every(function (element) {
            if (focusManager.isCurrentlyFocusable(element)) {
                focusManager.focus(element);
                focusedElement = element;
                return false;
            }

            return true;
        });

        if (!focusedElement) {
            // FIXME: Multiple itemsContainers
            const itemsContainer = container.querySelector('.itemsContainer');

            if (itemsContainer) {
                focusedElement = focusManager.autoFocus(itemsContainer);
            }
        }

        if (!focusedElement) {
            focusedElement = focusManager.autoFocus(container);
        }

        return focusedElement;
    }

/* eslint-enable indent */

export default {
    isEnabled: isEnabled,
    enable: enable,
    autoFocus: autoFocus
};