if (! Array.from) {
    Array.from = object => {
        'use strict';

        return [].slice.call(object);
    };
}

if (! Array.isArray) {
    Array.isArray = arg => Object.prototype.toString.call(arg) === '[object Array]';
}

// --- Constants ---
const arrayFrom = Array.from;

export const isArray = Array.isArray;

export const keyCodes = {
    ESC: 27,
    LEFT: 37,
    UP: 38,
    RIGHT: 39,
    DOWN: 40
};

// --- Dom Utils ---

// Returns true if the parent element contains the child element
const contains = (parent, child) => {
    if (! parent || typeof parent.contains !== 'function') {
        return false;
    }

    return parent.contains(child);
};

// Attach an event listener to an element
export const eventOn = (el, eventName, handler) => {
    if (el && el.addEventListener) {
        el.addEventListener(eventName, handler);
    }
};

// Remove an event listener from an element
export const eventOff = (el, eventName, handler) => {
    if (el && el.removeEventListener) {
        el.removeEventListener(eventName, handler);
    }
};

// Filter visible elements
export const filterVisible = elements => (elements || []).filter(isVisible);

// Return the Bounding Client Rect of an element
// Returns `null` if not an element
export const getBCR = el => (isElement(el) ? el.getBoundingClientRect() : null);

// Determine if an element is an HTML element
const isElement = el => Boolean(el && el.nodeType === Node.ELEMENT_NODE);

// Determine if an HTML element is visible - Faster than CSS check
const isVisible = el => {
    if (! isElement(el) || ! contains(document.body, el)) {
        return false;
    }

    if (el.style.display === 'none') {
        return false;
    }

    const bcr = getBCR(el);

    return Boolean(bcr && bcr.height > 0 && bcr.width > 0);
};

// Select all elements matching a selector. Returns `[]` if none found
export const selectAll = (selector, root) =>
    arrayFrom((isElement(root) ? root : document).querySelectorAll(selector));

// Set an attribute on an element
export const setAttr = (el, attr, value) => {
    if (attr && isElement(el)) {
        el.setAttribute(attr, value);
    }
};

export const parentElementByClassName = (element, className) => {
    let parentElement = element.parentElement;

    while (parentElement !== null && !parentElement.classList.contains(className)) {
        parentElement = parentElement.parentElement;
    }

    return parentElement;
};