// ==========================================================================
// Type checking utils
// ==========================================================================

const getConstructor = input => (input !== null && typeof input !== 'undefined' ? input.constructor : null);
const instanceOf = (input, constructor) => Boolean(input && constructor && input instanceof constructor);
const isNullOrUndefined = input => input === null || typeof input === 'undefined';
const isObject = input => getConstructor(input) === Object;
const isNumber = input => getConstructor(input) === Number && !Number.isNaN(input);
const isString = input => getConstructor(input) === String;
const isBoolean = input => getConstructor(input) === Boolean;
const isFunction = input => getConstructor(input) === Function;
const isArray = input => Array.isArray(input);
const isWeakMap = input => instanceOf(input, WeakMap);
const isNodeList = input => instanceOf(input, NodeList);
const isElement = input => instanceOf(input, Element);
const isTextNode = input => getConstructor(input) === Text;
const isEvent = input => instanceOf(input, Event);
const isKeyboardEvent = input => instanceOf(input, KeyboardEvent);
const isCue = input => instanceOf(input, window.TextTrackCue) || instanceOf(input, window.VTTCue);
const isTrack = input => instanceOf(input, TextTrack) || (!isNullOrUndefined(input) && isString(input.kind));

const isEmpty = input =>
    isNullOrUndefined(input) ||
    ((isString(input) || isArray(input) || isNodeList(input)) && !input.length) ||
    (isObject(input) && !Object.keys(input).length);

const isUrl = input => {
    // Accept a URL object
    if (instanceOf(input, window.URL)) {
        return true;
    }

    // Add the protocol if required
    let string = input;
    if (!input.startsWith('http://') || !input.startsWith('https://')) {
        string = `http://${input}`;
    }

    try {
        return !isEmpty(new URL(string).hostname);
    } catch (e) {
        return false;
    }
};

export default {
    nullOrUndefined: isNullOrUndefined,
    object: isObject,
    number: isNumber,
    string: isString,
    boolean: isBoolean,
    function: isFunction,
    array: isArray,
    weakMap: isWeakMap,
    nodeList: isNodeList,
    element: isElement,
    textNode: isTextNode,
    event: isEvent,
    keyboardEvent: isKeyboardEvent,
    cue: isCue,
    track: isTrack,
    url: isUrl,
    empty: isEmpty,
};