function isValidUrl(url) {
  return isOnlineUrl(url) || isDataUrl(url);
}

function isOnlineUrl(url) {
  return /((ht|f)tp(s?)|cloud):\/\/([^ \\/]*\.)+[^ \\/]*(:[0-9]+)?\/?/.test(url)
}

function isDataUrl(url) {
  return /data:image\/(\w+);base64,(.*)/.test(url);
}

/**
 * 深度对比两个对象是否一致
 * from: https://github.com/epoberezkin/fast-deep-equal
 * @param  {Object} a 对象a
 * @param  {Object} b 对象b
 * @return {Boolean}   是否相同
 */
/* eslint-disable */
function equal(a, b) {
  if (a === b) return true;

  if (a && b && typeof a == 'object' && typeof b == 'object') {
    var arrA = Array.isArray(a)
      , arrB = Array.isArray(b)
      , i
      , length
      , key;

    if (arrA && arrB) {
      length = a.length;
      if (length != b.length) return false;
      for (i = length; i-- !== 0;)
        if (!equal(a[i], b[i])) return false;
      return true;
    }

    if (arrA != arrB) return false;

    var dateA = a instanceof Date
      , dateB = b instanceof Date;
    if (dateA != dateB) return false;
    if (dateA && dateB) return a.getTime() == b.getTime();

    var regexpA = a instanceof RegExp
      , regexpB = b instanceof RegExp;
    if (regexpA != regexpB) return false;
    if (regexpA && regexpB) return a.toString() == b.toString();

    var keys = Object.keys(a);
    length = keys.length;

    if (length !== Object.keys(b).length)
      return false;

    for (i = length; i-- !== 0;)
      if (!Object.prototype.hasOwnProperty.call(b, keys[i])) return false;

    for (i = length; i-- !== 0;) {
      key = keys[i];
      if (!equal(a[key], b[key])) return false;
    }

    return true;
  }

  return a!==a && b!==b;
}

module.exports = {
  isValidUrl,
  isOnlineUrl,
  isDataUrl,
  equal
};