/**
 * 随机选取数组中的一个值
 */
function randomSelectOne(arr) {
  return arr[Math.floor(Math.random()*(arr.length -1))];
}

/**
 * 随机选取数组中的N个值
 */
function randomSelectN(arr) {
    let MAX = Math.floor(Math.random()*(arr.length - 1));
    return arr.slice(0, MAX);
}

/**
 * 解析url中参数
 */
export function getUrlParams(url) {
  const d = decodeURIComponent;
  let queryString = url ? url.split('?')[1] : window.location.search.slice(1);
  const obj = {};
  if (queryString) {
    queryString = queryString.split('#')[0]; // eslint-disable-line
    const arr = queryString.split('&');
    for (let i = 0; i < arr.length; i += 1) {
      const a = arr[i].split('=');
      let paramNum;
      const paramName = a[0].replace(/\[\d*\]/, (v) => {
        paramNum = v.slice(1, -1);
        return '';
      });
      const paramValue = typeof (a[1]) === 'undefined' ? true : a[1];
      if (obj[paramName]) {
        if (typeof obj[paramName] === 'string') {
          obj[paramName] = d([obj[paramName]]);
        }
        if (typeof paramNum === 'undefined') {
          obj[paramName].push(d(paramValue));
        } else {
          obj[paramName][paramNum] = d(paramValue);
        }
      } else {
        obj[paramName] = d(paramValue);
      }
    }
  }
  return obj;
}

module.exports = {
  randomSelectOne,
  randomSelectN,
  getUrlParams,
}