var twoDecimals = /^\d+(.\d{1,2})?$/
var positiveInteger = /^\d+$/
var realName = /^[\u4e00-\u9fa5]{2,12}$/

function isTwoDecimals(target) {
  return twoDecimals.test(target)
}

function isPositiveInteger(target) {
  return positiveInteger.test(target)
}

function isRealName(target) {
  return realName.test(target)
}

function isIdentityCard(code) {
  var city = { 11: "北京", 12: "天津", 13: "河北", 14: "山西", 15: "内蒙古", 21: "辽宁", 22: "吉林", 23: "黑龙江 ", 31: "上海", 32: "江苏", 33: "浙江", 34: "安徽", 35: "福建", 36: "江西", 37: "山东", 41: "河南", 42: "湖北 ", 43: "湖南", 44: "广东", 45: "广西", 46: "海南", 50: "重庆", 51: "四川", 52: "贵州", 53: "云南", 54: "西藏 ", 61: "陕西", 62: "甘肃", 63: "青海", 64: "宁夏", 65: "新疆", 71: "台湾", 81: "香港", 82: "澳门", 91: "国外 " };
  var pass = true;

  if (!code || !/^\d{6}(18|19|20)?\d{2}(0[1-9]|1[012])(0[1-9]|[12]\d|3[01])\d{3}(\d|X)$/i.test(code)) {
    return false
  }else if (!city[code.substr(0, 2)]) {
    return false;
  }else {
    //18位身份证需要验证最后一位校验位
    if (code.length == 18) {
      code = code.split('');
      //∑(ai×Wi)(mod 11)
      //加权因子
      var factor = [7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2];
      //校验位
      var parity = [1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2];
      var sum = 0;
      var ai = 0;
      var wi = 0;
      for (var i = 0; i < 17; i++) {
        ai = code[i];
        wi = factor[i];
        sum += ai * wi;
      }
      var last = parity[sum % 11];
      if (parity[sum % 11] != code[17]) {
        return false;
      }
    }
  }
  return true;
}

module.exports = {
  isTwoDecimals: isTwoDecimals,
  isPositiveInteger: isPositiveInteger,
  isRealName: isRealName,
  isIdentityCard: isIdentityCard,
}