import SafeString from "./safe-string";

var isArray = Array.isArray;

var escape = {
  "&": "&",
  "<": "&lt;",
  ">": "&gt;",
  '"': "&quot;",
  "'": "&#x27;",
  "`": "&#x60;"
};

var badChars = /[&<>"'`]/g;
var possible = /[&<>"'`]/;

function escapeChar(chr) {
  return escape[chr] || "&amp;";
}

export function extend(obj, value) {
  for(var key in value) {
    if(value.hasOwnProperty(key)) {
      obj[key] = value[key];
    }
  }
}

export function escapeExpression(string) {
  // don't escape SafeStrings, since they're already safe
  if (string instanceof SafeString) {
    return string.toString();
  } else if (!string && string !== 0) {
    return "";
  }

  // Force a string conversion as this will be done by the append regardless and
  // the regex test will do this transparently behind the scenes, causing issues if
  // an object's to string has escaped characters in it.
  string = "" + string;

  if(!possible.test(string)) { return string; }
  return string.replace(badChars, escapeChar);
}

export function isEmpty(value) {
  if (!value && value !== 0) {
    return true;
  } else if (isArray(value) && value.length === 0) {
    return true;
  } else {
    return false;
  }
}