'use strict';

var clones = require('clones');

var hasWindow = typeof window !== 'undefined';
exports.hasWindow = hasWindow;
var hasGlobal = typeof global !== 'undefined';
exports.hasGlobal = hasGlobal;
var FN_NOOP = 'function () {}';
var NON_IDENTIFIER = /^\d|-|^(break|case|catch|continue|debugger|default|delete|do|else|finally|for|function|if|in|instanceof|new|return|switch|this|throw|try|typeof|var|void|while|with|class|const|enum|export|extends|import|super|implements|interface|let|package|private|protected|public|static|yield|null|true|false)$/;

var isIdentifier = function isIdentifier(key) {
  return !NON_IDENTIFIER.test(key);
};

exports.isIdentifier = isIdentifier;
/**
* create a fresh context where nearly nothing is allowed
* @private
*/

exports.createContext = function () {
  // protection might not be complete!
  var context = {
    // disallowed
    global: undefined,
    process: undefined,
    module: undefined,
    require: undefined,
    document: undefined,
    window: undefined,
    Window: undefined,
    // no evil...
    eval: undefined,
    Function: undefined
  };

  var fillContext = function fillContext(root) {
    Object.keys(root).forEach(function (key) {
      if (isIdentifier(key)) {
        context[key] = undefined;
      }
    });
  }; // locally define all potential global vars


  if (hasGlobal) {
    fillContext(global);
    cloneFunctions(context);
    context.Buffer = _protect('Buffer');
    context.console = clones(console, console); // console needs special treatment

    context.console.constructor.constructor = FN_NOOP;
  }

  if (hasWindow) {
    fillContext(window, true);
    cloneFunctions(context);
    protectBuiltInObjects(context);
    context.console = clones(console, console); // console needs special treatment

    try {
      context.Object.constructor.constructor = FN_NOOP;
    } catch (e) {}
  }

  return context;
};
/**
* Apply allowed context properties
* @private
*/


exports.allow = function (context, newContext) {
  Object.keys(context || {}).forEach(function (key) {
    if (isIdentifier(key)) {
      newContext[key] = context[key]; // this is harmful - objects can be overwritten
    }
  });
};
/**
* clone global functions
* @private
*/


function cloneFunctions(context) {
  ;
  ['clearImmediate', 'clearInterval', 'clearTimeout'].forEach(function (str) {
    try {
      var fn = new Function("return ".concat(str))(); // eslint-disable-line no-new-func

      context[str] = fn ? function () {
        return fn.apply(null, [].slice.call(arguments));
      } : undefined;
    } catch (e) {}
  });
  ['setImmediate', 'setInterval', 'setTimeout'].forEach(function (str) {
    try {
      var fn = new Function("return ".concat(str))(); // eslint-disable-line no-new-func

      context[str] = fn ? function (f) {
        if (typeof f === 'function') {
          return fn.apply(null, [].slice.call(arguments));
        } else {
          throw new Error(str + ' requires function as argument');
        }
      } : undefined;
    } catch (e) {}
  });
}
/**
* wraps up build-in objects using a cloned copy
* protect object against overwriting
* @private
*/


function protectBuiltInObjects(context) {
  ;
  ['Object', 'Boolean', 'Symbol', 'Error', 'EvalError', 'InternalError', 'RangeError', 'ReferenceError', 'SyntaxError', 'TypeError', 'URIError', 'Number', 'Math', 'Date', 'String', 'RegExp', 'Array', 'Int8Array', 'Uint8Array', 'Uint8ClampedArray', 'Int16Array', 'Uint16Array', 'Int32Array', 'Uint32Array', 'Float32Array', 'Float64Array', 'Map', 'Set', 'WeakMap', 'WeakSet', 'ArrayBuffer', 'SharedArrayBuffer', 'Atomics', 'DataView', 'JSON', 'Promise', 'Generator', 'GeneratorFunction', 'Reflect', 'Proxy', 'Intl', 'Buffer'].forEach(function (str) {
    try {
      context[str] = _protect(str);
      new context[str](); // eslint-disable-line no-new
    } catch (e) {}
  });
}
/**
* @private
*/


function _protect(str) {
  try {
    var type = new Function("return ".concat(str))(); // eslint-disable-line no-new-func

    return type ? clones.classes(type) : undefined;
  } catch (e) {}
}