
/** Used as the `TypeError` message for "Functions" methods. */
var FUNC_ERROR_TEXT = 'Expected a function';

/** Used as references for various `Number` constants. */
var NAN = 0 / 0;

/** `Object#toString` result references. */
var symbolTag = '[object Symbol]';

/** Used to match leading and trailing whitespace. */
var reTrim = /^\s+|\s+$/g;

/** Used to detect bad signed hexadecimal string values. */
var reIsBadHex = /^[-+]0x[0-9a-f]+$/i;

/** Used to detect binary string values. */
var reIsBinary = /^0b[01]+$/i;

/** Used to detect octal string values. */
var reIsOctal = /^0o[0-7]+$/i;

/** Built-in method references without a dependency on `root`. */
var freeParseInt = parseInt;

/** Detect free variable `global` from Node.js. */
var freeGlobal = typeof global == 'object' && global && global.Object === Object && global;

/** Detect free variable `self`. */
var freeSelf = typeof self == 'object' && self && self.Object === Object && self;

/** Used as a reference to the global object. */
var root = freeGlobal || freeSelf || Function('return this')();

/** Used for built-in method references. */
var objectProto = Object.prototype;

/**
 * Used to resolve the
 * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
 * of values.
 */
var objectToString = objectProto.toString;

/* Built-in method references for those with the same name as other `lodash` methods. */
var nativeMax = Math.max,
    nativeMin = Math.min;

var now = function() {
  return root.Date.now();
};


function debounce(func, wait, options) {
  var lastArgs,
      lastThis,
      maxWait,
      result,
      timerId,
      lastCallTime,
      lastInvokeTime = 0,
      leading = false,
      maxing = false,
      trailing = true;

  if (typeof func != 'function') {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  wait = toNumber(wait) || 0;
  if (isObject(options)) {
    leading = !!options.leading;
    maxing = 'maxWait' in options;
    maxWait = maxing ? nativeMax(toNumber(options.maxWait) || 0, wait) : maxWait;
    trailing = 'trailing' in options ? !!options.trailing : trailing;
  }

  function invokeFunc(time) {
    var args = lastArgs,
        thisArg = lastThis;

    lastArgs = lastThis = undefined;
    lastInvokeTime = time;
    result = func.apply(thisArg, args);
    return result;
  }

  function leadingEdge(time) {
    // Reset any `maxWait` timer.
    lastInvokeTime = time;
    // Start the timer for the trailing edge.
    timerId = setTimeout(timerExpired, wait);
    // Invoke the leading edge.
    return leading ? invokeFunc(time) : result;
  }

  function remainingWait(time) {
    var timeSinceLastCall = time - lastCallTime,
        timeSinceLastInvoke = time - lastInvokeTime,
        result = wait - timeSinceLastCall;

    return maxing ? nativeMin(result, maxWait - timeSinceLastInvoke) : result;
  }

  function shouldInvoke(time) {
    var timeSinceLastCall = time - lastCallTime,
        timeSinceLastInvoke = time - lastInvokeTime;

    // Either this is the first call, activity has stopped and we're at the
    // trailing edge, the system time has gone backwards and we're treating
    // it as the trailing edge, or we've hit the `maxWait` limit.
    return (lastCallTime === undefined || (timeSinceLastCall >= wait) ||
      (timeSinceLastCall < 0) || (maxing && timeSinceLastInvoke >= maxWait));
  }

  function timerExpired() {
    var time = now();
    if (shouldInvoke(time)) {
      return trailingEdge(time);
    }
    // Restart the timer.
    timerId = setTimeout(timerExpired, remainingWait(time));
  }

  function trailingEdge(time) {
    timerId = undefined;

    // Only invoke if we have `lastArgs` which means `func` has been
    // debounced at least once.
    if (trailing && lastArgs) {
      return invokeFunc(time);
    }
    lastArgs = lastThis = undefined;
    return result;
  }

  function cancel() {
    if (timerId !== undefined) {
      clearTimeout(timerId);
    }
    lastInvokeTime = 0;
    lastArgs = lastCallTime = lastThis = timerId = undefined;
  }

  function flush() {
    return timerId === undefined ? result : trailingEdge(now());
  }

  function debounced() {
    var time = now(),
        isInvoking = shouldInvoke(time);

    lastArgs = arguments;
    lastThis = this;
    lastCallTime = time;

    if (isInvoking) {
      if (timerId === undefined) {
        return leadingEdge(lastCallTime);
      }
      if (maxing) {
        // Handle invocations in a tight loop.
        timerId = setTimeout(timerExpired, wait);
        return invokeFunc(lastCallTime);
      }
    }
    if (timerId === undefined) {
      timerId = setTimeout(timerExpired, wait);
    }
    return result;
  }
  debounced.cancel = cancel;
  debounced.flush = flush;
  return debounced;
}

function isObject(value) {
  var type = typeof value;
  return !!value && (type == 'object' || type == 'function');
}

function isObjectLike(value) {
  return !!value && typeof value == 'object';
}

function isSymbol(value) {
  return typeof value == 'symbol' ||
    (isObjectLike(value) && objectToString.call(value) == symbolTag);
}

function toNumber(value) {
  if (typeof value == 'number') {
    return value;
  }
  if (isSymbol(value)) {
    return NAN;
  }
  if (isObject(value)) {
    var other = typeof value.valueOf == 'function' ? value.valueOf() : value;
    value = isObject(other) ? (other + '') : other;
  }
  if (typeof value != 'string') {
    return value === 0 ? value : +value;
  }
  value = value.replace(reTrim, '');
  var isBinary = reIsBinary.test(value);
  return (isBinary || reIsOctal.test(value))
    ? freeParseInt(value.slice(2), isBinary ? 2 : 8)
    : (reIsBadHex.test(value) ? NAN : +value);
}

export default  debounce;
