/**
 * Copyright 2013 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule ReactPerf
 * @typechecks static-only
 */

"use strict";

var ReactPerf = {
  /**
   * Boolean to enable/disable measurement. Set to false by default to prevent
   * accidental logging and perf loss.
   */
  enableMeasure: false,

  /**
   * Holds onto the measure function in use. By default, don't measure
   * anything, but we'll override this if we inject a measure function.
   */
  storedMeasure: _noMeasure,

  /**
   * Use this to wrap methods you want to measure.
   *
   * @param {string} objName
   * @param {string} fnName
   * @param {function} func
   * @return {function}
   */
  measure: function(objName, fnName, func) {
    if (__DEV__) {
      var measuredFunc = null;
      return function() {
        if (ReactPerf.enableMeasure) {
          if (!measuredFunc) {
            measuredFunc = ReactPerf.storedMeasure(objName, fnName, func);
          }
          return measuredFunc.apply(this, arguments);
        }
        return func.apply(this, arguments);
      };
    }
    return func;
  },

  injection: {
    /**
     * @param {function} measure
     */
    injectMeasure: function(measure) {
      ReactPerf.storedMeasure = measure;
    }
  }
};

if (__DEV__) {
  var ExecutionEnvironment = require('ExecutionEnvironment');
  var url = (ExecutionEnvironment.canUseDOM && window.location.href) || '';
  ReactPerf.enableMeasure = ReactPerf.enableMeasure ||
    (/[?&]react_perf\b/).test(url);
}

/**
 * Simply passes through the measured function, without measuring it.
 *
 * @param {string} objName
 * @param {string} fnName
 * @param {function} func
 * @return {function}
 */
function _noMeasure(objName, fnName, func) {
  return func;
}

module.exports = ReactPerf;
