/**
 * Copyright 2013-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule EventPluginHub
 */

'use strict';

var _prodInvariant = require('./reactProdInvariant');

var EventPluginRegistry = require('./EventPluginRegistry');
var EventPluginUtils = require('./EventPluginUtils');
var ReactErrorUtils = require('./ReactErrorUtils');

var accumulateInto = require('./accumulateInto');
var forEachAccumulated = require('./forEachAccumulated');
var invariant = require('fbjs/lib/invariant');

/**
 * Internal store for event listeners
 */
var listenerBank = {};

/**
 * Internal queue of events that have accumulated their dispatches and are
 * waiting to have their dispatches executed.
 */
var eventQueue = null;

/**
 * Dispatches an event and releases it back into the pool, unless persistent.
 *
 * @param {?object} event Synthetic event to be dispatched.
 * @param {boolean} simulated If the event is simulated (changes exn behavior)
 * @private
 */
var executeDispatchesAndRelease = function (event, simulated) {
  if (event) {
    EventPluginUtils.executeDispatchesInOrder(event, simulated);

    if (!event.isPersistent()) {
      event.constructor.release(event);
    }
  }
};
var executeDispatchesAndReleaseSimulated = function (e) {
  return executeDispatchesAndRelease(e, true);
};
var executeDispatchesAndReleaseTopLevel = function (e) {
  return executeDispatchesAndRelease(e, false);
};

var getDictionaryKey = function (inst) {
  // Prevents V8 performance issue:
  // https://github.com/facebook/react/pull/7232
  return '.' + inst._rootNodeID;
};

/**
 * This is a unified interface for event plugins to be installed and configured.
 *
 * Event plugins can implement the following properties:
 *
 *   `extractEvents` {function(string, DOMEventTarget, string, object): *}
 *     Required. When a top-level event is fired, this method is expected to
 *     extract synthetic events that will in turn be queued and dispatched.
 *
 *   `eventTypes` {object}
 *     Optional, plugins that fire events must publish a mapping of registration
 *     names that are used to register listeners. Values of this mapping must
 *     be objects that contain `registrationName` or `phasedRegistrationNames`.
 *
 *   `executeDispatch` {function(object, function, string)}
 *     Optional, allows plugins to override how an event gets dispatched. By
 *     default, the listener is simply invoked.
 *
 * Each plugin that is injected into `EventsPluginHub` is immediately operable.
 *
 * @public
 */
var EventPluginHub = {

  /**
   * Methods for injecting dependencies.
   */
  injection: {

    /**
     * @param {array} InjectedEventPluginOrder
     * @public
     */
    injectEventPluginOrder: EventPluginRegistry.injectEventPluginOrder,

    /**
     * @param {object} injectedNamesToPlugins Map from names to plugin modules.
     */
    injectEventPluginsByName: EventPluginRegistry.injectEventPluginsByName

  },

  /**
   * Stores `listener` at `listenerBank[registrationName][key]`. Is idempotent.
   *
   * @param {object} inst The instance, which is the source of events.
   * @param {string} registrationName Name of listener (e.g. `onClick`).
   * @param {function} listener The callback to store.
   */
  putListener: function (inst, registrationName, listener) {
    !(typeof listener === 'function') ? process.env.NODE_ENV !== 'production' ? invariant(false, 'Expected %s listener to be a function, instead got type %s', registrationName, typeof listener) : _prodInvariant('94', registrationName, typeof listener) : void 0;

    var key = getDictionaryKey(inst);
    var bankForRegistrationName = listenerBank[registrationName] || (listenerBank[registrationName] = {});
    bankForRegistrationName[key] = listener;

    var PluginModule = EventPluginRegistry.registrationNameModules[registrationName];
    if (PluginModule && PluginModule.didPutListener) {
      PluginModule.didPutListener(inst, registrationName, listener);
    }
  },

  /**
   * @param {object} inst The instance, which is the source of events.
   * @param {string} registrationName Name of listener (e.g. `onClick`).
   * @return {?function} The stored callback.
   */
  getListener: function (inst, registrationName) {
    var bankForRegistrationName = listenerBank[registrationName];
    var key = getDictionaryKey(inst);
    return bankForRegistrationName && bankForRegistrationName[key];
  },

  /**
   * Deletes a listener from the registration bank.
   *
   * @param {object} inst The instance, which is the source of events.
   * @param {string} registrationName Name of listener (e.g. `onClick`).
   */
  deleteListener: function (inst, registrationName) {
    var PluginModule = EventPluginRegistry.registrationNameModules[registrationName];
    if (PluginModule && PluginModule.willDeleteListener) {
      PluginModule.willDeleteListener(inst, registrationName);
    }

    var bankForRegistrationName = listenerBank[registrationName];
    // TODO: This should never be null -- when is it?
    if (bankForRegistrationName) {
      var key = getDictionaryKey(inst);
      delete bankForRegistrationName[key];
    }
  },

  /**
   * Deletes all listeners for the DOM element with the supplied ID.
   *
   * @param {object} inst The instance, which is the source of events.
   */
  deleteAllListeners: function (inst) {
    var key = getDictionaryKey(inst);
    for (var registrationName in listenerBank) {
      if (!listenerBank.hasOwnProperty(registrationName)) {
        continue;
      }

      if (!listenerBank[registrationName][key]) {
        continue;
      }

      var PluginModule = EventPluginRegistry.registrationNameModules[registrationName];
      if (PluginModule && PluginModule.willDeleteListener) {
        PluginModule.willDeleteListener(inst, registrationName);
      }

      delete listenerBank[registrationName][key];
    }
  },

  /**
   * Allows registered plugins an opportunity to extract events from top-level
   * native browser events.
   *
   * @return {*} An accumulation of synthetic events.
   * @internal
   */
  extractEvents: function (topLevelType, targetInst, nativeEvent, nativeEventTarget) {
    var events;
    var plugins = EventPluginRegistry.plugins;
    for (var i = 0; i < plugins.length; i++) {
      // Not every plugin in the ordering may be loaded at runtime.
      var possiblePlugin = plugins[i];
      if (possiblePlugin) {
        var extractedEvents = possiblePlugin.extractEvents(topLevelType, targetInst, nativeEvent, nativeEventTarget);
        if (extractedEvents) {
          events = accumulateInto(events, extractedEvents);
        }
      }
    }
    return events;
  },

  /**
   * Enqueues a synthetic event that should be dispatched when
   * `processEventQueue` is invoked.
   *
   * @param {*} events An accumulation of synthetic events.
   * @internal
   */
  enqueueEvents: function (events) {
    if (events) {
      eventQueue = accumulateInto(eventQueue, events);
    }
  },

  /**
   * Dispatches all synthetic events on the event queue.
   *
   * @internal
   */
  processEventQueue: function (simulated) {
    // Set `eventQueue` to null before processing it so that we can tell if more
    // events get enqueued while processing.
    var processingEventQueue = eventQueue;
    eventQueue = null;
    if (simulated) {
      forEachAccumulated(processingEventQueue, executeDispatchesAndReleaseSimulated);
    } else {
      forEachAccumulated(processingEventQueue, executeDispatchesAndReleaseTopLevel);
    }
    !!eventQueue ? process.env.NODE_ENV !== 'production' ? invariant(false, 'processEventQueue(): Additional events were enqueued while processing an event queue. Support for this has not yet been implemented.') : _prodInvariant('95') : void 0;
    // This would be a good time to rethrow if any of the event handlers threw.
    ReactErrorUtils.rethrowCaughtError();
  },

  /**
   * These are needed for tests only. Do not use!
   */
  __purge: function () {
    listenerBank = {};
  },

  __getListenerBank: function () {
    return listenerBank;
  }

};

module.exports = EventPluginHub;