/**
 * @license
 * Copyright (C) 2017 The Android Open Source Project
 *
 * 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.
 */
(function(window) {
  'use strict';

  function GrPluginEndpoints() {
    this._endpoints = {};
    this._callbacks = {};
    this._dynamicPlugins = {};
  }

  GrPluginEndpoints.prototype.onNewEndpoint = function(endpoint, callback) {
    if (!this._callbacks[endpoint]) {
      this._callbacks[endpoint] = [];
    }
    this._callbacks[endpoint].push(callback);
  };

  GrPluginEndpoints.prototype.onDetachedEndpoint = function(endpoint,
      callback) {
    if (this._callbacks[endpoint]) {
      this._callbacks[endpoint] = this._callbacks[endpoint]
          .filter(cb => cb !== callback);
    }
  };

  GrPluginEndpoints.prototype._getOrCreateModuleInfo = function(plugin,
      endpoint, type, moduleName, domHook) {
    const existingModule = this._endpoints[endpoint].find(info =>
      info.plugin === plugin &&
        info.moduleName === moduleName &&
        info.domHook === domHook
    );
    if (existingModule) {
      return existingModule;
    } else {
      const newModule = {
        moduleName,
        plugin,
        pluginUrl: plugin._url,
        type,
        domHook,
      };
      this._endpoints[endpoint].push(newModule);
      return newModule;
    }
  };

  /**
   * Register a plugin to an endpoint.
   *
   * Dynamic plugins are registered to a specific prefix, such as
   * 'change-list-header'. These plugins are then fetched by prefix to determine
   * which endpoints to dynamically add to the page.
   */
  GrPluginEndpoints.prototype.registerModule = function(plugin, endpoint, type,
      moduleName, domHook, dynamicEndpoint) {
    if (dynamicEndpoint) {
      if (!this._dynamicPlugins[dynamicEndpoint]) {
        this._dynamicPlugins[dynamicEndpoint] = new Set();
      }
      this._dynamicPlugins[dynamicEndpoint].add(endpoint);
    }
    if (!this._endpoints[endpoint]) {
      this._endpoints[endpoint] = [];
    }
    const moduleInfo = this._getOrCreateModuleInfo(plugin, endpoint, type,
        moduleName, domHook);
    if (Gerrit._arePluginsLoaded() && this._callbacks[endpoint]) {
      this._callbacks[endpoint].forEach(callback => callback(moduleInfo));
    }
  };

  GrPluginEndpoints.prototype.getDynamicEndpoints = function(dynamicEndpoint) {
    const plugins = this._dynamicPlugins[dynamicEndpoint];
    if (!plugins) return [];
    return Array.from(plugins);
  };

  /**
   * Get detailed information about modules registered with an extension
   * endpoint.
   *
   * @param {string} name Endpoint name.
   * @param {?{
   *   type: (string|undefined),
   *   moduleName: (string|undefined)
   * }} opt_options
   * @return {!Array<{
   *   moduleName: string,
   *   plugin: Plugin,
   *   pluginUrl: String,
   *   type: EndpointType,
   *   domHook: !Object
   * }>}
   */
  GrPluginEndpoints.prototype.getDetails = function(name, opt_options) {
    const type = opt_options && opt_options.type;
    const moduleName = opt_options && opt_options.moduleName;
    if (!this._endpoints[name]) {
      return [];
    }
    return this._endpoints[name]
        .filter(item => (!type || item.type === type) &&
                    (!moduleName || moduleName == item.moduleName));
  };

  /**
   * Get detailed module names for instantiating at the endpoint.
   *
   * @param {string} name Endpoint name.
   * @param {?{
   *   type: (string|undefined),
   *   moduleName: (string|undefined)
   * }} opt_options
   * @return {!Array<string>}
   */
  GrPluginEndpoints.prototype.getModules = function(name, opt_options) {
    const modulesData = this.getDetails(name, opt_options);
    if (!modulesData.length) {
      return [];
    }
    return modulesData.map(m => m.moduleName);
  };

  /**
   * Get .html plugin URLs with element and module definitions.
   *
   * @param {string} name Endpoint name.
   * @param {?{
   *   type: (string|undefined),
   *   moduleName: (string|undefined)
   * }} opt_options
   * @return {!Array<!URL>}
   */
  GrPluginEndpoints.prototype.getPlugins = function(name, opt_options) {
    const modulesData =
          this.getDetails(name, opt_options).filter(
              data => data.pluginUrl.pathname.includes('.html'));
    if (!modulesData.length) {
      return [];
    }
    return Array.from(new Set(modulesData.map(m => m.pluginUrl)));
  };

  window.GrPluginEndpoints = GrPluginEndpoints;
})(window);