/**
 * @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.
 */

import {pluginLoader} from './gr-plugin-loader.js';

/** @constructor */
export 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, opts) {
  const {endpoint, slot, type, moduleName, domHook} = opts;
  const existingModule = this._endpoints[endpoint].find(info =>
    info.plugin === plugin &&
      info.moduleName === moduleName &&
      info.domHook === domHook &&
      info.slot === slot
  );
  if (existingModule) {
    return existingModule;
  } else {
    const newModule = {
      moduleName,
      plugin,
      pluginUrl: plugin._url,
      type,
      domHook,
      slot,
    };
    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.
 *
 * @param {Object} plugin
 * @param {Object} opts
 */
GrPluginEndpoints.prototype.registerModule = function(plugin, opts) {
  const {endpoint, dynamicEndpoint} = opts;
  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, opts);
  if (pluginLoader.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)));
};

// TODO(dmfilippov): Convert to service and add to appContext
export let pluginEndpoints = new GrPluginEndpoints();
export function _testOnly_resetEndpoints() {
  pluginEndpoints = new GrPluginEndpoints();
}