/**
 * @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 {BaseUrlBehavior} from '../base-url-behavior/base-url-behavior.js';

const PROBE_PATH = '/Documentation/index.html';
const DOCS_BASE_PATH = '/Documentation';

let cachedPromise;

/** @polymerBehavior DocsUrlBehavior */
export const DocsUrlBehavior = [{

  /**
   * Get the docs base URL from either the server config or by probing.
   *
   * @param {Object} config The server config.
   * @param {!Object} restApi A REST API instance
   * @return {!Promise<string>} A promise that resolves with the docs base
   *     URL.
   */
  getDocsBaseUrl(config, restApi) {
    if (!cachedPromise) {
      cachedPromise = new Promise(resolve => {
        if (config && config.gerrit && config.gerrit.doc_url) {
          resolve(config.gerrit.doc_url);
        } else {
          restApi.probePath(this.getBaseUrl() + PROBE_PATH).then(ok => {
            resolve(ok ? (this.getBaseUrl() + DOCS_BASE_PATH) : null);
          });
        }
      });
    }
    return cachedPromise;
  },

  /** For testing only. */
  _clearDocsBaseUrlCache() {
    cachedPromise = undefined;
  },
},
BaseUrlBehavior,
];

// TODO(dmfilippov) Remove the following lines with assignments
// Plugins can use the behavior because it was accessible with
// the global Gerrit... variable. To avoid breaking changes in plugins
// temporary assign global variables.
window.Gerrit = window.Gerrit || {};
window.Gerrit.DocsUrlBehavior = DocsUrlBehavior;