blob: 2d1d3ac8a3e438500fb363da7a2b9897ffc9a94a [file] [log] [blame]
/**
* @license
* Copyright (C) 2016 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 '../gr-js-api-interface/gr-js-api-interface.js';
import {GestureEventListeners} from '@polymer/polymer/lib/mixins/gesture-event-listeners.js';
import {LegacyElementMixin} from '@polymer/polymer/lib/legacy/legacy-element-mixin.js';
import {PolymerElement} from '@polymer/polymer/polymer-element.js';
import {htmlTemplate} from './gr-lib-loader_html.js';
// preloaded in PolyGerritIndexHtml.soy
const HLJS_PATH = 'bower_components/highlightjs/highlight.min.js';
/** @extends PolymerElement */
class GrLibLoader extends GestureEventListeners(
LegacyElementMixin(
PolymerElement)) {
static get template() { return htmlTemplate; }
static get is() { return 'gr-lib-loader'; }
static get properties() {
return {
_hljsState: {
type: Object,
// NOTE: intended singleton.
value: {
configured: false,
loading: false,
callbacks: [],
},
},
};
}
/**
* Get the HLJS library. Returns a promise that resolves with a reference to
* the library after it's been loaded. The promise resolves immediately if
* it's already been loaded.
*
* @return {!Promise<Object>}
*/
getHLJS() {
return new Promise((resolve, reject) => {
// If the lib is totally loaded, resolve immediately.
if (this._getHighlightLib()) {
resolve(this._getHighlightLib());
return;
}
// If the library is not currently being loaded, then start loading it.
if (!this._hljsState.loading) {
this._hljsState.loading = true;
this._loadScript(this._getHLJSUrl())
.then(this._onHLJSLibLoaded.bind(this))
.catch(reject);
}
this._hljsState.callbacks.push(resolve);
});
}
/**
* Execute callbacks awaiting the HLJS lib load.
*/
_onHLJSLibLoaded() {
const lib = this._getHighlightLib();
this._hljsState.loading = false;
this.$.jsAPI.handleEvent(this.$.jsAPI.EventType.HIGHLIGHTJS_LOADED, {
hljs: lib,
});
for (const cb of this._hljsState.callbacks) {
cb(lib);
}
this._hljsState.callbacks = [];
}
/**
* Get the HLJS library, assuming it has been loaded. Configure the library
* if it hasn't already been configured.
*
* @return {!Object}
*/
_getHighlightLib() {
const lib = window.hljs;
if (lib && !this._hljsState.configured) {
this._hljsState.configured = true;
lib.configure({classPrefix: 'gr-diff gr-syntax gr-syntax-'});
}
return lib;
}
/**
* Get the resource path used to load the application. If the application
* was loaded through a CDN, then this will be the path to CDN resources.
*
* @return {string}
*/
_getLibRoot() {
if (window.STATIC_RESOURCE_PATH) {
return window.STATIC_RESOURCE_PATH + '/';
}
return '/';
}
/**
* Load and execute a JS file from the lib root.
*
* @param {string} src The path to the JS file without the lib root.
* @return {Promise} a promise that resolves when the script's onload
* executes.
*/
_loadScript(src) {
return new Promise((resolve, reject) => {
const script = document.createElement('script');
if (!src) {
reject(new Error('Unable to load blank script url.'));
return;
}
script.setAttribute('src', src);
script.onload = resolve;
script.onerror = reject;
document.head.appendChild(script);
});
}
_getHLJSUrl() {
const root = this._getLibRoot();
if (!root) { return null; }
return root + HLJS_PATH;
}
}
customElements.define(GrLibLoader.is, GrLibLoader);