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-rw-r--r--ext/fg/js/frontend-api-sender.js125
1 files changed, 125 insertions, 0 deletions
diff --git a/ext/fg/js/frontend-api-sender.js b/ext/fg/js/frontend-api-sender.js
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+++ b/ext/fg/js/frontend-api-sender.js
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+/*
+ * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class FrontendApiSender {
+ constructor() {
+ this.ackTimeout = 3000; // 3 seconds
+ this.responseTimeout = 10000; // 10 seconds
+ this.callbacks = {};
+ this.disconnected = false;
+ this.nextId = 0;
+
+ this.port = chrome.runtime.connect(null, {name: 'backend-api-forwarder'});
+ this.port.onDisconnect.addListener(this.onDisconnect.bind(this));
+ this.port.onMessage.addListener(this.onMessage.bind(this));
+ }
+
+ invoke(action, params, target) {
+ if (this.disconnected) {
+ return Promise.reject('Disconnected');
+ }
+
+ const id = `${this.nextId}`;
+ ++this.nextId;
+
+ return new Promise((resolve, reject) => {
+ const info = {id, resolve, reject, ack: false, timer: null};
+ this.callbacks[id] = info;
+ info.timer = setTimeout(() => this.onError(id, 'Timeout (ack)'), this.ackTimeout);
+
+ this.port.postMessage({id, action, params, target});
+ });
+ }
+
+ onMessage({type, id, data}) {
+ switch (type) {
+ case 'ack':
+ this.onAck(id);
+ break;
+ case 'result':
+ this.onResult(id, data);
+ break;
+ }
+ }
+
+ onDisconnect() {
+ this.disconnected = true;
+
+ const ids = Object.keys(this.callbacks);
+ for (const id of ids) {
+ this.onError(id, 'Disconnected');
+ }
+ }
+
+ onAck(id) {
+ if (!this.callbacks.hasOwnProperty(id)) {
+ console.warn(`ID ${id} not found`);
+ return;
+ }
+
+ const info = this.callbacks[id];
+ if (info.ack) {
+ console.warn(`Request ${id} already ack'd`);
+ return;
+ }
+
+ info.ack = true;
+ clearTimeout(info.timer);
+ info.timer = setTimeout(() => this.onError(id, 'Timeout (response)'), this.responseTimeout);
+ }
+
+ onResult(id, data) {
+ if (!this.callbacks.hasOwnProperty(id)) {
+ console.warn(`ID ${id} not found`);
+ return;
+ }
+
+ const info = this.callbacks[id];
+ if (!info.ack) {
+ console.warn(`Request ${id} not ack'd`);
+ return;
+ }
+
+ delete this.callbacks[id];
+ clearTimeout(info.timer);
+ info.timer = null;
+
+ if (typeof data.error === 'string') {
+ info.reject(data.error);
+ } else {
+ info.resolve(data.result);
+ }
+ }
+
+ onError(id, reason) {
+ if (!this.callbacks.hasOwnProperty(id)) { return; }
+ const info = this.callbacks[id];
+ delete this.callbacks[id];
+ info.timer = null;
+ info.reject(reason);
+ }
+
+ static generateId(length) {
+ let id = '';
+ for (let i = 0; i < length; ++i) {
+ id += Math.floor(Math.random() * 256).toString(16).padStart(2, '0');
+ }
+ return id;
+ }
+}