SingleFile/lib/fetch/bg/fetch.js

/*
 * Copyright 2018 Gildas Lormeau
 * contact : gildas.lormeau <at> gmail.com
 * 
 * This file is part of SingleFile.
 *
 *   SingleFile is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   SingleFile 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with SingleFile.  If not, see <http://www.gnu.org/licenses/>.
 */

/* global fetch */

(() => {

	const browser = this.browser || this.chrome;

	const fetchResponses = new Map();

	let requestId = 1;

	browser.runtime.onMessage.addListener((request, sender, send) => {
		const sendResponse = response => {
			if (request.method.startsWith("fetch.")) {
				fetchResponses.delete(request.requestId);
			}
			send(response);
		};
		try {
			onRequest(request, sendResponse);
		} catch (error) {
			sendResponse({ error });
		}
		return true;
	});

	async function onRequest(request, sendResponse) {
		if (request.method) {
			if (request.method == "fetch") {
				const responseId = requestId;
				requestId = requestId + 1;
				let response;
				try {
					response = await fetch(request.url, request.options);
				} catch (error) {
					sendResponse({ error });
				}
				if (response) {
					if (response.status >= 400) {
						sendResponse({ error: new Error(response.statusText || response.status) });
					} else {
						fetchResponses.set(responseId, response);
						const headers = {};
						for (let headerName of response.headers.keys()) {
							headers[headerName] = response.headers.get(headerName);
						}
						sendResponse({ responseId, headers });
					}
				}
			}
			if (request.method == "fetch.array") {
				const content = fetchResponses.get(request.requestId);
				try {
					const buffer = await content.arrayBuffer();
					sendResponse({ array: Array.from(new Uint8Array(buffer)) });
				} catch (error) {
					sendResponse({ error });
				}
			}
			if (request.method == "fetch.text") {
				const content = fetchResponses.get(request.requestId);
				try {
					const text = await content.text();
					sendResponse({ text });
				} catch (error) {
					sendResponse({ error });
				}
			}
		}
	}

})();