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haketilo / content / repo_query_cacher.js @ 13a707c6

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/**
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 * This file is part of Haketilo.
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 *
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 * Function: Caching responses from remote repositories and serving them to
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 *           popup pages.
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 *
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 * Copyright (C) 2022 Wojtek Kosior
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 *
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 * This program is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * As additional permission under GNU GPL version 3 section 7, you
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 * may distribute forms of that code without the copy of the GNU
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 * GPL normally required by section 4, provided you include this
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 * license notice and, in case of non-source distribution, a URL
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 * through which recipients can access the Corresponding Source.
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 * If you modify file(s) with this exception, you may extend this
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 * exception to your version of the file(s), but you are not
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 * obligated to do so. If you do not wish to do so, delete this
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 * exception statement from your version.
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 *
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 * As a special exception to the GPL, any HTML file which merely
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 * makes function calls to this code, and for that purpose
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 * includes it by reference shall be deemed a separate work for
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 * copyright law purposes. If you modify this code, you may extend
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 * this exception to your version of the code, but you are not
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 * obligated to do so. If you do not wish to do so, delete this
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 * exception statement from your version.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
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 *
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 * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
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 * license. Although I request that you do not make use of this code in a
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 * proprietary program, I am not going to enforce this in court.
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 */
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#FROM common/browser.js IMPORT browser
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#FROM common/misc.js    IMPORT error_data_jsonifiable
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/*
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 * Map URLs to objects containing parsed responses, error info or promises
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 * resolving to those. The use of promises helps us prevent multiple requests
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 * for the same resource from starting concurrently.
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 */
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const cache = new Map();
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async function perform_download(url) {
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    if (cache.has(url))
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	return cache.get(url);
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    let resolve_cb;
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    cache.set(url, new Promise(cb => resolve_cb = cb));
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    try {
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	var result = await browser.runtime.sendMessage(["CORS_bypass", {url}]);
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	if (result === undefined)
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	    throw new Error("Couldn't communicate with background script.");
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    } catch(e) {
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	return {error: error_data_jsonifiable(e)};
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    }
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    cache.set(url, result);
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    resolve_cb(result);
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    return result;
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}
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function on_repo_query_request([type, url], sender, respond_cb) {
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    if (type !== "repo_query")
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	return;
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    perform_download(url).then(respond_cb);
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    return true;
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}
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function start() {
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    browser.runtime.onMessage.addListener(on_repo_query_request);
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}
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#EXPORT start
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