facilitate caching repository responses in content scripts

1 files changed, 84 insertions, 0 deletions

diff --git a/content/repo_query_cacher.js b/content/repo_query_cacher.js
new file mode 100644
index 0000000..bdba189
--- /dev/null
+++ b/content/repo_query_cacher.js
@@ -0,0 +1,84 @@
+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Caching responses from remote repositories and serving them to
+ *           popup pages.
+ *
+ * Copyright (C) 2022 Wojtek Kosior
+ *
+ * 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.
+ *
+ * As additional permission under GNU GPL version 3 section 7, you
+ * may distribute forms of that code without the copy of the GNU
+ * GPL normally required by section 4, provided you include this
+ * license notice and, in case of non-source distribution, a URL
+ * through which recipients can access the Corresponding Source.
+ * If you modify file(s) with this exception, you may extend this
+ * exception to your version of the file(s), but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * As a special exception to the GPL, any HTML file which merely
+ * makes function calls to this code, and for that purpose
+ * includes it by reference shall be deemed a separate work for
+ * copyright law purposes. If you modify this code, you may extend
+ * this exception to your version of the code, but you are not
+ * obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ * I, Wojtek Kosior, thereby promise not to sue for violation of this file's
+ * license. Although I request that you do not make use of this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+/*
+ * Map URLs to objects containing parsed responses, error info or promises
+ * resolving to those.
+ */
+const cache = new Map();
+
+async function perform_download(url) {
+    if (cache.has(url))
+	return cache.get(url);
+
+    let resolve_cb;
+    cache.set(url, new Promise(cb => resolve_cb = cb));
+
+    try {
+	const opts = {url, to_get: ["ok", "status"], to_call: ["json"]};
+	var result = await browser.runtime.sendMessage(["CORS_bypass", opts]);
+	if (result === undefined)
+	    result = {error: "Couldn't communicate with background script."};
+    } catch(e) {
+	var result = {error: e + ""};
+    }
+
+    cache.set(url, result);
+    resolve_cb(result);
+
+    return result;
+}
+
+function on_repo_query_request([type, url], sender, respond_cb) {
+    if (type !== "repo_query")
+	return;
+
+    perform_download(url).then(respond_cb);
+
+    return true;
+}
+
+function start() {
+    browser.runtime.onMessage.addListener(on_repo_query_request);
+}