facilitate initialization of IndexedDB for use by Haketilo

1 files changed, 148 insertions, 0 deletions

diff --git a/common/entities.js b/common/entities.js
new file mode 100644
index 0000000..46836b5
--- /dev/null
+++ b/common/entities.js
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+/**
+ * This file is part of Haketilo.
+ *
+ * Function: Operations on resources and mappings.
+ *
+ * Copyright (C) 2021 Wojtek Kosior <koszko@koszko.org>
+ *
+ * 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 this code in a
+ * proprietary program, I am not going to enforce this in court.
+ */
+
+/*
+ * Convert ver_str into an array representation, e.g. for ver_str="4.6.13.0"
+ * return [4, 6, 13, 0].
+ */
+const parse_version = ver_str => ver_str.split(".").map(parseInt);
+
+/*
+ * ver is an array of integers. rev is an optional integer. Produce string
+ * representation of version (optionally with revision number), like:
+ *     1.2.3-5
+ * No version normalization is performed.
+ */
+const version_string = (ver, rev=0) => ver.join(".") + (rev ? `-${rev}` : "");
+
+/* vers should be an array of comparable values. Return the greatest one. */
+const max = vals => Array.reduce(vals, (v1, v2) => v1 > v2 ? v1 : v2);
+
+/*
+ * versioned_item should be a dict with keys being version strings and values
+ * being definitions of the respective versions of a single resource/mapping.
+ * Example:
+ *     {
+ *         "1": {
+ *             version: [1]//,
+ *             // more stuff
+ *         },
+ *         "1.1": {
+ *             version: [1, 1]//,
+ *             // more stuff
+ *         }
+ *      }
+ *
+ * Returns the definition with the highest version.
+ */
+function get_newest_version(versioned_item)
+{
+    const best_ver = max(Object.keys(versioned_item).map(parse_version));
+    return versioned_item[version_string(best_ver)];
+}
+
+/*
+ * item is a definition of a resource or mapping. Yield all file references
+ * (objects with `file` and `sha256` properties) this definition has.
+ */
+function* get_used_files(item)
+{
+    for (const file of item.source_copyright)
+	yield file;
+
+    if (item.type === "resource") {
+	for (const file of item.scripts || [])
+	    yield file;
+    }
+}
+
+const entities = {
+    get_newest: get_newest_version,
+    get_files:  get_used_files
+};
+
+/*
+ * EXPORTS_START
+ * EXPORT entities
+ * EXPORTS_END
+ */
+
+/*
+ * Note: the functions below were overeagerly written and are not used now but
+ * might prove useful to once we add more functionalities and are hence kept...
+ */
+
+/*
+ * Clone recursively all objects. Leave other items (arrays, strings) untouched.
+ */
+function deep_object_copy(object)
+{
+    const orig = {object};
+    const result = {};
+    const to_copy = [[orig, {}]];
+
+    while (to_copy.length > 0) {
+	const [object, copy] = to_copy.pop();
+
+	for (const [key, value] of Object.entries(object)) {
+	    copy[key] = value;
+
+	    if (typeof value === "object" && !Array.isArray(value)) {
+		const value_copy = {};
+		to_copy.push([value, value_copy]);
+		copy[key] = value_copy;
+	    }
+	}
+    }
+
+    return result.orig;
+}
+
+/* helper function for normalize_version() */
+const version_reductor = (acc, n) => [...(n || acc.length ? [n] : []), ...acc];
+/*
+ * ver is an array of integers. Strip right-most zeroes from ver.
+ *
+ * Returns a *new* array. Doesn't modify its argument.
+ */
+const normalize_version = ver => Array.reduceRight(ver, version_reductor, []);