Haketilo

/**

 * This file is part of Haketilo.

 *

 * Function: Storage through messages (client side).

 *

 * Copyright (C) 2021 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 this code in a

 * proprietary program, I am not going to enforce this in court.

 */

/*

 * IMPORTS_START

 * IMPORT CONNECTION_TYPE

 * IMPORT list_prefixes

 * IMPORT make_once

 * IMPORT browser

 * IMPORTS_END

 */

var call_id = 0;

var port;

var calls_waiting = new Map();

function set_call_callback(resolve, reject, func, args)

{

    port.postMessage([call_id, func, args]);

    calls_waiting.set(call_id++, [resolve, reject]);

}

async function remote_call(func, args)

{

    return new Promise((resolve, reject) =>

		       set_call_callback(resolve, reject, func, args));

}

function handle_message(message)

{

    let callbacks = calls_waiting.get(message.call_id);

    if (callbacks === undefined) {

	handle_change(message);

	return;

    }

    let [resolve, reject] = callbacks;

    calls_waiting.delete(message.call_id);

    if (message.error !== undefined)

	setTimeout(reject, 0, message.error);

    else

	setTimeout(resolve, 0, message.result);

}

const list_by_prefix = {};

for (const prefix of list_prefixes)

    list_by_prefix[prefix] = {prefix, listeners : new Set()};

var resolve_init;

function handle_first_message(message)

{

    for (let prefix of Object.keys(message))

	list_by_prefix[prefix].map = new Map(message[prefix]);

    port.onMessage.removeListener(handle_first_message);

    port.onMessage.addListener(handle_message);

    resolve_init();

}

function handle_change(change)

{

    let list = list_by_prefix[change.prefix];

    if (change.new_val === undefined)

	list.map.delete(change.item);

    else

	list.map.set(change.item, change.new_val);

    for (let listener_callback of list.listeners)

	listener_callback(change);

}

var exports = {};

function start_connection(resolve)

{

    resolve_init = resolve;

    port = browser.runtime.connect({name : CONNECTION_TYPE.REMOTE_STORAGE});

    port.onMessage.addListener(handle_first_message);

}

async function init() {

    await new Promise((resolve, reject) => start_connection(resolve));

    return exports;

}

for (let call_name of ["set", "remove", "replace", "clear"])

    exports [call_name] = (...args) => remote_call(call_name, args);

// TODO: Much of the code below is copy-pasted from /background/storage.mjs.

//       This should later be refactored into a separate module

//       to avoid duplication.

/*

 * Facilitate listening to changes

 */

exports.add_change_listener = function (cb, prefixes=list_prefixes)

{

    if (typeof(prefixes) === "string")

	prefixes = [prefixes];

    for (let prefix of prefixes)

	list_by_prefix[prefix].listeners.add(cb);

}

exports.remove_change_listener = function (cb, prefixes=list_prefixes)

{

    if (typeof(prefixes) === "string")

	prefixes = [prefixes];

    for (let prefix of prefixes)

	list_by_prefix[prefix].listeners.delete(cb);

}

/* Prepare some hepler functions to get elements of a list */

function list_items_it(list, with_values=false)

{

    return with_values ? list.map.entries() : list.map.keys();

}

function list_entries_it(list)

{

    return list_items_it(list, true);

}

function list_items(list, with_values=false)

{

    let array = [];

    for (let item of list_items_it(list, with_values))

	array.push(item);

    return array;

}

function list_entries(list)

{

    return list_items(list, true);

}

exports.get = function (prefix, item)

{

    return list_by_prefix[prefix].map.get(item);

}

exports.get_all_names = function (prefix)

{

    return list_items(list_by_prefix[prefix]);

}

exports.get_all_names_it = function (prefix)

{

    return list_items_it(list_by_prefix[prefix]);

}

exports.get_all = function (prefix)

{

    return list_entries(list_by_prefix[prefix]);

}

exports.get_all_it = function (prefix)

{

    return list_entries_it(list_by_prefix[prefix]);

}

const get_remote_storage = make_once(init);

/*

 * EXPORTS_START

 * EXPORT get_remote_storage

 * EXPORTS_END

 */