Haketilo

/**

 * Myext storage through connection (client side)

 *

 * Copyright (C) 2021 Wojtek Kosior

 * Redistribution terms are gathered in the `copyright' file.

 */

"use strict";

(() => {

    const CONNECTION_TYPE = window.CONNECTION_TYPE;

    const TYPE_PREFIX = window.TYPE_PREFIX;

    const list_prefixes = window.list_prefixes;

    const make_once = window.make_once;

    const browser = window.browser;

    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);

    }

    function list(name, prefix)

    {

	return {prefix, name, listeners : new Set()};

    }

    var scripts = list("scripts", TYPE_PREFIX.SCRIPT);

    var bags = list("bags", TYPE_PREFIX.BAG);

    var pages = list("pages", TYPE_PREFIX.PAGE);

    const list_by_prefix = {

	[TYPE_PREFIX.SCRIPT] : scripts,

	[TYPE_PREFIX.BAG] : bags,

	[TYPE_PREFIX.PAGE] : pages

    };

    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]);

    }

    window.get_storage = make_once(init);

})();