Haketilo

/**

 * This file is part of Haketilo.

 *

 * Function: Storage manager, lighter than the previous one.

 *

 * Copyright (C) 2021 Wojtek Kosior

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

 */

/*

 * IMPORTS_START

 * IMPORT TYPE_PREFIX

 * IMPORT raw_storage

 * IMPORT is_mozilla

 * IMPORT observables

 * IMPORTS_END

 */

const reg_spec = new Set(["\\", "[", "]", "(", ")", "{", "}", ".", "*", "+"]);

const escape_reg_special = c => reg_spec.has(c) ? "\\" + c : c;

function make_regex(name)

{

    return new RegExp(`^${name.split("").map(escape_reg_special).join("")}\$`);

}

const listeners_by_callback = new Map();

function listen(callback, prefix, name)

{

    let by_prefix = listeners_by_callback.get(callback);

    if (!by_prefix) {

	by_prefix = new Map();

	listeners_by_callback.set(callback, by_prefix);

    }

    let by_name = by_prefix.get(prefix);

    if (!by_name) {

	by_name = new Map();

	by_prefix.set(prefix, by_name);

    }

    let name_reg = by_name.get(name);

    if (!name_reg) {

	name_reg = name.test ? name : make_regex(name);

	by_name.set(name, name_reg);

    }

}

function no_listen(callback, prefix, name)

{

    const by_prefix = listeners_by_callback.get(callback);

    if (!by_prefix)

	return;

    const by_name = by_prefix.get(prefix);

    if (!by_name)

	return;

    const name_reg = by_name.get(name);

    if (!name_reg)

	return;

    by_name.delete(name);

    if (by_name.size === 0)

	by_prefix.delete(prefix);

    if (by_prefix.size === 0)

	listeners_by_callback.delete(callback);

}

function storage_change_callback(changes, area)

{

    if (is_mozilla && area !== "local")

    {console.log("area", area);return;}

    for (const item of Object.keys(changes)) {

	for (const [callback, by_prefix] of listeners_by_callback.entries()) {

	    const by_name = by_prefix.get(item[0]);

	    if (!by_name)

		continue;

	    for (const reg of by_name.values()) {

		if (!reg.test(item.substring(1)))

		    continue;

		try {

		    callback(item, changes[item]);

		} catch(e) {

		    console.error(e);

		}

	    }

	}

    }

}

raw_storage.listen(storage_change_callback);

const created_observables = new Map();

async function observe(prefix, name)

{

    const observable = observables.make();

    const callback = (it, ch) => observables.set(observable, ch.newValue);

    listen(callback, prefix, name);

    created_observables.set(observable, [callback, prefix, name]);

    observables.silent_set(observable, await raw_storage.get(prefix + name));

    return observable;

}

const observe_var = name => observe(TYPE_PREFIX.VAR, name);

function no_observe(observable)

{

    no_listen(...created_observables.get(observable) || []);

    created_observables.delete(observable);

}

const light_storage = {};

Object.assign(light_storage, raw_storage);

Object.assign(light_storage,

	      {listen, no_listen, observe, observe_var, no_observe});

/*

 * EXPORTS_START

 * EXPORT light_storage

 * EXPORTS_END

 */