Haketilo

/**

 * This file is part of Haketilo.

 *

 * Function: Instantiate the Pattern Tree data structure, filled with mappings

 *           from IndexedDB.

 *

 * Copyright (C) 2021,2022 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.

 */

#IMPORT common/patterns_query_tree.js  AS pqt

#IMPORT common/indexeddb.js            AS haketilodb

#IF MOZILLA || MV3

#FROM common/browser.js IMPORT browser

#ENDIF

let secret;

const tree = pqt.make();

#EXPORT tree

const currently_registered = new Map();

#IF MOZILLA || MV3

let registered_script = null;

let script_update_occuring = false;

let script_update_needed;

async function update_content_script()

{

    if (script_update_occuring)

	return;

    script_update_occuring = true;

    while (script_update_needed) {

	script_update_needed = false;

	const code = `\

this.haketilo_secret       = ${secret};

this.haketilo_pattern_tree = ${JSON.stringify(tree)};

if (this.haketilo_content_script_main)

    haketilo_content_script_main();`;

	const new_script = await browser.contentScripts.register({

	    "js": [{code}],

	    "matches": ["<all_urls>"],

	    "allFrames": true,

	    "runAt": "document_start"

	});

	if (registered_script)

	    registered_script.unregister();

	registered_script = new_script;

    }

    script_update_occuring = false;

}

#ENDIF

function register(kind, object)

{

    if (kind === "mappings") {

	for (const [pattern, resource] of Object.entries(object.payloads))

	    pqt.register(tree, pattern, object.identifier, resource);

    } else /* if (kind === "blocking") */ {

	/*

	 * All simple block/allow rules use "~allow" in place of mapping id.

	 * This way it won't collide with any real mapping id and will always

	 * be sorted as higher value than mapping ids.

	 */

	pqt.register(tree, object.pattern, "~allow", object.allow + 0);

    }

#IF MOZILLA || MV3

    const id = kind === "mappings" ? object.identifier : object.pattern;

    currently_registered.set(id, object);

#ENDIF

}

function changed(kind, change)

{

    const old_version = currently_registered.get(change.key);

    if (old_version !== undefined) {

	if (kind === "mappings") {

	    for (const pattern in old_version.payloads)

		pqt.deregister(tree, pattern, change.key);

	} else /* if (kind === "blocking") */ {

	    pqt.deregister(tree, change.key, "~allow");

	}

#IF MOZILLA || MV3

	currently_registered.delete(change.key);

#ENDIF

    }

    if (change.new_val !== undefined)

	register(kind, change.new_val);

#IF MOZILLA || MV3

    script_update_needed = true;

    setTimeout(update_content_script, 0);

#ENDIF

}

async function start(secret_)

{

    secret = secret_;

    const [mapping_tracking, initial_mappings] =

	  await haketilodb.track.mapping(ch => changed("mappings", ch));

    const [blocking_tracking, initial_blocking] =

	  await haketilodb.track.blocking(ch => changed("blocking", ch));

    initial_mappings.forEach(m => register("mappings", m));

    initial_blocking.forEach(b => register("blocking", b));

#IF MOZILLA || MV3

    script_update_needed = true;

    await update_content_script();

#ENDIF

}

#EXPORT start