/** \file
 * \brief Main script launched when a page is being loaded by a browser
 *
 *  \author Copyright (C) 2020  Libor Polcak
 *  \author Copyright (C) 2021  Matus Svancar
 *  \author Copyright (C) 2021  Giorgio Maone
 *  \author Copyright (C) 2021  Marek Salon
 *  \author Copyright (C) 2023  Martin Zmitko
 *
 *  \license SPDX-License-Identifier: GPL-3.0-or-later
 */
//
//  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.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <https://www.gnu.org/licenses/>.
//

var wrappersPort;
var pageConfiguration = null;
function configureInjection({currentLevel, fpdWrappers, domainHash}) {
	if (pageConfiguration) return; // one shot
	pageConfiguration = {currentLevel};
	if(browser.extension.inIncognitoContext){
		// Redefine the domainHash for incognito context:
		// Compute the SHA256 hash of the original hash so that the incognito hash is:
		// * significantly different to the original domainHash,
		// * computationally difficult to revert,
		// * the same for all incognito windows (for the same domain).
		var hash = sha256.create();
		hash.update(JSON.stringify(domainHash));
		domainHash = hash.hex();
	}
	// Append argument reporting setting to JSS wrapper definitions
	fp_append_reporting_to_jss_wrappers(fpdWrappers);
	// Generate wrapping code
	var code = wrap_code(currentLevel.wrappers);
	// Generate FPD wrapping code
	if (fpdWrappers) {
		if (!code) {
			code = fp_generate_wrapping_code(fpdWrappers);
		}
		else {
			code = fp_update_wrapping_code(code, currentLevel.wrappers, fpdWrappers);
		}
	}
	// Insert farbling WASM module into wrapped code if enabled, only when farbling is actually used 
	if (currentLevel.wasm && (currentLevel.audiobuffer === 1 || currentLevel.htmlcanvaselement === 1)) {
		code = insert_wasm_code(code);
	}

	var aleaCode = `(() => {
	var domainHash =  ${JSON.stringify(domainHash)};
	${crc16}
	${alea}
	var prng = alea(domainHash); // Do not use this in wrappers, create your own prng to generate repeatable sequences
	${code}
	})()`;
	try {
		wrappersPort = patchWindow(aleaCode);	
		wrappersPort.onMessage = msg => {
			if (msg.wrapperName) {
				let {wrapperName, wrapperType, wrapperArgs} = msg;			
				// pass access logs to FPD background script
				browser.runtime.sendMessage({
					purpose: "fp-detection",
					resource: wrapperName,
					type: wrapperType,
					args: wrapperArgs,
				});
			}
		}
		return true;
	} catch (e) {
		console.error(e, `Trying to run\n${aleaCode}`)
	}
	return false;
}

/**
 * See https://pagure.io/JShelter/paper2022/c/a7e7e88edecfa19c3a52542b553bf1dc9b4388a9?branch=cnil,
 * https://pagure.io/JShelter/webextension/issue/70 and
 * https://pagure.io/JShelter/webextension/issue/46#comment-793783
 * for more information on the early injection mechanism.
 */
if ("configuration" in window) {
	configureInjection(configuration);
} else {
	/// Get current level configuration from the background script
	configureInjection(browser.runtime.sendSyncMessage({
			message: "get wrapping for URL",
			url: window.location.href
		}
	));
}

/**
 * Event listener that listens for background script messages.
 *
 * \param callback Function that clears certain storage facilities.
 */
browser.runtime.onMessage.addListener(function (message) {
	if (message.cleanStorage) { 
		localStorage.clear();
		sessionStorage.clear();
		window.name = "";

		if (!message.ignoreWorkaround) {
			// clear indexedDB (only Chrome)
			if (window.indexedDB && indexedDB.databases) {	
				indexedDB.databases().then(dbs => {
					dbs.forEach(db => indexedDB.deleteDatabase(db.name))
				}).catch(err => console.error(err));
			}
		
			// clear cacheStorage
			if (window.caches) {
				caches.keys().then((names) => {
					for (let name of names) {
						caches.delete(name);
					}
				}).catch(err => console.error(err));
			}

			// clear cookies (only JS)
			// Source: https://stackoverflow.com/a/66698063/17661959
			document.cookie.replace(
				/(?<=^|;).+?(?=\=|;|$)/g, 
				name => location.hostname
				  .split(/\.(?=[^\.]+\.)/)
				  .reduceRight((acc, val, i, arr) => i ? arr[i]='.'+val+acc : (arr[i]='', arr), '')
				  .map(domain => document.cookie=`${name}=;${location.protocol == 'https:' ? 'Secure;' : ''}max-age=0;path=/;domain=${domain}`)
			);
		}

		// clear storages of all injected windows (using BrowsingData)
		browser.runtime.sendMessage({
			purpose: "fpd-clear-storage",
			url: window.location.href
		});
	}
});