/**
 * This file is part of Haketilo.
 *
 * Function: Allow content scripts to query IndexedDB through messages to
 *           background script.
 *
 * Copyright (C) 2022 Wojtek Kosior <koszko@koszko.org>
 *
 * 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/indexeddb.js AS haketilodb

#FROM common/browser.js IMPORT browser

async function get_resource_files(getting, id) {
    if (getting.defs_by_res_id.has(id))
	return;

    getting.defs_by_res_id.set(id, null);

    const definition = await haketilodb.idb_get(getting.tx, "resource", id);
    if (!definition)
	throw {haketilo_error_type: "missing", id};

    getting.defs_by_res_id.set(id, definition);

    const file_proms = (definition.scripts || [])
	  .map(s => haketilodb.idb_get(getting.tx, "file", s.sha256));

    const deps_proms = (definition.dependencies || [])
	  .map(res_ref => get_resource_files(getting, res_ref.identifier));

    const files = (await Promise.all(file_proms)).map(f => f.contents);
    getting.files_by_res_id.set(id, files);

    await Promise.all(deps_proms);
}

function get_files_list(defs_by_res_id, files_by_res_id, root_id) {
    const processed = new Set(), to_process = [["start", root_id]],
	  trace = new Set(), files = [];

    while (to_process.length > 0) {
	const [what, id] = to_process.pop();
	if (what === "end") {
	    trace.delete(id);
	    files.push(...files_by_res_id.get(id));
	    continue;
	}

	if (trace.has(id))
	    throw {haketilo_error_type: "circular", id};

	if (processed.has(id))
	    continue;

	trace.add(id);
	to_process.push(["end", id]);
	processed.add(id);

	const ds = (defs_by_res_id.get(id).dependencies || []).reverse();
	ds.forEach(res_ref => to_process.push(["start", res_ref.identifier]));
    }

    return files;
}

async function send_resource_files(root_resource_id, send_cb) {
    const db = await haketilodb.get();
    const getting = {
	defs_by_res_id:  new Map(),
	files_by_res_id: new Map(),
	tx:              db.transaction(["file", "resource"])
    };

    let prom_cbs, prom = new Promise((...cbs) => prom_cbs = cbs);

    getting.tx.onerror = e => prom_cbs[1]({haketilo_error_type: "db", e});

    get_resource_files(getting, root_resource_id, new Set()).then(...prom_cbs);

    try {
	await prom;
	const files = get_files_list(
	    getting.defs_by_res_id,
	    getting.files_by_res_id,
	    root_resource_id
	);
	var to_send = {files};
    } catch(e) {
	if (typeof e === "object" && "haketilo_error_type" in e) {
	    if (e.haketilo_error_type === "db") {
		console.error("Haketilo:", e.e);
		delete e.e;
	    }
	    var to_send = {error: e};
	} else {
	    console.error("Haketilo:", e);
	    var to_send = {error: {haketilo_error_type: "other"}};
	}
    }

    send_cb(to_send);
}

function on_indexeddb_files_request([type, resource_id], sender, respond_cb) {
    if (type !== "indexeddb_files")
	return;

    send_resource_files(resource_id, respond_cb);

    return true;
}

function start() {
    browser.runtime.onMessage.addListener(on_indexeddb_files_request);
}
#EXPORT start