/**
 * Myext injecting policy to page using webRequest
 *
 * Copyright (C) 2021 Wojtek Kosior
 * Redistribution terms are gathered in the `copyright' file.
 */

/*
 * IMPORTS_START
 * IMPORT TYPE_PREFIX
 * IMPORT get_storage
 * IMPORT browser
 * IMPORT is_chrome
 * IMPORT gen_unique
 * IMPORT url_item
 * IMPORT get_query_best
 * IMPORT csp_rule
 * IMPORTS_END
 */

var storage;
var query_best;

let csp_header_names = {
    "content-security-policy" : true,
    "x-webkit-csp" : true,
    "x-content-security-policy" : true
};

function is_noncsp_header(header)
{
    return !csp_header_names[header.name.toLowerCase()];
}

function inject(details)
{
    let url = url_item(details.url);

    let [pattern, settings] = query_best(url);

    if (settings !== undefined && settings.allow)
	return {cancel : false};

    let nonce = gen_unique(url);
    let headers = details.responseHeaders.filter(is_noncsp_header);

    headers.push({
	name : "content-security-policy",
	value : csp_rule(nonce)
    });

    return {responseHeaders: headers};
}

async function start_policy_injector()
{
    storage = await get_storage();
    query_best = await get_query_best();

    let extra_opts = ["blocking", "responseHeaders"];
    if (is_chrome)
	extra_opts.push("extraHeaders");

    browser.webRequest.onHeadersReceived.addListener(
	inject,
	{
	    urls: ["<all_urls>"],
	    types: ["main_frame", "sub_frame"]
	},
	extra_opts
    );
}

/*
 * EXPORTS_START
 * EXPORT start_policy_injector
 * EXPORTS_END
 */