var args = [
	{
		domain: /^(.*\.)?facebook\.com$/,
		args: ['__tn__', '__xts__[0]']
	}, {
		domain: /^(.*\.)?instagram\.com$/,
		args: ['igshid']
	}, {
		domain: /^(.*\.)?youtube\.com$/,
		args: ['feature']
	}, {
		domain: /^(.*\.)?repubblica\.it$/,
		args: ['ref']
	}, {
		domain: /./,
		args: ['fbclid', 'gclid',
			'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
			'refresh_ce']
	}
];

function sanitizeUrl(node, url, list) {
	var changed;

	for (var i = 0; i < list.length; i++) {
		if (url.searchParams.has(list[i])) {
			changed = true;
			url.searchParams.delete(list[i]);
		}
	}

	if (changed)
		node.value = url.toString();
}

function sanitizeNode(node) {
	if (node.tagName != 'A')
		return;

	var href = node.attributes['href'];
	if (!href)
		return;

	href = href.value;
	url = new URL(href, location.origin);

	if (url.protocol != 'http:' && url.protocol != 'https:')
		return;

	for (var i = 0; i < args.length; i++)
		if (url.hostname.match(args[i].domain))
			sanitizeUrl(node.attributes['href'], url, args[i].args);
}

function walk(node) {
	// thanks to: http://is.gd/mwZp7E
	switch (node.nodeType) {
		case  1: // Node.ELEMENT_NODE
			sanitizeNode(node);
		case  9: // Node.DOCUMENT_NODE
		case 11: // Node.DOCUMENT_FRAGMENT_NODE
			var child = node.firstChild;
			while (child) {
				var next = child.nextSibling;
				walk(child);
				child = next;
			}
			break;
	}
}

// register a MutationObserver to handle DOM edits by client-side JS.
new MutationObserver(function (mlist) {
	for (var i = 0; i < mlist.length; i++)
		walk(mlist[i].target);
}).observe(document, {
	childList: true,
	subtree: true,
	attributes: true,
	attributeFilter: ['href'],
})

walk(document.body);