#!/usr/bin/env node
import { readdirSync, readFileSync, readlinkSync } from 'fs';
import { execFileSync } from 'child_process';

const window_id = process.argv[2];
if (!window_id) {
	console.error('Usage: debug-window.js <window-id>');
	process.exit(1);
}

function read_file(path) {
	try { return readFileSync(path, 'utf8'); } catch { return null; }
}

function get_ppid(pid) {
	const status = read_file(`/proc/${pid}/status`);
	const match = status?.match(/^PPid:\s+(\d+)/m);
	return match ? match[1] : null;
}

function get_comm(pid) {
	return read_file(`/proc/${pid}/comm`)?.trim() ?? null;
}

function get_cmdline(pid) {
	return read_file(`/proc/${pid}/cmdline`)?.replace(/\0/g, ' ').trim() ?? null;
}

// Get PID of the window
const out = execFileSync('xprop', ['-id', window_id, '_NET_WM_PID'], { encoding: 'utf8' });
const match = out.match(/= (\d+)/);
if (!match) {
	console.error('Could not get PID for window', window_id);
	process.exit(1);
}
const root_pid = match[1];
console.log(`Window ${window_id} → PID ${root_pid} (${get_comm(root_pid)})`);

// Find all descendants
const children = new Map(); // pid → [child pids]
for (const entry of readdirSync('/proc')) {
	if (!/^\d+$/.test(entry)) continue;
	const ppid = get_ppid(entry);
	if (!ppid) continue;
	if (!children.has(ppid)) children.set(ppid, []);
	children.get(ppid).push(entry);
}

function print_tree(pid, depth = 0) {
	const indent = '  '.repeat(depth);
	const comm = get_comm(pid) ?? '?';
	const cmdline = get_cmdline(pid) ?? '';
	console.log(`${indent}${pid} [${comm}] ${cmdline.slice(0, 120)}`);
	for (const child of children.get(pid) ?? []) {
		print_tree(child, depth + 1);
	}
}

print_tree(root_pid);