/*
 * SPDX-FileCopyrightText: 2025 Eilertsens Kodeknekkeri
 * SPDX-FileCopyrightText: 2025 The FreeBSD Foundation
 * SPDX-FileContributor: Harald Eilertsen <haraldei@anduin.net>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "helpers.hpp"
#include <cassert>
#include <iostream>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <unistd.h>

void sysctl_cpu_time(pthread_t thread, struct timeval * utime, struct timeval * stime) {
	int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_PID|KERN_PROC_INC_THREAD, getpid() };

	auto miblen = sizeof mib / sizeof mib[0];
	size_t bufsize = 0;

	auto rc = sysctl(mib, miblen, nullptr, &bufsize, nullptr, 0);
	// for some reason it seems sysctl sometimes return 0 (Ok) instead of ENOMEM when
	// passed a nullptr as oldp. This is not according to documentation.
	assert(rc == ENOMEM || rc == 0);

	auto procinfo_buf = malloc(bufsize);
	rc = sysctl(mib, 4U, procinfo_buf, &bufsize, nullptr, 0);
	assert(rc == 0);

	auto count = bufsize / sizeof(struct kinfo_proc);

#ifndef NDEBUG
	std::cout << "[*] Received procinfo @ " << procinfo_buf
		<< ", with " << count << " entries" << std::endl;
#endif

	for (auto i = 0U; i < count; ++i) {
		auto tinfo = (struct kinfo_proc *)procinfo_buf + i;

#ifndef NDEBUG
		std::cout << "[*] " << i
			<< ": tid = " << tinfo->ki_tid
			<< ", runtime = " << tinfo->ki_runtime
			<< ", user time = " << timeval_to_long(tinfo->ki_rusage.ru_utime)
			<< ", sys time = " << timeval_to_long(tinfo->ki_rusage.ru_stime)
			<< std::endl;
#endif

		if (tinfo->ki_tid == ktid) {
			*utime = tinfo->ki_rusage.ru_utime;
			*stime = tinfo->ki_rusage.ru_stime;
			break;
		}
	}

	free(procinfo_buf);
}