/* SPDX-License-Identifier: GPL-2.0 */
#include <string.h>
#include <stdlib.h>
#include <systemd/sd-bus.h>
#include <errno.h>

#include "utils.h"
#include "config-parser.h"
#include "systemd.h"

static sd_bus *bus = NULL;
static bool bus_failed = false;

void systemd_delete()
{
	assert_return_silent(bus);

	sd_bus_unref(bus);
	bus = NULL;
	bus_failed = false;
}

static sd_bus *get_bus()
{
	int r;

	if (bus_failed)
		return NULL;

	if (!bus) {
		r = sd_bus_open_user(&bus);
		if (r < 0) {
			error("failed to connect to user system bus: %s",
			      strerror(-r));
			bus_failed = true;
			return NULL;
		}
	}

	return bus;
}

/*
 * Check if a systemd service is running.
 *
 * This is equivalent to (assuming service mc@world1):
 *   gdbus call --session
 *	--dest org.freedesktop.systemd1
 *	--object-path /org/freedesktop/systemd1/unit/mc_40world1_2eservice
 *	--method org.freedesktop.DBus.Properties.Get
 *		"org.freedesktop.systemd1.Unit"
 *		"ActiveState"
 */
bool systemd_service_running(struct server_config *scfg, const char **error)
{
	sd_bus *bus = get_bus();
	sd_bus_error sderror = SD_BUS_ERROR_NULL;
	char *status = NULL;
	bool running = false;
	int r;

	assert_return(bus && error && scfg && scfg->systemd_service &&
		      scfg->systemd_obj, false);

again:
	r = sd_bus_get_property_string(bus, SYSTEMD_DBUS_SERVICE,
				       scfg->systemd_obj,
				       SYSTEMD_DBUS_INTERFACE, "ActiveState",
				       &sderror, &status);
	if (r < 0) {
		if (sd_bus_error_get_errno(&sderror) == EINTR)
			goto again;

		debug(DBG_SYSD, "failed to get status for server %s (%s): %s",
		      scfg->systemd_service, scfg->systemd_obj, sderror.message);
		*error = "failed to get service status";

	} else if (streq(status, "active")) {
		running = true;
		debug(DBG_SYSD, "systemd service %s (%s) is active",
		      scfg->systemd_service, scfg->systemd_obj);

	} else {
		debug(DBG_SYSD, "systemd service %s (%s) is not active (%s)",
		      scfg->systemd_service, scfg->systemd_obj, status);
		*error = "service not active";
	}

	free(status);
	sd_bus_error_free(&sderror);
	return running;
}

static bool systemd_service_action(struct server_config *scfg,
				   const char *action)
{
	sd_bus_error error = SD_BUS_ERROR_NULL;
	sd_bus_message *m = NULL;
	sd_bus *bus = get_bus();
	const char *path;
	bool performed = false;
	int r;

	assert_return(bus && scfg && scfg->systemd_service &&
		      scfg->systemd_obj && action, false);

again:
	r = sd_bus_call_method(bus, SYSTEMD_DBUS_SERVICE, scfg->systemd_obj,
			       SYSTEMD_DBUS_INTERFACE, action, &error, &m, "s",
			       "fail");
	if (r < 0) {
		if (sd_bus_error_get_errno(&error) == EINTR)
			goto again;

		error("failed to perform action %s on systemd service %s: %s",
		      action, scfg->systemd_service, error.message);
		goto out;
	}

	r = sd_bus_message_read(m, "o", &path);
	if (r < 0) {
		error("failed to parse response message: %s", strerror(-r));
		goto out;
	}

	verbose("action %s queued for service %s", action,
		scfg->systemd_service);
	performed = true;

out:
	sd_bus_error_free(&error);
	sd_bus_message_unref(m);
	return performed;
}

/*
 * Stop systemd service.
 *
 * This is equivalent to (assuming service mc@world1):
 *   gdbus call --session
 *	--dest org.freedesktop.systemd1
 *	--object-path /org/freedesktop/systemd1/unit/mc_40world1_2eservice
 *	--method org.freedesktop.systemd1.Unit.Stop "fail"
 */
bool systemd_service_stop(struct server_config *scfg)
{
	assert_return(scfg, false);

	return systemd_service_action(scfg, "Stop");
}

/*
 * Start systemd service.
 *
 * This is equivalent to (assuming service mc@world1):
 *   gdbus call --session
 *	--dest org.freedesktop.systemd1
 *	--object-path /org/freedesktop/systemd1/unit/mc_40world1_2eservice
 *	--method org.freedesktop.systemd1.Unit.Start "fail"
 */
bool systemd_service_start(struct server_config *scfg)
{
	assert_return(scfg, false);

	return systemd_service_action(scfg, "Start");
}