#include <string.h>
#include <stdlib.h>
#include <systemd/sd-bus.h>

#include "main.h"
#include "server.h"
#include "systemd.h"

#define SYSTEMD_DBUS_SERVICE		"org.freedesktop.systemd1"
#define SYSTEMD_DBUS_INTERFACE		"org.freedesktop.systemd1.Unit"
#define SYSTEMD_DBUS_PATH_PREFIX	"/org/freedesktop/systemd1/unit/"

static inline char
tohex(uint8_t val)
{
	static const char hex[] = "0123456789abcdef";

	return hex[val & 0x0f];
}

/*
 * Creates an escaped D-Bus object path for a given systemd service
 *
 * Escaping rules are documented here:
 * https://dbus.freedesktop.org/doc/dbus-specification.html
 *
 * Essentially, everyting but a-z, A-Z, 0-9 is replaced by _xx where xx is
 * the hexadecimal value of the character.
 *
 * Example: minecraft@world1.service -> minecraft_40world1_2eservice
 */
char *
systemd_object_path(const char *service)
{
	char *r;
	char *d;
	const char *s;

	assert_return(service && !empty_str(service), NULL);

	r = zmalloc(STRLEN(SYSTEMD_DBUS_PATH_PREFIX) + strlen(service) * 3 + 1);
	if (!r)
		return NULL;

	memcpy(r, SYSTEMD_DBUS_PATH_PREFIX, STRLEN(SYSTEMD_DBUS_PATH_PREFIX));
	d = r + STRLEN(SYSTEMD_DBUS_PATH_PREFIX);

	for (s = service; *s; s++) {
		if ((*s >= 'a' && *s <= 'z') ||
		    (*s >= 'A' && *s <= 'Z') ||
		    (*s >= '0' && *s <= '9')) {
			*(d++) = *s;
			continue;
		}

		*(d++) = '_';
		*(d++) = tohex(*s >> 4);
		*(d++) = tohex(*s);
	}

	*d = '\0';
	return r;
}

void
systemd_delete()
{
       	assert_return_silent(cfg->sd_bus);

        sd_bus_unref(cfg->sd_bus);
	cfg->sd_bus = NULL;
}

static sd_bus *
get_bus()
{
	int r;

	if (cfg->sd_bus_failed)
		return NULL;

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

	return cfg->sd_bus;
}

/*
 * Check if a systemd service is running.
 *
 * This is equivalent to (assuming service minecraft@world1):
 *   gdbus call --session 
 *	--dest org.freedesktop.systemd1 
 *	--object-path /org/freedesktop/systemd1/unit/minecraft_40world1_2eservice
 *	--method org.freedesktop.DBus.Properties.Get
 *		"org.freedesktop.systemd1.Unit" 
 *		"ActiveState"
 */
bool
systemd_service_running(struct server *server)
{
	sd_bus *bus = get_bus();
        sd_bus_error error = SD_BUS_ERROR_NULL;
	char *status = NULL;
	bool running = false;
	int r;

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

	r = sd_bus_get_property_string(bus,
				       SYSTEMD_DBUS_SERVICE,
				       server->systemd_obj,
				       SYSTEMD_DBUS_INTERFACE,
				       "ActiveState",
				       &error,
				       &status);
        if (r < 0) {
                error("failed to get status for service %s (%s): %s",
		      server->systemd_service, server->systemd_obj, error.message);
		goto out;
        }

	if (streq(status, "active")) {
		running = true;
		debug(DBG_SYSD, "systemd service %s (%s) is active",
		      server->systemd_service, server->systemd_obj);
	} else
		debug(DBG_SYSD, "systemd service %s (%s) is not active",
		      server->systemd_service, server->systemd_obj);

out:
	free(status);
        sd_bus_error_free(&error);
	return running;
}

static bool
systemd_service_action(struct server *server, 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(server && bus && server->systemd_service && server->systemd_obj && action, false);

        r = sd_bus_call_method(bus,
			       SYSTEMD_DBUS_SERVICE,
			       server->systemd_obj,
			       SYSTEMD_DBUS_INTERFACE,
			       action,
			       &error,
			       &m,
			       "s",
			       "fail");
        if (r < 0) {
                error("failed to perform action %s on systemd service %s: %s",
		      action, server->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, server->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 minecraft@world1):
 *   gdbus call --session 
 *	--dest org.freedesktop.systemd1 
 *	--object-path /org/freedesktop/systemd1/unit/minecraft_40world1_2eservice
 *	--method org.freedesktop.systemd1.Unit.Stop "fail"
 */
bool
systemd_service_stop(struct server *server)
{
	assert_return(server, false);

	return systemd_service_action(server, "Stop");
}

/*
 * Start systemd service.
 *
 * This is equivalent to (assuming service minecraft@world1):
 *   gdbus call --session 
 *	--dest org.freedesktop.systemd1 
 *	--object-path /org/freedesktop/systemd1/unit/minecraft_40world1_2eservice
 *	--method org.freedesktop.systemd1.Unit.Start "fail"
 */
bool
systemd_service_start(struct server *server)
{
	assert_return(server, false);

	return systemd_service_action(server, "Start");
}