#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_service_object_path(struct cfg *cfg, const char *service)
{
	char *r;
	char *d;
	const char *s;

	if (empty_str(service)) {
		fprintf(stderr, "%s: called with NULL arg\n", __func__);
		return NULL;
	}

	r = malloc(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(struct cfg *cfg)
{
	if (!cfg->sd_bus)
		return;

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

static sd_bus *
get_bus(struct cfg *cfg)
{
	int r;

	if (cfg->sd_bus_failed)
		return NULL;

	if (!cfg->sd_bus) {
		r = sd_bus_open_user(&cfg->sd_bus);
		if (r < 0) {
			fprintf(stderr, "Failed to connect to user system bus: %s\n", 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 cfg *cfg, struct server *server)
{
	sd_bus *bus = get_bus(cfg);
        sd_bus_error error = SD_BUS_ERROR_NULL;
	char *status = NULL;
	int r;
	bool running = false;

	if (!bus || !server->systemd_service || !server->systemd_obj)
		return false;

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

	if (!strcmp(status, "active")) {
		running = true;
		fprintf(stderr, "Systemd service %s (%s) is active\n",
			server->systemd_service, server->systemd_obj);
	} else
		fprintf(stderr, "Systemd service %s (%s) is not active\n",
			server->systemd_service, server->systemd_obj);

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

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

	if (!bus || !server->systemd_service || !server->systemd_obj || !action)
		return false;

        r = sd_bus_call_method(bus,
			       SYSTEMD_DBUS_SERVICE,
			       server->systemd_obj,
			       SYSTEMD_DBUS_INTERFACE,
			       action,
			       &error,
			       &m,
			       "s",
			       "fail");
        if (r < 0) {
                fprintf(stderr, "Failed to perform action %s on systemd service %s: %s\n",
			action, server->systemd_service, error.message);
		goto out;
        }

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

        fprintf(stderr, "Queued %s on service %s as %s\n",
		action, server->systemd_service, path);
	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 cfg *cfg, struct server *server)
{
	return systemd_service_action(cfg, 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 cfg *cfg, struct server *server)
{
	return systemd_service_action(cfg, server, "Start");
}


#if 0




int main(int argc, char *argv[]) {
        sd_bus_error error = SD_BUS_ERROR_NULL;
        sd_bus_message *m = NULL;
        sd_bus *bus = NULL;
        const char *path;
        int r;

        /* Connect to the system bus */
        r = sd_bus_open_user(&bus);
        if (r < 0) {
                fprintf(stderr, "Failed to connect to system bus: %s\n", strerror(-r));
                goto finish;
        }

        /* Issue the method call and store the respons message in m */
        r = sd_bus_call_method(bus,
                               "org.freedesktop.systemd1",           /* service to contact */
                               "/org/freedesktop/systemd1",          /* object path */
                               "org.freedesktop.systemd1.Manager",   /* interface name */
                               "StartUnit",                          /* method name */
                               &error,                               /* object to return error in */
                               &m,                                   /* return message on success */
                               "ss",                                 /* input signature */
                               "apa.service",                       /* first argument */
                               "fail");                           /* second argument */
        if (r < 0) {
                fprintf(stderr, "Failed to issue method call: %s\n", error.message);
                goto finish;
        }

        /* Parse the response message */
        r = sd_bus_message_read(m, "o", &path);
        if (r < 0) {
                fprintf(stderr, "Failed to parse response message: %s\n", strerror(-r));
		goto finish;
        }
        printf("Queued service job as %s.\n", path);

        sd_bus_error_free(&error);
        sd_bus_message_unref(m);
        error = SD_BUS_ERROR_NULL;
        m = NULL;

	/*
	   gdbus call --session
	   --dest org.freedesktop.systemd1 
	   --object-path /org/freedesktop/systemd1/unit/myapa_40local2_2eservice 
	   --method org.freedesktop.systemd1.Unit.Start "fail"

	   gdbus introspect --session
	   --dest org.freedesktop.systemd1
	   --object-path /org/freedesktop/systemd1/unit/myapa_40local_2eservice

	   gdbus call --session 
	   --dest org.freedesktop.systemd1 
	   --object-path /org/freedesktop/systemd1/unit/myapa_40basker_2eservice
	   --method org.freedesktop.DBus.Properties.Get
	   "org.freedesktop.systemd1.Unit" 
	   "ActiveState"
	   */
	char *res;
	r = sd_bus_get_property_string(bus,
				       "org.freedesktop.systemd1",
				       "/org/freedesktop/systemd1/unit/apa_2eservice",
				       "org.freedesktop.systemd1.Unit",
				       "ActiveState",
				       &error,
				       &res);
        if (r < 0) {
                fprintf(stderr, "Failed to issue prop call: %s\n", error.message);
                goto finish;
        }

	fprintf(stderr, "RESULT: %s\n", res);
/*
	int sd_bus_get_property_string(sd_bus *bus,
				       const char *destination,
				       const char *path,
				       const char *interface,
				       const char *member,
				       sd_bus_error *ret_error,
				       char **ret);
				       */
/*
finish:
        sd_bus_error_free(&error);
        sd_bus_message_unref(m);
        sd_bus_unref(bus);
	*/

finish:
        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}
#endif