/*
 * Copyright (C) 2013-2024  Eugen Wissner <belka@caraus.de>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <filesystem>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/stat.h>

#include "slack-timedate.h"

static void slack_method_call (GDBusConnection *connection, const gchar *sender, const gchar *object_path, const gchar *interface_name, const gchar *method_name, GVariant *parameters, GDBusMethodInvocation *invocation, gpointer user_data) {
	gchar *timezone, *response;
	gboolean user_interaction, relative, is_localtime, use_ntp;
	gint64 usec_utc;

	// Set time zone
	if (g_strcmp0 (method_name, "SetTimezone") == 0) {
		g_variant_get (parameters, "(&sb)", &timezone, &user_interaction);

		if (slack_set_timezone (timezone)) g_dbus_method_invocation_return_value (invocation,
				NULL);
		else g_dbus_method_invocation_return_error (invocation,
				G_IO_ERROR,
				G_IO_ERROR_FAILED,
				"Write operation failed");

		g_free (timezone);
    } else if (g_strcmp0 (method_name, "SetTime") == 0) {
		g_variant_get (parameters, "(xbb)", &usec_utc, &relative, &user_interaction);

		// Set time
		//if (!slack_set_time (usec_utc, slack_get_is_localtime ())) {
		if (slack_set_time(usec_utc, relative))
        {
            g_dbus_method_invocation_return_value(invocation, NULL);
        }
		else
        {
            g_dbus_method_invocation_return_error(invocation, G_IO_ERROR, G_IO_ERROR_FAILED,
                    "Failed to set system clock");
        }
    } else if (g_strcmp0 (method_name, "SetNTP") == 0) {
		g_variant_get (parameters, "(bb)", &use_ntp, &user_interaction);

		// Enable NTP
		if (slack_set_ntp (use_ntp)) g_dbus_method_invocation_return_value (invocation,
				NULL);
		else g_dbus_method_invocation_return_error (invocation,
				G_IO_ERROR,
				G_IO_ERROR_FAILED,
				"Error enabling NTP");
	}
	return;
}

static GVariant *slack_get_property (GDBusConnection *connection, const gchar *sender, const gchar *object_path, const gchar *interface_name, const gchar *prop_name, GError **slack_err, gpointer user_data) {
	if (g_strcmp0 ("Timezone", prop_name) == 0) {
		return g_variant_new_string (slack_get_timezone ());
	} if (g_strcmp0 ("LocalRTC", prop_name) == 0) {
		return g_variant_new_boolean (slack_get_is_localtime ());
	} if (g_strcmp0 ("NTP", prop_name) == 0) {
		return g_variant_new_boolean (slack_get_ntp ());
	}
	return NULL;
}

static void on_timedate_acquired (GDBusConnection *connection, const gchar *name, gpointer user_data) {
	guint registration_id;
	GDBusNodeInfo *introspection_data;
	GError *slack_err;
	const GDBusInterfaceVTable interface_vtable = {
		slack_method_call,
		slack_get_property,
		NULL
	};

	slack_err = NULL;
	introspection_data = g_dbus_node_info_new_for_xml (INTROSPECTION_XML, &slack_err);
	if (introspection_data == NULL)
		g_error ("Failed to parse D-Bus introspection XML: %s\n", slack_err->message);

	slack_err = NULL;
	registration_id = g_dbus_connection_register_object (connection,
			BUS_PATH,
			introspection_data->interfaces[0],
			&interface_vtable,
			NULL,
			NULL,
			&slack_err);

	if (registration_id <= 0) {
		g_critical ("Failed to register callbacks for the exported object with the D-Bus interface: %s\n", slack_err->message);
		g_error_free (slack_err);
	}

	g_dbus_node_info_unref (introspection_data);
}

static void on_timedate_lost (GDBusConnection *connection, const gchar *name, gpointer user_data) {
	g_warning ("Failed to acquire the service %s.\n", name);
	exit (1);
}

gboolean timeout_callback (Glib::RefPtr<Glib::MainLoop> loop2quit) {
	loop2quit->quit();
	return false;
}

int main(int argc, char **argv)
{
	guint owner_id = g_bus_own_name (G_BUS_TYPE_SYSTEM,
			BUS_NAME,
			static_cast<GBusNameOwnerFlags>(G_BUS_NAME_OWNER_FLAGS_ALLOW_REPLACEMENT | G_BUS_NAME_OWNER_FLAGS_REPLACE),
			on_timedate_acquired,
			NULL,
			on_timedate_lost,
			NULL,
			NULL);
    Glib::RefPtr<Glib::MainLoop> loop = Glib::MainLoop::create(false);

    Glib::signal_timeout().connect_seconds(sigc::bind(&timeout_callback, loop), DEFAULT_EXIT_SEC);
	loop->run();

	g_bus_unown_name (owner_id);

	return EXIT_SUCCESS;
}


gchar *slack_get_timezone () {
	gchar *zone_copied_from, *zone;

	zone_copied_from = g_file_read_link ("/etc/localtime-copied-from", NULL);
	if (zone_copied_from == NULL) return NULL;

	zone = g_strdup (zone_copied_from + strlen ("/usr/share/zoneinfo/") * sizeof (gchar));
	g_free (zone_copied_from);

	return zone;
}

gboolean slack_set_timezone (gchar *zone) {
	gchar *zone_file;
	GFile *etc_localtime, *localtime_link, *g_zone_file;

	zone_file = g_strconcat ("/usr/share/zoneinfo/", zone, NULL);
	if (Glib::file_test(zone_file, Glib::FILE_TEST_IS_REGULAR))
    {
		etc_localtime = g_file_new_for_path ("/etc/localtime");
		localtime_link = g_file_new_for_path ("/etc/localtime-copied-from");
		g_zone_file = g_file_new_for_path (zone_file);

		if (!g_file_copy (g_zone_file, etc_localtime, G_FILE_COPY_OVERWRITE, NULL, NULL, NULL, NULL)) {
			return FALSE;
		}

		if (!g_file_delete (localtime_link, NULL, NULL)) {
			return FALSE;
		}
		if (!g_file_make_symbolic_link (localtime_link, zone_file, NULL, NULL)) {
			return FALSE;
		}

		g_free (zone_file);
		g_object_unref (etc_localtime);
		g_object_unref (localtime_link);
		g_object_unref (g_zone_file);

        return true;
	}
    return false;
}

gboolean slack_set_time(gint64 seconds_since_epoch, gboolean relative)
{
    timespec ts;

    if (relative)
    {
        if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
        {
            return FALSE;
        }
        ts.tv_sec += static_cast<time_t>(seconds_since_epoch / USEC_PER_SEC);
        ts.tv_nsec += (seconds_since_epoch % USEC_PER_SEC) * NSEC_PER_USEC;

        if (ts.tv_nsec < 0)
        {
            --ts.tv_sec;
            ts.tv_nsec += USEC_PER_SEC;
        }
    }
    else
    {
        ts.tv_sec = static_cast<time_t>(seconds_since_epoch / USEC_PER_SEC);
        ts.tv_nsec = (seconds_since_epoch % USEC_PER_SEC) * NSEC_PER_USEC;
    }
    return clock_settime (CLOCK_REALTIME, &ts) == 0;
}

gboolean slack_get_is_localtime () {
	FILE *fh;
	char time_str[10]; // "localtime" is longer than "UTC" and has 9 letters + \0
	gboolean is_localtime;

	is_localtime = FALSE;

	fh = fopen ("/etc/hardwareclock", "r");
	if (fh == NULL) return FALSE;
	while (fgets (time_str, 10, fh)) {
		if (!g_strcmp0 (time_str, "localtime")) {
			is_localtime = TRUE;
			break;
		}
	}

	fclose (fh);
	return is_localtime;
}

gboolean slack_get_ntp()
{
	return Glib::file_test("/etc/rc.d/rc.ntpd", Glib::FileTest::FILE_TEST_IS_EXECUTABLE);
}

gboolean slack_set_ntp(gboolean xntp)
{
    std::filesystem::perms rc_mode = std::filesystem::perms::owner_read | std::filesystem::perms::owner_write
        | std::filesystem::perms::group_read | std::filesystem::perms::others_read;

    if (xntp)
    {
        rc_mode |= std::filesystem::perms::owner_exec
            | std::filesystem::perms::group_exec | std::filesystem::perms::others_exec;
        g_message("Please don't forget to configure the NTP daemon");

        /* It doesn't matter if fails.
         * The ntpdate command is considered obsolete, but "orthodox" ntpd -g
         * will fail if your system clock is off for more than half an hour. */
        g_spawn_command_line_async("/usr/sbin/ntpdate pool.ntp.org", NULL);
    }
    if (Glib::file_test("/etc/rc.d/rc.ntpd", Glib::FileTest::FILE_TEST_IS_REGULAR))
    {
        std::error_code ec;
        std::filesystem::permissions("/etc/rc.d/rc.ntpd", rc_mode, ec);
        return !ec;
    }
    else
    {
        g_error("The NTP daemon isn't installed");
        return false;
    }
}