#include <config.h>

#include <sys/types.h>

#include <locale.h>
#include <libintl.h>
#include <pthread.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include <security/pam_appl.h>

#include <gdk/gdk.h>
#include <gdk/gdkx.h>
#include <gtk/gtk.h>

#include <X11/Xlib.h>


#define _(s) gettext(s)
#define DEBUG(args...) syslog(LOG_NOTICE, args)


enum lock_state {
	LOCKED, UNLOCKING, LOGOUT
};


static enum lock_state state = LOCKED;

static GtkWidget *window, *unlockWindow, *lockLabel, *promptEntry, *messageLabel, *logoutButton, *unlockButton;
static gboolean enablePromptEntry = TRUE, enableLogoutButton = FALSE, enableUnlockButton = TRUE;

static char *username;
static char *logoutCommand = NULL;
static int logoutTime = 0;


static Atom atom;
static Window selection;


static gboolean do_grab_devices(gpointer user_data) {
	DEBUG("do_grab_devices");

	gtk_window_present(GTK_WINDOW(window));

	GdkDeviceManager *deviceManager = gdk_display_get_device_manager(gdk_display_get_default());
	GList *devices = gdk_device_manager_list_devices(deviceManager, GDK_DEVICE_TYPE_MASTER);

	gboolean error = FALSE;

	for (; devices; devices = g_list_next(devices)) {
		GdkDevice *device = devices->data;

		if (gdk_device_grab(device, gtk_widget_get_window(window), GDK_OWNERSHIP_APPLICATION, TRUE, GDK_ALL_EVENTS_MASK, NULL, GDK_CURRENT_TIME) != GDK_GRAB_SUCCESS)
			error = TRUE;
	}

	g_list_free(devices);

	return error;
}

static void grab_devices(void) {
	if (do_grab_devices(NULL))
		g_timeout_add_seconds(1, do_grab_devices, NULL);
}

static void update(void) {
	gboolean locked = (state == LOCKED);

	gtk_widget_set_sensitive(promptEntry, enablePromptEntry && locked);
	gtk_widget_set_sensitive(logoutButton, enableLogoutButton && locked);
	gtk_widget_set_sensitive(unlockButton, enableUnlockButton && locked);
}

static gboolean do_update_logout_time(gpointer user_data) {
	gboolean ret = FALSE;
	char *escaped_username = g_markup_escape_text(username, -1);
	char *message;

	if (!logoutCommand) {
		message = g_strdup_printf(_("This computer is currently locked by the user <i>%s</i>."), escaped_username);
		enableLogoutButton = FALSE;
	}
	else if (logoutTime > 0) {
		message = g_strdup_printf(_("This computer is currently locked by the user <i>%s</i>.\nThe user can be logged out in %02u:%02u minutes."), escaped_username, logoutTime/60, logoutTime%60);
		enableLogoutButton = FALSE;
		ret = TRUE;
		logoutTime--;
	}
	else {
		message = g_strdup_printf(_("This computer is currently locked by the user <i>%s</i>.\nThe user can be logged out now."), escaped_username);
		enableLogoutButton = TRUE;
	}

	gtk_label_set_markup(GTK_LABEL(lockLabel), message);
	g_free(message);

	update();

	return ret;
}

static void update_logout_time() {
	if (do_update_logout_time(NULL))
		g_timeout_add_seconds(1, do_update_logout_time, NULL);
}

static void lock(void) {
	if (state != LOCKED)
		return;

	DEBUG("lock");

	update();
	grab_devices();
	gtk_widget_grab_focus(promptEntry);
}

static int ulock_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) {
	char *password = appdata_ptr;

	*resp = calloc(num_msg, sizeof(struct pam_response));
	int i;
	for (i = 0; i < num_msg; i++) {
		if (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF)
			resp[i]->resp = strdup(password);
	}

	return 0;
}

static gboolean try_unlock_return(gpointer message) {
	DEBUG("try_unlock_return");

	if (message) {
		state = LOCKED;
		gtk_entry_set_text(GTK_ENTRY(promptEntry), "");
		gtk_label_set_label(GTK_LABEL(messageLabel), message);
		lock();
	}
	else {
		gtk_main_quit();
	}

	return FALSE;
}

/* this thread must not access any GTK resources */
static void* try_unlock_thread(void *arg) {
	const struct pam_conv conv = {.conv = ulock_conv, .appdata_ptr = arg};

	pam_handle_t *handle = NULL;
	int ret = pam_start("login", username, &conv, &handle);

	if (!ret)
		ret = pam_authenticate(handle, 0);

	const char *message = NULL;
	if (ret)
		message = pam_strerror(handle, ret);

	pam_end(handle, ret);

	g_idle_add(try_unlock_return, (gpointer)message);

	free(arg);
	return NULL;
}

static void try_unlock(void) {
	if (state != LOCKED)
		return;

	DEBUG("try_unlock");

	state = UNLOCKING;
	update();
	gtk_label_set_label(GTK_LABEL(messageLabel), "");

	pthread_t thread;
	pthread_create(&thread, NULL, try_unlock_thread, strdup(gtk_entry_get_text(GTK_ENTRY(promptEntry))));
	pthread_detach(thread);
}

static void logout(void) {
	if (state != LOCKED)
		return;

	if (!logoutCommand)
		return;

	if (logoutTime > 0)
		return;

	DEBUG("logout");

	state = LOGOUT;
	update();

	system(logoutCommand);
}

static GdkFilterReturn xevent_filter(GdkXEvent *xevent, GdkEvent *event, gpointer data) {
	XEvent *ev = xevent;

	switch (ev->xany.type) {
	case MapNotify:
	case ConfigureNotify:
		if (ev->xany.window != gdk_x11_window_get_xid(gtk_widget_get_window(window)))
			gtk_window_present(GTK_WINDOW(window));
		break;

	case DestroyNotify:
		if (ev->xdestroywindow.window == selection)
			gtk_main_quit();
		break;

	default:
		break;
	}

	return GDK_FILTER_CONTINUE;
}

static void wait_for_selection(void) {
	DEBUG("wait_for_selection");

	GdkDisplay *display = gdk_display_get_default();
	Display *xdisplay = gdk_x11_display_get_xdisplay(display);
	gdk_x11_display_error_trap_push(display);

	XSelectInput(xdisplay, selection, StructureNotifyMask);

	if (gdk_x11_display_error_trap_pop(display))
		return;

	gtk_main();
}

static void create_lock_window(void) {
	window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

	gtk_widget_realize(window);
	gdk_window_add_filter(NULL, (GdkFilterFunc)xevent_filter, NULL);

	atom = gdk_x11_get_xatom_by_name("ULOCK");

	gdk_x11_grab_server();

	selection = XGetSelectionOwner(gdk_x11_get_default_xdisplay(), atom);
	if (selection == None)
		XSetSelectionOwner(gdk_x11_get_default_xdisplay(), atom, gdk_x11_window_get_xid(gtk_widget_get_window(window)), CurrentTime);

	gdk_x11_ungrab_server();

	if (selection != None) {
		wait_for_selection();
		exit(0);
	}

	gtk_window_set_decorated(GTK_WINDOW(window), FALSE);
	gtk_window_set_skip_taskbar_hint(GTK_WINDOW(window), TRUE);
	gtk_window_set_skip_pager_hint(GTK_WINDOW(window), TRUE);
	gtk_window_set_keep_above(GTK_WINDOW(window), TRUE);
	gtk_window_fullscreen(GTK_WINDOW(window));

	GtkWidget *overlay = gtk_overlay_new();
	gtk_container_add(GTK_CONTAINER(window), overlay);

	GtkWidget *bg = gtk_image_new_from_file(DATA_DIR "/bg.svg");
	gtk_container_add(GTK_CONTAINER(overlay), bg);

	GtkBuilder *builder = gtk_builder_new();

	if (!gtk_builder_add_from_file(builder, DATA_DIR "/unlock.ui", NULL))
		exit(1);

	unlockWindow = GTK_WIDGET(gtk_builder_get_object(builder, "unlock_window"));
	lockLabel = GTK_WIDGET(gtk_builder_get_object(builder, "lock_label"));
	promptEntry = GTK_WIDGET(gtk_builder_get_object(builder, "prompt_entry"));
	messageLabel = GTK_WIDGET(gtk_builder_get_object(builder, "message_label"));
	logoutButton = GTK_WIDGET(gtk_builder_get_object(builder, "logout_button"));
	unlockButton = GTK_WIDGET(gtk_builder_get_object(builder, "unlock_button"));

	gtk_overlay_add_overlay(GTK_OVERLAY(overlay), unlockWindow);

	gtk_widget_show_all(overlay);

	gtk_entry_set_text(GTK_ENTRY(promptEntry), "");
	gtk_label_set_label(GTK_LABEL(messageLabel), "");

	g_signal_connect(promptEntry, "activate", G_CALLBACK(try_unlock), NULL);
	g_signal_connect(unlockButton, "clicked", G_CALLBACK(try_unlock), NULL);
	g_signal_connect(logoutButton, "clicked", G_CALLBACK(logout), NULL);
	g_signal_connect(window, "map-event", G_CALLBACK(lock), NULL);
	g_signal_connect(window, "delete-event", G_CALLBACK(gtk_true), NULL);

	XSelectInput(gdk_x11_get_default_xdisplay(), gdk_x11_get_default_root_xwindow(), SubstructureNotifyMask);

	update_logout_time();
}

static void get_username(void) {
	struct passwd *passwd = getpwuid(getuid());
	if (!passwd)
		exit(2);

	username = strdup(passwd->pw_name);
}

static void load_config(void) {
	GKeyFile *keyFile = g_key_file_new();
	if (!g_key_file_load_from_file(keyFile, CONFIG_FILE, G_KEY_FILE_NONE, NULL))
		return;

	gchar *theme = g_key_file_get_string(keyFile, "ulock", "theme", NULL);
	if (theme)
		gtk_settings_set_string_property(gtk_settings_get_default(), "gtk-theme-name", theme, "ulock");

	logoutTime = g_key_file_get_integer(keyFile, "ulock", "logout_timeout", NULL);

	gchar *logoutCommandConfig = g_key_file_get_string(keyFile, "ulock", "logout_command", NULL);
	if (logoutCommandConfig)
		logoutCommand = strdup(logoutCommandConfig);

	g_key_file_free(keyFile);
}

int main(int argc, char *argv[]) {
	get_username();

	setlocale(LC_ALL, "");
	bindtextdomain("ulock", PREFIX "/share/locale");
	textdomain("ulock");

	openlog("ulock", LOG_PID, LOG_DAEMON);

	gtk_init(&argc, &argv);
	load_config();

	create_lock_window();
	gtk_widget_show(window);

	gtk_main();

	return 0;
}