/*
 *  Copyright (C) 2013 IBM Corporation
 *
 *  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; version 2 of the License.
 *
 *  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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include <pb-config/pb-config.h>
#include <talloc/talloc.h>
#include <types/types.h>
#include <log/log.h>
#include <i18n/i18n.h>

#include "nc-cui.h"
#include "nc-config.h"
#include "nc-widgets.h"

#define N_FIELDS	25

extern const char *config_help_text;

enum autoboot_type {
	AUTOBOOT_ANY,
	AUTOBOOT_ONE,
	AUTOBOOT_DISABLED,
};

enum net_conf_type {
	NET_CONF_TYPE_DHCP_ALL,
	NET_CONF_TYPE_DHCP_ONE,
	NET_CONF_TYPE_STATIC,
};

struct config_screen {
	struct nc_scr		scr;
	struct cui		*cui;
	struct nc_widgetset	*widgetset;
	WINDOW			*pad;

	bool			exit;
	bool			show_help;
	void			(*on_exit)(struct cui *);

	int			scroll_y;

	int			label_x;
	int			field_x;
	int			network_config_y;

	enum net_conf_type	net_conf_type;
	enum autoboot_type	autoboot_type;

	struct {
		struct nc_widget_select		*autoboot_f;
		struct nc_widget_label		*autoboot_l;
		struct nc_widget_select		*boot_device_f;
		struct nc_widget_textbox	*timeout_f;
		struct nc_widget_label		*timeout_l;
		struct nc_widget_label		*timeout_help_l;

		struct nc_widget_label		*network_l;
		struct nc_widget_select		*network_f;

		struct nc_widget_label		*iface_l;
		struct nc_widget_select		*iface_f;
		struct nc_widget_label		*ip_addr_l;
		struct nc_widget_textbox	*ip_addr_f;
		struct nc_widget_label		*ip_mask_l;
		struct nc_widget_textbox	*ip_mask_f;
		struct nc_widget_label		*ip_addr_mask_help_l;
		struct nc_widget_label		*gateway_l;
		struct nc_widget_textbox	*gateway_f;
		struct nc_widget_label		*gateway_help_l;
		struct nc_widget_label		*dns_l;
		struct nc_widget_textbox	*dns_f;
		struct nc_widget_label		*dns_dhcp_help_l;
		struct nc_widget_label		*dns_help_l;

		struct nc_widget_button		*ok_b;
		struct nc_widget_button		*help_b;
		struct nc_widget_button		*cancel_b;
	} widgets;
};

static struct config_screen *config_screen_from_scr(struct nc_scr *scr)
{
	struct config_screen *config_screen;

	assert(scr->sig == pb_config_screen_sig);
	config_screen = (struct config_screen *)
		((char *)scr - (size_t)&((struct config_screen *)0)->scr);
	assert(config_screen->scr.sig == pb_config_screen_sig);
	return config_screen;
}

static void pad_refresh(struct config_screen *screen)
{
	int y, x, rows, cols;

	getmaxyx(screen->scr.sub_ncw, rows, cols);
	getbegyx(screen->scr.sub_ncw, y, x);

	prefresh(screen->pad, screen->scroll_y, 0, y, x, rows, cols);
}

static void config_screen_process_key(struct nc_scr *scr, int key)
{
	struct config_screen *screen = config_screen_from_scr(scr);
	bool handled;

	handled = widgetset_process_key(screen->widgetset, key);

	if (!handled) {
		switch (key) {
		case 'x':
		case 27: /* esc */
			screen->exit = true;
			break;
		case 'h':
			screen->show_help = true;
			break;
		}
	}

	if (screen->exit) {
		screen->on_exit(screen->cui);

	} else if (screen->show_help) {
		screen->show_help = false;
		cui_show_help(screen->cui, _("System Configuration"),
				config_help_text);

	} else if (handled) {
		pad_refresh(screen);
	}
}

static void config_screen_resize(struct nc_scr *scr)
{
	struct config_screen *screen = config_screen_from_scr(scr);
	(void)screen;
}

static int config_screen_post(struct nc_scr *scr)
{
	struct config_screen *screen = config_screen_from_scr(scr);
	widgetset_post(screen->widgetset);
	nc_scr_frame_draw(scr);
	redrawwin(scr->main_ncw);
	wrefresh(screen->scr.main_ncw);
	pad_refresh(screen);
	return 0;
}

static int config_screen_unpost(struct nc_scr *scr)
{
	struct config_screen *screen = config_screen_from_scr(scr);
	widgetset_unpost(screen->widgetset);
	return 0;
}

struct nc_scr *config_screen_scr(struct config_screen *screen)
{
	return &screen->scr;
}

static int screen_process_form(struct config_screen *screen)
{
	const struct system_info *sysinfo = screen->cui->sysinfo;
	enum net_conf_type net_conf_type;
	struct interface_config *iface;
	struct config *config;
	char *str, *end;
	int rc, idx;

	config = config_copy(screen, screen->cui->config);

	screen->autoboot_type =
		widget_select_get_value(screen->widgets.autoboot_f);

	config->autoboot_enabled = screen->autoboot_type != AUTOBOOT_DISABLED;

	if (screen->autoboot_type == AUTOBOOT_ONE) {
		char mac[20], *uuid = NULL;

		/* if idx is -1 here, we have an unknown UUID selected.
		 * Otherwise, it's a blockdev index (idx <= n_blockdevs) or an
		 * interface index.
		 */
		idx = widget_select_get_value(screen->widgets.boot_device_f);
		if (idx >= (int)sysinfo->n_blockdevs) {
			struct interface_info *info = sysinfo->
				interfaces[idx - sysinfo->n_blockdevs];
			mac_str(info->hwaddr, info->hwaddr_size,
					mac, sizeof(mac));
			uuid = mac;
		} else if (idx != -1) {
			uuid = sysinfo->blockdevs[idx]->uuid;
		}

		if (uuid) {
			talloc_free(config->boot_device);
			config->boot_device = talloc_strdup(config, uuid);
		}
	}

	str = widget_textbox_get_value(screen->widgets.timeout_f);
	if (str) {
		unsigned long x;
		errno = 0;
		x = strtoul(str, &end, 10);
		if (!errno && end != str)
			config->autoboot_timeout_sec = x;
	}

	net_conf_type = widget_select_get_value(screen->widgets.network_f);

	/* if we don't have any network interfaces, prevent per-interface
	 * configuration */
	if (sysinfo->n_interfaces == 0)
		net_conf_type = NET_CONF_TYPE_DHCP_ALL;

	if (net_conf_type == NET_CONF_TYPE_DHCP_ALL) {
		config->network.n_interfaces = 0;

	} else {
		iface = talloc_zero(config, struct interface_config);
		config->network.n_interfaces = 1;
		config->network.interfaces = talloc_array(config,
				struct interface_config *, 1);
		config->network.interfaces[0] = iface;

		/* copy hwaddr (from the sysinfo interface data) to
		 * the configuration */
		idx = widget_select_get_value(screen->widgets.iface_f);
		memcpy(iface->hwaddr, sysinfo->interfaces[idx]->hwaddr,
				sizeof(iface->hwaddr));
	}

	if (net_conf_type == NET_CONF_TYPE_DHCP_ONE) {
		iface->method = CONFIG_METHOD_DHCP;
	}

	if (net_conf_type == NET_CONF_TYPE_STATIC) {
		char *ip, *mask, *gateway;

		ip = widget_textbox_get_value(screen->widgets.ip_addr_f);
		mask = widget_textbox_get_value(screen->widgets.ip_mask_f);
		gateway = widget_textbox_get_value(screen->widgets.gateway_f);

		if (!ip || !*ip || !mask || !*mask) {
			screen->scr.frame.status =
				_("No IP / mask values are set");
			nc_scr_frame_draw(&screen->scr);
			talloc_free(config);
			return -1;
		}

		iface->method = CONFIG_METHOD_STATIC;
		iface->static_config.address = talloc_asprintf(iface, "%s/%s",
				ip, mask);
		iface->static_config.gateway = talloc_strdup(iface, gateway);
	}

	str = widget_textbox_get_value(screen->widgets.dns_f);
	talloc_free(config->network.dns_servers);
	config->network.dns_servers = NULL;
	config->network.n_dns_servers = 0;

	if (str && strlen(str)) {
		char *dns, *tmp;
		int i;

		for (;;) {
			dns = strtok_r(str, " \t", &tmp);

			if (!dns)
				break;

			i = config->network.n_dns_servers++;
			config->network.dns_servers = talloc_realloc(config,
					config->network.dns_servers,
					const char *,
					config->network.n_dns_servers);
			config->network.dns_servers[i] =
				talloc_strdup(config, dns);

			str = NULL;
		}
	}

	rc = cui_send_config(screen->cui, config);
	talloc_free(config);

	if (rc)
		pb_log("cui_send_config failed!\n");
	else
		pb_debug("config sent!\n");

	return 0;
}

static void ok_click(void *arg)
{
	struct config_screen *screen = arg;
	if (screen_process_form(screen))
		/* errors are written to the status line, so we'll need
		 * to refresh */
		wrefresh(screen->scr.main_ncw);
	else
		screen->exit = true;
}

static void help_click(void *arg)
{
	struct config_screen *screen = arg;
	screen->show_help = true;
}

static void cancel_click(void *arg)
{
	struct config_screen *screen = arg;
	screen->exit = true;
}

static int layout_pair(struct config_screen *screen, int y,
		struct nc_widget_label *label,
		struct nc_widget *field)
{
	struct nc_widget *label_w = widget_label_base(label);
	widget_move(label_w, y, screen->label_x);
	widget_move(field, y, screen->field_x);
	return max(widget_height(label_w), widget_height(field));
}

static void config_screen_layout_widgets(struct config_screen *screen)
{
	struct nc_widget *wl, *wf, *wh;
	int y, x, help_x;
	bool show;

	y = 1;
	help_x = screen->field_x + 2 +
		widget_width(widget_textbox_base(screen->widgets.dns_f));

	y += layout_pair(screen, y, screen->widgets.autoboot_l,
			widget_select_base(screen->widgets.autoboot_f));

	wf = widget_select_base(screen->widgets.boot_device_f);
	if (screen->autoboot_type == AUTOBOOT_ONE) {
		widget_set_visible(wf, true);
		widget_move(wf, y, screen->field_x + 3);
		y += widget_height(wf);
	} else {
		widget_set_visible(wf, false);
	}

	y += 1;

	wf = widget_textbox_base(screen->widgets.timeout_f);
	wl = widget_label_base(screen->widgets.timeout_l);
	wh = widget_label_base(screen->widgets.timeout_help_l);
	if (screen->autoboot_type != AUTOBOOT_DISABLED) {
		widget_set_visible(wl, true);
		widget_set_visible(wf, true);
		widget_set_visible(wh, true);
		widget_move(wl, y, screen->label_x);
		widget_move(wf, y, screen->field_x);
		widget_move(wh, y, screen->field_x + widget_width(wf) + 1);
		y += 2;
	} else {
		widget_set_visible(wl, false);
		widget_set_visible(wf, false);
		widget_set_visible(wh, false);
	}

	y += layout_pair(screen, y, screen->widgets.network_l,
			widget_select_base(screen->widgets.network_f));

	y += 1;

	/* conditionally show iface select */
	wl = widget_label_base(screen->widgets.iface_l);
	wf = widget_select_base(screen->widgets.iface_f);

	show = screen->net_conf_type == NET_CONF_TYPE_DHCP_ONE ||
		screen->net_conf_type == NET_CONF_TYPE_STATIC;

	widget_set_visible(wl, show);
	widget_set_visible(wf, show);

	if (show)
		y += layout_pair(screen, y, screen->widgets.iface_l, wf) + 1;

	/* conditionally show static IP params */
	show = screen->net_conf_type == NET_CONF_TYPE_STATIC;

	wl = widget_label_base(screen->widgets.ip_addr_l);
	wf = widget_textbox_base(screen->widgets.ip_addr_f);
	widget_set_visible(wl, show);
	widget_set_visible(wf, show);
	x = screen->field_x + widget_width(wf) + 1;

	if (show)
		layout_pair(screen, y, screen->widgets.ip_addr_l, wf);

	wl = widget_label_base(screen->widgets.ip_mask_l);
	wf = widget_textbox_base(screen->widgets.ip_mask_f);
	widget_set_visible(wl, show);
	widget_set_visible(wf, show);

	if (show) {
		widget_move(wl, y, x);
		widget_move(wf, y, x + 2);
	}

	/* help for IP/mask */
	wh = widget_label_base(screen->widgets.ip_addr_mask_help_l);
	widget_set_visible(wh, show);
	if (show) {
		widget_move(wh, y, help_x);
		y++;
	}

	wl = widget_label_base(screen->widgets.gateway_l);
	wf = widget_textbox_base(screen->widgets.gateway_f);
	wh = widget_label_base(screen->widgets.gateway_help_l);
	widget_set_visible(wl, show);
	widget_set_visible(wf, show);
	widget_set_visible(wh, show);

	if (show) {
		layout_pair(screen, y, screen->widgets.gateway_l, wf);
		widget_move(wh, y, help_x);
		y++;
	}

	wh = widget_label_base(screen->widgets.dns_help_l);
	layout_pair(screen, y, screen->widgets.dns_l,
			widget_textbox_base(screen->widgets.dns_f));
	widget_move(wh, y, help_x);
	y++;

	/* we show the DNS/DHCP help if we're configuring DHCP */
	show = screen->net_conf_type != NET_CONF_TYPE_STATIC;
	wl = widget_label_base(screen->widgets.dns_dhcp_help_l);
	widget_set_visible(wl, show);
	if (show) {
		widget_move(wl, y, screen->field_x);
		y += 1;
	}

	y += 1;

	widget_move(widget_button_base(screen->widgets.ok_b),
			y, screen->field_x);
	widget_move(widget_button_base(screen->widgets.help_b),
			y, screen->field_x + 10);
	widget_move(widget_button_base(screen->widgets.cancel_b),
			y, screen->field_x + 20);
}

static void config_screen_network_change(void *arg, int value)
{
	struct config_screen *screen = arg;
	screen->net_conf_type = value;
	widgetset_unpost(screen->widgetset);
	config_screen_layout_widgets(screen);
	widgetset_post(screen->widgetset);
}

static void config_screen_autoboot_change(void *arg, int value)
{
	struct config_screen *screen = arg;
	screen->autoboot_type = value;
	widgetset_unpost(screen->widgetset);
	config_screen_layout_widgets(screen);
	widgetset_post(screen->widgetset);
}

static struct interface_config *first_active_interface(
		const struct config *config)
{
	unsigned int i;

	for (i = 0; i < config->network.n_interfaces; i++) {
		if (config->network.interfaces[i]->ignore)
			continue;
		return config->network.interfaces[i];
	}
	return NULL;
}

static enum net_conf_type find_net_conf_type(const struct config *config)
{
	struct interface_config *ifcfg;

	ifcfg = first_active_interface(config);

	if (!ifcfg)
		return NET_CONF_TYPE_DHCP_ALL;

	else if (ifcfg->method == CONFIG_METHOD_DHCP)
		return NET_CONF_TYPE_DHCP_ONE;

	else if (ifcfg->method == CONFIG_METHOD_STATIC)
		return NET_CONF_TYPE_STATIC;

	assert(0);
	return NET_CONF_TYPE_DHCP_ALL;
}

static void config_screen_setup_empty(struct config_screen *screen)
{
	widget_new_label(screen->widgetset, 2, screen->field_x,
			_("Waiting for configuration data..."));
	screen->widgets.cancel_b = widget_new_button(screen->widgetset,
			4, screen->field_x, 6, _("Cancel"),
			cancel_click, screen);
}


static void config_screen_setup_widgets(struct config_screen *screen,
		const struct config *config,
		const struct system_info *sysinfo)
{
	struct nc_widgetset *set = screen->widgetset;
	struct interface_config *ifcfg;
	char *str, *ip, *mask, *gw;
	enum net_conf_type type;
	unsigned int i;
	bool found;

	build_assert(sizeof(screen->widgets) / sizeof(struct widget *)
			== N_FIELDS);

	type = screen->net_conf_type;
	ifcfg = first_active_interface(config);

	screen->widgets.autoboot_l = widget_new_label(set, 0, 0,
					_("Autoboot:"));
	screen->widgets.autoboot_f = widget_new_select(set, 0, 0, 55);

	widget_select_on_change(screen->widgets.autoboot_f,
			config_screen_autoboot_change, screen);

	screen->widgets.boot_device_f = widget_new_select(set, 0, 0, 55);

	widget_select_add_option(screen->widgets.autoboot_f,
					AUTOBOOT_DISABLED,
					_("Don't autoboot"),
					screen->autoboot_type ==
						AUTOBOOT_DISABLED);
	widget_select_add_option(screen->widgets.autoboot_f,
					AUTOBOOT_ANY,
					_("Autoboot from any "
						"disk/network device"),
					screen->autoboot_type ==
						AUTOBOOT_ANY);
	widget_select_add_option(screen->widgets.autoboot_f,
					AUTOBOOT_ONE,
					_("Only autoboot from a specific "
						"disk/network device"),
					screen->autoboot_type ==
						AUTOBOOT_ONE);

	found = false;

	for (i = 0; i < sysinfo->n_blockdevs; i++) {
		struct blockdev_info *bd = sysinfo->blockdevs[i];
		bool selected;
		char *label;

		selected = config->boot_device &&
				!strcmp(config->boot_device, bd->uuid);
		if (selected)
			found = true;

		label = talloc_asprintf(screen, _("disk: %s [uuid: %s]"),
				bd->name, bd->uuid);

		widget_select_add_option(screen->widgets.boot_device_f, i,
					label, selected);
	}

	for (i = 0; i < sysinfo->n_interfaces; i++) {
		struct interface_info *info = sysinfo->interfaces[i];
		char *label, mac[20];
		bool selected;

		mac_str(info->hwaddr, info->hwaddr_size, mac, sizeof(mac));
		selected = config->boot_device &&
				!strcmp(config->boot_device, mac);
		if (selected)
			found = true;

		label = talloc_asprintf(screen, _("net:  %s [mac: %s]"),
				info->name, mac);

		widget_select_add_option(screen->widgets.boot_device_f,
						i + sysinfo->n_blockdevs,
						label, selected);
	}

	if (screen->autoboot_type == AUTOBOOT_ONE && !found) {
		char *label;

		label = talloc_asprintf(screen, _("Unknown UUID: %s"),
				config->boot_device);

		widget_select_add_option(screen->widgets.boot_device_f, -1,
						label, true);
	}

	str = talloc_asprintf(screen, "%d", config->autoboot_timeout_sec);
	screen->widgets.timeout_l = widget_new_label(set, 0, 0, _("Timeout:"));
	screen->widgets.timeout_f = widget_new_textbox(set, 0, 0, 5, str);
	screen->widgets.timeout_help_l = widget_new_label(set, 0, 0,
					_("seconds"));

	widget_textbox_set_fixed_size(screen->widgets.timeout_f);
	widget_textbox_set_validator_integer(screen->widgets.timeout_f, 0, 999);

	screen->widgets.network_l = widget_new_label(set, 0, 0, _("Network:"));
	screen->widgets.network_f = widget_new_select(set, 0, 0, 50);

	widget_select_add_option(screen->widgets.network_f,
					NET_CONF_TYPE_DHCP_ALL,
					_("DHCP on all active interfaces"),
					type == NET_CONF_TYPE_DHCP_ALL);
	widget_select_add_option(screen->widgets.network_f,
					NET_CONF_TYPE_DHCP_ONE,
					_("DHCP on a specific interface"),
					type == NET_CONF_TYPE_DHCP_ONE);
	widget_select_add_option(screen->widgets.network_f,
					NET_CONF_TYPE_STATIC,
					_("Static IP configuration"),
					type == NET_CONF_TYPE_STATIC);

	widget_select_on_change(screen->widgets.network_f,
			config_screen_network_change, screen);

	screen->widgets.iface_l = widget_new_label(set, 0, 0, _("Device:"));
	screen->widgets.iface_f = widget_new_select(set, 0, 0, 50);

	for (i = 0; i < sysinfo->n_interfaces; i++) {
		struct interface_info *info = sysinfo->interfaces[i];
		char str[50], mac[20];
		bool is_default;

		is_default = ifcfg && !memcmp(ifcfg->hwaddr, info->hwaddr,
					sizeof(ifcfg->hwaddr));

		mac_str(info->hwaddr, info->hwaddr_size, mac, sizeof(mac));
		snprintf(str, sizeof(str), "%s [%s, %s]", info->name, mac,
				info->link ? _("link up") : _("link down"));

		widget_select_add_option(screen->widgets.iface_f,
						i, str, is_default);
	}

	gw = ip = mask = NULL;
	if (ifcfg && ifcfg->method == CONFIG_METHOD_STATIC) {
		char *sep;

		str = talloc_strdup(screen, ifcfg->static_config.address);
		sep = strchr(str, '/');
		ip = str;

		if (sep) {
			*sep = '\0';
			mask = sep + 1;
		}
		gw = ifcfg->static_config.gateway;
	}

	screen->widgets.ip_addr_l = widget_new_label(set, 0, 0, _("IP/mask:"));
	screen->widgets.ip_addr_f = widget_new_textbox(set, 0, 0, 16, ip);
	screen->widgets.ip_mask_l = widget_new_label(set, 0, 0, "/");
	screen->widgets.ip_mask_f = widget_new_textbox(set, 0, 0, 3, mask);
	screen->widgets.ip_addr_mask_help_l =
		widget_new_label(set, 0, 0, _("(eg. 192.168.0.10 / 24)"));

	widget_textbox_set_fixed_size(screen->widgets.ip_addr_f);
	widget_textbox_set_fixed_size(screen->widgets.ip_mask_f);
	widget_textbox_set_validator_ipv4(screen->widgets.ip_addr_f);
	widget_textbox_set_validator_integer(screen->widgets.ip_mask_f, 1, 31);

	screen->widgets.gateway_l = widget_new_label(set, 0, 0, _("Gateway:"));
	screen->widgets.gateway_f = widget_new_textbox(set, 0, 0, 16, gw);
	screen->widgets.gateway_help_l =
		widget_new_label(set, 0, 0, _("(eg. 192.168.0.1)"));

	widget_textbox_set_fixed_size(screen->widgets.gateway_f);
	widget_textbox_set_validator_ipv4(screen->widgets.gateway_f);

	str = talloc_strdup(screen, "");
	for (i = 0; i < config->network.n_dns_servers; i++) {
		str = talloc_asprintf_append(str, "%s%s",
				(i == 0) ? "" : " ",
				config->network.dns_servers[i]);
	}

	screen->widgets.dns_l = widget_new_label(set, 0, 0,
					_("DNS Server(s):"));
	screen->widgets.dns_f = widget_new_textbox(set, 0, 0, 32, str);
	screen->widgets.dns_help_l =
		widget_new_label(set, 0, 0, _("(eg. 192.168.0.2)"));

	widget_textbox_set_validator_ipv4_multi(screen->widgets.dns_f);

	screen->widgets.dns_dhcp_help_l = widget_new_label(set, 0, 0,
			_("(if not provided by DHCP server)"));

	screen->widgets.ok_b = widget_new_button(set, 0, 0, 6, _("OK"),
			ok_click, screen);
	screen->widgets.help_b = widget_new_button(set, 0, 0, 6, _("Help"),
			help_click, screen);
	screen->widgets.cancel_b = widget_new_button(set, 0, 0, 6, _("Cancel"),
			cancel_click, screen);
}

static void config_screen_widget_focus(struct nc_widget *widget, void *arg)
{
	struct config_screen *screen = arg;
	int w_y, s_max;

	w_y = widget_y(widget) + widget_focus_y(widget);
	s_max = getmaxy(screen->scr.sub_ncw) - 1;

	if (w_y < screen->scroll_y)
		screen->scroll_y = w_y;

	else if (w_y + screen->scroll_y + 1 > s_max)
		screen->scroll_y = 1 + w_y - s_max;

	else
		return;

	pad_refresh(screen);
}

static void config_screen_draw(struct config_screen *screen,
		const struct config *config,
		const struct system_info *sysinfo)
{
	bool repost = false;
	int height;

	/* The size of the pad we'll need depends on the number of interfaces.
	 *
	 * We use N_FIELDS (which is quite conservative, as some fields share
	 * a line) as a base, then add 3 (as the network select field is
	 * takes 3 lines), and n_interfaces (as the network interface field
	 * has n_interfaces lines).
	 */
	height = N_FIELDS + 3;
	if (sysinfo)
		height += sysinfo->n_interfaces;
	if (!screen->pad || getmaxy(screen->pad) < height) {
		if (screen->pad)
			delwin(screen->pad);
		screen->pad = newpad(height, COLS);
	}

	if (screen->widgetset) {
		widgetset_unpost(screen->widgetset);
		talloc_free(screen->widgetset);
		repost = true;
	}

	screen->widgetset = widgetset_create(screen, screen->scr.main_ncw,
			screen->pad);
	widgetset_set_widget_focus(screen->widgetset,
			config_screen_widget_focus, screen);

	if (!config || !sysinfo) {
		config_screen_setup_empty(screen);
	} else {
		screen->net_conf_type = find_net_conf_type(config);
		if (!config->autoboot_enabled)
			screen->autoboot_type = AUTOBOOT_DISABLED;
		else
			screen->autoboot_type = config->boot_device ?
					AUTOBOOT_ONE : AUTOBOOT_ANY;

		config_screen_setup_widgets(screen, config, sysinfo);
		config_screen_layout_widgets(screen);
	}

	if (repost)
		widgetset_post(screen->widgetset);
}

void config_screen_update(struct config_screen *screen,
		const struct config *config,
		const struct system_info *sysinfo)
{
	config_screen_draw(screen, config, sysinfo);
	pad_refresh(screen);
}

static int config_screen_destroy(void *arg)
{
	struct config_screen *screen = arg;
	if (screen->pad)
		delwin(screen->pad);
	return 0;
}

struct config_screen *config_screen_init(struct cui *cui,
		const struct config *config,
		const struct system_info *sysinfo,
		void (*on_exit)(struct cui *))
{
	struct config_screen *screen;

	screen = talloc_zero(cui, struct config_screen);
	talloc_set_destructor(screen, config_screen_destroy);
	nc_scr_init(&screen->scr, pb_config_screen_sig, 0,
			cui, config_screen_process_key,
			config_screen_post, config_screen_unpost,
			config_screen_resize);

	screen->cui = cui;
	screen->on_exit = on_exit;
	screen->label_x = 2;
	screen->field_x = 17;

	screen->scr.frame.ltitle = talloc_strdup(screen,
			_("Petitboot System Configuration"));
	screen->scr.frame.rtitle = NULL;
	screen->scr.frame.help = talloc_strdup(screen,
			_("tab=next, shift+tab=previous, x=exit, h=help"));
	nc_scr_frame_draw(&screen->scr);

	scrollok(screen->scr.sub_ncw, true);

	config_screen_draw(screen, config, sysinfo);

	return screen;
}