/*
 * netifd - network interface daemon
 * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation
 *
 * 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.
 */
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#include "netifd.h"
#include "device.h"
#include "interface.h"

static struct avl_tree aliases;

struct alias_device {
	struct avl_node avl;
	struct device dev;
	struct device_user dep;
	struct device_user new_dep;
	bool update;
	char name[];
};

static const struct device_type alias_device_type;

static void alias_set_device(struct alias_device *alias, struct device *dev)
{
	if (dev == alias->dep.dev) {
		if (alias->update) {
			device_remove_user(&alias->new_dep);
			alias->update = false;
			if (dev)
				device_set_present(&alias->dev, true);
		}
		return;
	}

	device_set_present(&alias->dev, false);
	device_remove_user(&alias->new_dep);
	if (alias->dev.active) {
		if (dev)
			device_add_user(&alias->new_dep, dev);

		alias->update = true;
		return;
	}

	alias->update = false;
	device_remove_user(&alias->dep);
	alias->dev.hidden = !dev;
	if (dev) {
		device_set_ifindex(&alias->dev, dev->ifindex);
		device_set_ifname(&alias->dev, dev->ifname);
		device_add_user(&alias->dep, dev);
	} else
		device_set_ifname(&alias->dev, "");
}

static int
alias_device_set_state(struct device *dev, bool state)
{
	struct alias_device *alias;

	alias = container_of(dev, struct alias_device, dev);
	if (!alias->dep.dev)
		return -1;

	if (state)
		return device_claim(&alias->dep);

	device_release(&alias->dep);
	if (alias->update)
		alias_set_device(alias, alias->new_dep.dev);

	return 0;
}

static void alias_device_cb(struct device_user *dep, enum device_event ev)
{
	struct alias_device *alias;
	bool new_state = false;

	alias = container_of(dep, struct alias_device, dep);
	switch (ev) {
	case DEV_EVENT_ADD:
		new_state = true;
	case DEV_EVENT_REMOVE:
		device_set_present(&alias->dev, new_state);
		break;
	case DEV_EVENT_LINK_UP:
		new_state = true;
	case DEV_EVENT_LINK_DOWN:
		device_set_link(&alias->dev, new_state);
		break;
	case DEV_EVENT_UPDATE_IFINDEX:
		device_set_ifindex(&alias->dev, dep->dev->ifindex);
		break;
	default:
		device_broadcast_event(&alias->dev, ev);
		break;
	}
}

static struct device *
alias_device_create(const char *name, struct blob_attr *attr)
{
	struct alias_device *alias;

	alias = calloc(1, sizeof(*alias) + strlen(name) + 1);
	if (!alias)
		return NULL;

	strcpy(alias->name, name);
	alias->dev.set_state = alias_device_set_state;
	alias->dev.hidden = true;
	device_init_virtual(&alias->dev, &alias_device_type, NULL);
	alias->avl.key = alias->name;
	avl_insert(&aliases, &alias->avl);
	alias->dep.alias = true;
	alias->dep.cb = alias_device_cb;
	device_check_state(&alias->dev);

	return &alias->dev;
}

static void alias_device_free(struct device *dev)
{
	struct alias_device *alias;

	alias = container_of(dev, struct alias_device, dev);
	device_remove_user(&alias->new_dep);
	device_remove_user(&alias->dep);
	avl_delete(&aliases, &alias->avl);
	free(alias);
}

static int alias_check_state(struct device *dev)
{
	struct alias_device *alias;
	struct interface *iface;
	struct device *ndev = NULL;

	alias = container_of(dev, struct alias_device, dev);

	iface = vlist_find(&interfaces, alias->name, iface, node);
	if (iface && iface->state == IFS_UP)
		ndev = iface->l3_dev.dev;

	alias_set_device(alias, ndev);

	return 0;
}

static const struct device_type alias_device_type = {
	.name = "Network alias",
	.create = alias_device_create,
	.free = alias_device_free,
	.check_state = alias_check_state,
};

void
alias_notify_device(const char *name, struct device *dev)
{
	struct alias_device *alias;

	device_lock();

	alias = avl_find_element(&aliases, name, alias, avl);
	if (alias)
		alias_set_device(alias, dev);

	device_unlock();
}

struct device *
device_alias_get(const char *name)
{
	struct alias_device *alias;

	alias = avl_find_element(&aliases, name, alias, avl);
	if (alias)
		return &alias->dev;

	return alias_device_create(name, NULL);
}

static void __init alias_init(void)
{
	avl_init(&aliases, avl_strcmp, false, NULL);
}