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

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

enum {
	BRIDGE_ATTR_IFNAME,
	BRIDGE_ATTR_STP,
	__BRIDGE_ATTR_MAX
};

static const struct blobmsg_policy bridge_attrs[__BRIDGE_ATTR_MAX] = {
	[BRIDGE_ATTR_IFNAME] = { "ifname", BLOBMSG_TYPE_ARRAY },
	[BRIDGE_ATTR_STP] = { "stp", BLOBMSG_TYPE_BOOL },
};

static const union config_param_info bridge_attr_info[__BRIDGE_ATTR_MAX] = {
	[BRIDGE_ATTR_IFNAME] = { .type = BLOBMSG_TYPE_STRING },
};

static const struct config_param_list bridge_attr_list = {
	.n_params = __BRIDGE_ATTR_MAX,
	.params = bridge_attrs,
	.info = bridge_attr_info,

	.n_next = 1,
	.next = { &device_attr_list },
};

static struct device *bridge_create(struct blob_attr *attr);
static void bridge_free(struct device *dev);
static void bridge_dump_status(struct device *dev, struct blob_buf *b);

const struct device_type bridge_device_type = {
	.name = "Bridge",
	.config_params = &bridge_attr_list,

	.create = bridge_create,
	.free = bridge_free,
	.dump_status = bridge_dump_status,
};

struct bridge_state {
	struct device dev;
	device_state_cb set_state;

	bool active;

	struct list_head members;
	int n_present;
};

struct bridge_member {
	struct list_head list;
	struct bridge_state *bst;
	struct device_user dev;
	bool present;
};

static int
bridge_disable_member(struct bridge_member *bm)
{
	struct bridge_state *bst = bm->bst;

	if (!bm->present)
		return 0;

	system_bridge_delif(&bst->dev, bm->dev.dev);
	device_release(bm->dev.dev);

	return 0;
}

static int
bridge_enable_member(struct bridge_member *bm)
{
	struct bridge_state *bst = bm->bst;
	int ret;

	if (!bm->present)
		return 0;

	ret = device_claim(bm->dev.dev);
	if (ret < 0)
		goto error;

	ret = system_bridge_addif(&bst->dev, bm->dev.dev);
	if (ret < 0)
		goto error;

	return 0;

error:
	bm->present = false;
	bst->n_present--;
	return ret;
}

static void
bridge_member_cb(struct device_user *dev, enum device_event ev)
{
	struct bridge_member *bm = container_of(dev, struct bridge_member, dev);
	struct bridge_state *bst = bm->bst;

	switch (ev) {
	case DEV_EVENT_ADD:
		assert(!bm->present);

		bm->present = true;
		bst->n_present++;

		if (bst->dev.active)
			bridge_enable_member(bm);
		else if (bst->n_present == 1)
			device_set_present(&bst->dev, true);

		break;
	case DEV_EVENT_REMOVE:
		if (!bm->present)
			return;

		if (bst->dev.active)
			bridge_disable_member(bm);

		bm->present = false;
		bm->bst->n_present--;
		if (bst->n_present == 0)
			device_set_present(&bst->dev, false);

		break;
	default:
		return;
	}
}

static int
bridge_set_down(struct bridge_state *bst)
{
	struct bridge_member *bm;

	bst->set_state(&bst->dev, false);

	list_for_each_entry(bm, &bst->members, list)
		bridge_disable_member(bm);

	system_bridge_delbr(&bst->dev);

	return 0;
}

static int
bridge_set_up(struct bridge_state *bst)
{
	struct bridge_member *bm;
	int ret;

	if (!bst->n_present)
		return -ENOENT;

	ret = system_bridge_addbr(&bst->dev);
	if (ret < 0)
		goto out;

	list_for_each_entry(bm, &bst->members, list)
		bridge_enable_member(bm);

	if (!bst->n_present) {
		/* initialization of all member interfaces failed */
		system_bridge_delbr(&bst->dev);
		device_set_present(&bst->dev, false);
		return -ENOENT;
	}

	ret = bst->set_state(&bst->dev, true);
	if (ret < 0)
		bridge_set_down(bst);

out:
	return ret;
}

static int
bridge_set_state(struct device *dev, bool up)
{
	struct bridge_state *bst;

	bst = container_of(dev, struct bridge_state, dev);

	if (up)
		return bridge_set_up(bst);
	else
		return bridge_set_down(bst);
}

static struct bridge_member *
bridge_create_member(struct bridge_state *bst, struct device *dev)
{
	struct bridge_member *bm;

	bm = calloc(1, sizeof(*bm));
	bm->bst = bst;
	bm->dev.cb = bridge_member_cb;
	device_add_user(&bm->dev, dev);

	list_add_tail(&bm->list, &bst->members);

	if (bst->dev.active)
		bridge_enable_member(bm);

	return bm;
}

static void
bridge_free_member(struct bridge_member *bm)
{
	if (bm->present) {
		bridge_member_cb(&bm->dev, DEV_EVENT_REMOVE);
		bm->bst->n_present--;
		if (bm->bst->dev.active)
			bridge_disable_member(bm);
	}

	list_del(&bm->list);
	device_remove_user(&bm->dev);
	free(bm);
}

static void
bridge_add_member(struct bridge_state *bst, const char *name)
{
	struct device *dev;

	dev = device_get(name, true);
	if (!dev)
		return;

	bridge_create_member(bst, dev);
}

static int
bridge_hotplug_add(struct device *dev, struct device *member)
{
	struct bridge_state *bst = container_of(dev, struct bridge_state, dev);

	bridge_create_member(bst, member);

	return 0;
}

static int
bridge_hotplug_del(struct device *dev, struct device *member)
{
	struct bridge_state *bst = container_of(dev, struct bridge_state, dev);
	struct bridge_member *bm;

	list_for_each_entry(bm, &bst->members, list) {
		if (bm->dev.dev != member)
			continue;

		bridge_free_member(bm);
		return 0;
	}

	return -ENOENT;
}

static const struct device_hotplug_ops bridge_ops = {
	.add = bridge_hotplug_add,
	.del = bridge_hotplug_del
};

static void
bridge_free(struct device *dev)
{
	struct bridge_state *bst;
	struct bridge_member *bm;

	bst = container_of(dev, struct bridge_state, dev);
	while (!list_empty(&bst->members)) {
		bm = list_first_entry(&bst->members, struct bridge_member, list);
		bridge_free_member(bm);
	}
	free(bst);
}

static void
bridge_dump_status(struct device *dev, struct blob_buf *b)
{
	struct bridge_state *bst;
	struct bridge_member *bm;
	void *list;

	bst = container_of(dev, struct bridge_state, dev);

	list = blobmsg_open_array(b, "bridge-members");
	list_for_each_entry(bm, &bst->members, list) {
		blobmsg_add_string(b, NULL, bm->dev.dev->ifname);
	}
	blobmsg_close_array(b, list);
}

static struct device *
bridge_create(struct blob_attr *attr)
{
	struct blob_attr *tb_dev[__DEV_ATTR_MAX];
	struct blob_attr *tb_br[__BRIDGE_ATTR_MAX];
	struct blob_attr *cur;
	struct bridge_state *bst;
	struct device *dev = NULL;
	const char *name;
	int rem;

	blobmsg_parse(device_attr_list.params, __DEV_ATTR_MAX, tb_dev,
		blob_data(attr), blob_len(attr));
	blobmsg_parse(bridge_attrs, __BRIDGE_ATTR_MAX, tb_br,
		blob_data(attr), blob_len(attr));

	if (!tb_dev[DEV_ATTR_NAME])
		return NULL;

	if (!tb_br[BRIDGE_ATTR_IFNAME])
		return NULL;

	name = blobmsg_data(tb_dev[DEV_ATTR_NAME]);

	bst = calloc(1, sizeof(*bst));
	if (!bst)
		return NULL;

	dev = &bst->dev;
	device_init(dev, &bridge_device_type, name);
	device_init_settings(dev, tb_dev);

	bst->set_state = dev->set_state;
	dev->set_state = bridge_set_state;

	dev->hotplug_ops = &bridge_ops;

	INIT_LIST_HEAD(&bst->members);

	blobmsg_for_each_attr(cur, tb_br[BRIDGE_ATTR_IFNAME], rem) {
		bridge_add_member(bst, blobmsg_data(cur));
	}

	return dev;
}