#include <netlink/netlink.h>
#include <netlink/genl/genl.h>
#include <netlink/genl/ctrl.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define GENL_FAMILY_NAME		"bluetooth"
#define GENL_VERSION			0x01

static int family;

#define DOWN	0
#define UP	1

enum {
	ATTR_UNSPEC,
	INDEX,
	CHANGED,
	EVENT,
	GRPID,
	/* Add attributes here */
	__ATTR_MAX,
	ATTR_MAX  =  __ATTR_MAX - 1
};

static struct nla_policy policy[ATTR_MAX + 1] = {
	[INDEX]		= { .type = NLA_U16 },
	[CHANGED]	= { .type = NLA_U32 },
	[EVENT]		= { .type = NLA_U16 },
	[GRPID]		= { .type = NLA_U32 },
};

enum {
	CMD_UNSPEC,
	NEWHOST,
	DELHOST,
	HOST,
	GETGRPID,
	/* Add command here */
	__CMD_MAX,
	CMD_MAX  = __CMD_MAX - 1
};


static int parse_cb(struct nl_msg *msg, void *arg)
{
	int err, ret;
	int *id = arg;
	int index, changed;
	struct nlmsghdr *nlh = nlmsg_hdr(msg);
	struct nlattr *attrs[ATTR_MAX+1];

	struct genlmsghdr *ghdr = nlmsg_data(nlh);

	err = genlmsg_parse(nlh, 0, attrs, ATTR_MAX, NULL);
	if (err < 0)
		return -EINVAL;

	switch (ghdr->cmd) {
	case HOST:
		index = nla_get_u16(attrs[INDEX]);
		changed = nla_get_u32(attrs[CHANGED]);
		printf("\nHCI%d : changed0x%x\n", index, changed);
		ret = 0;
		break;
	case NEWHOST:
		index = nla_get_u16(attrs[INDEX]);
		changed = nla_get_u32(attrs[CHANGED]);
		printf("\nNew Device HCI%d : changed0x%x\n", index, changed);
		ret = 0;
		break;
	case DELHOST:
		index = nla_get_u16(attrs[INDEX]);
		changed = nla_get_u32(attrs[CHANGED]);
		printf("\nRemoved Device HCI%d : changed0x%x\n", index, changed);
		ret = 0;
		break;
	case GETGRPID:
		if(!attrs[GRPID]) {
			printf("\nNo Group ID\n");
			ret = -EINVAL;
		} else
			*id =  nla_get_u32(attrs[GRPID]);
			ret = 0;
		break;

	default:
		printf("\nUnknown command");
		ret = -EINVAL;
		break;
	}

	return ret;
}

static int ack_handler(struct nl_msg *msg, void *arg)
{
	int *ret = arg;
	*ret = 0;
	return NL_STOP;
}

int get_group_id(struct nl_handle *sock)
{
	int ret = 1, grpid;
	struct nl_msg *msg;
	struct nl_cb *cb;
	
	msg = nlmsg_alloc();
	cb = nl_cb_alloc(NL_CB_DEFAULT);
	
	genlmsg_put(msg, NL_AUTO_PID, NL_AUTO_SEQ, family, 0,
			NLM_F_REQUEST, GETGRPID, GENL_VERSION);

	nl_send_auto_complete(sock, msg);

	nl_cb_set(cb, NL_CB_ACK, NL_CB_CUSTOM, ack_handler, &ret);
	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, parse_cb, &grpid);
	
	while (ret > 0)
		nl_recvmsgs(sock, cb);

	nl_cb_put(cb);
	nlmsg_free(msg);

	return grpid;
}

int main()
{
	struct nl_handle *sock;
	struct nl_msg *msg;
	int err;
	int grp_id;

	sock = nl_handle_alloc();

	genl_connect(sock);

	family = genl_ctrl_resolve(sock, GENL_FAMILY_NAME);
	if (family < 0)
		return -1;

	grp_id = get_group_id(sock);
	if (grp_id < 0)
		return -1;

	err = nl_socket_add_membership(sock, grp_id);
	if (err < 0)
		return -1;

	nl_socket_modify_cb(sock, NL_CB_SEQ_CHECK, NL_CB_CUSTOM, parse_cb, NULL);
	while(1)
	err = nl_recvmsgs_default(sock);

	return 0;
}