#include "device-common.h"
#include "netlink.h"
#include "util.h"

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

#include <arpa/inet.h>

#include <linux/if.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>

static unsigned long strtoul_safe(const char *str) {
	char *endptr;

	errno = 0;
	unsigned long val = strtoul(str, &endptr, 10);
	if (endptr == str || *endptr)
		errno = EINVAL;

	return val;
}

static bool parse_address(ipaddr_t *addr, const char *str) {
	if (inet_pton(AF_INET, str, &addr->addr4)) {
		addr->af = AF_INET;
		return true;
	}

	if (inet_pton(AF_INET6, str, &addr->addr6)) {
		addr->af = AF_INET6;
		return true;
	}

	return false;
}

static bool parse_prefix(ipaddr_prefix_t *prefix, const char *str, bool allow_host) {
	const char *slash = strrchr(str, '/');
	if (!slash)
		return false;

	size_t len = slash - str;
	char buf[len+1];
	memcpy(buf, str, len);
	buf[len] = 0;

	if (!parse_address(&prefix->addr, buf))
		return false;

	long plen = strtoul_safe(slash + 1);
	if (errno)
		return false;

	switch (prefix->addr.af) {
	case AF_INET:
		if (plen > 32)
			return false;
		break;

	case AF_INET6:
		if (plen > 128)
			return false;
		break;

	default:
		assert(false);
		__builtin_unreachable();
	}

	prefix->plen = plen;

	// TODO: Implement allow_host

	return true;
}

static bool process_section_device(device_common_t *device, struct json_object *section) {
	return true;
}

static bool process_section_static(device_common_t *device, struct json_object *section) {
	struct json_object *addresses = neco_json_get_value(section, "addresses", json_type_array);
	if (addresses) {
		for (size_t i = 0; i < json_object_array_length(addresses); i++) {
			struct json_object *address = json_object_array_get_idx(addresses, i);
			if (!json_object_is_type(address, json_type_string)) {
				fprintf(stderr, "interface: static: invalid address entry of type %s\n", json_type_to_name(json_object_get_type(address)));
				continue;
			}

			ipaddr_prefix_t p;
			if (!parse_prefix(&p, json_object_get_string(address), true)) {
				fprintf(stderr, "interface: static: unable to parse Address %s\n", json_object_get_string(address));
				break;
			}

			if (!VECTOR_ADD(device->addrs, p)) {
				fprintf(stderr, "interface: static: adding address failed\n");
				return false;
			}
		}
	}

	return true;
}

static bool process_section_bridge(device_common_t *device, struct json_object *section) {
	const char *master = neco_json_get_string(section, "master");
	if (master)
		strncpy(device->master, master, sizeof(device->master)-1);

	return true;
}

bool device_common_process_config(device_common_t *device, struct json_object *config) {
	struct json_object *sec_device = neco_json_get_value(config, "device", json_type_object);
	if (sec_device) {
		if (!process_section_device(device, sec_device))
			return false;
	}

	struct json_object *sec_static = neco_json_get_value(config, "static", json_type_object);
	if (sec_static) {
		if (!process_section_static(device, sec_static))
			return false;
	}

	struct json_object *sec_bridge = neco_json_get_value(config, "bridge", json_type_object);
	if (sec_bridge) {
		if (!process_section_bridge(device, sec_bridge))
			return false;
	}

	return true;
}

static bool device_common_set_link_flags(unsigned ifindex, unsigned change, unsigned flags) {
	char buf[MNL_SOCKET_BUFFER_SIZE];

	struct mnl_socket *nl = nl_socket();

	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
	nlh->nlmsg_type	= RTM_SETLINK;
	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	int seq = nlh->nlmsg_seq = nl_seq();

	struct ifinfomsg *ifi = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifi));
	ifi->ifi_index = ifindex;
	ifi->ifi_family = AF_UNSPEC;

	ifi->ifi_change = change;
	ifi->ifi_flags = flags;

	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
		perror("mnl_socket_sendto");
		return false;
	}

	int ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	if (ret == -1) {
		perror("mnl_socket_recvfrom");
		return false;
	}

	ret = mnl_cb_run(buf, ret, seq, mnl_socket_get_portid(nl), NULL, NULL);
	if (ret == -1) {
		perror("mnl_cb_run");
		return false;
	}

	return true;
}

static bool device_common_set_link_state(unsigned ifindex, bool up) {
	return device_common_set_link_flags(ifindex, IFF_UP, up ? IFF_UP : 0);
}

static bool device_common_set_ipaddr(unsigned ifindex, ipaddr_prefix_t *addr, bool add) {
	char buf[MNL_SOCKET_BUFFER_SIZE];

	struct mnl_socket *nl = nl_socket();

	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
	nlh->nlmsg_type	= add ? RTM_NEWADDR : RTM_DELADDR;
	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	if (add)
		nlh->nlmsg_flags |= NLM_F_CREATE | NLM_F_REPLACE;

	int seq = nlh->nlmsg_seq = nl_seq();

	struct ifaddrmsg *ifa = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifa));
	ifa->ifa_index = ifindex;
	ifa->ifa_family = addr->addr.af;

	ifa->ifa_prefixlen = addr->plen;

	switch (addr->addr.af) {
	case AF_INET:
		mnl_attr_put(nlh, IFA_LOCAL, 4, &addr->addr.addr4);
		break;

	case AF_INET6:
		mnl_attr_put(nlh, IFA_LOCAL, 16, &addr->addr.addr6);
		break;

	default:
		errno = EINVAL;
		return false;
	}

	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
		perror("mnl_socket_sendto");
		return false;
	}

	int ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	if (ret == -1) {
		perror("mnl_socket_recvfrom");
		return false;
	}

	ret = mnl_cb_run(buf, ret, seq, mnl_socket_get_portid(nl), NULL, NULL);
	if (ret == -1) {
		perror("mnl_cb_run");
		return false;
	}

	return true;
}

static bool device_common_set_master(unsigned ifindex, unsigned master) {
	char buf[MNL_SOCKET_BUFFER_SIZE];

	struct mnl_socket *nl = nl_socket();

	struct nlmsghdr *nlh = mnl_nlmsg_put_header(buf);
	nlh->nlmsg_type	= RTM_SETLINK;
	nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	int seq = nlh->nlmsg_seq = nl_seq();

	struct ifinfomsg *ifi = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifi));
	ifi->ifi_index = ifindex;
	ifi->ifi_family = AF_UNSPEC;

	mnl_attr_put_u32(nlh, IFLA_MASTER, master);

	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
		perror("mnl_socket_sendto");
		return false;
	}

	int ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
	if (ret == -1) {
		perror("mnl_socket_recvfrom");
		return false;
	}

	ret = mnl_cb_run(buf, ret, seq, mnl_socket_get_portid(nl), NULL, NULL);
	if (ret == -1) {
		perror("mnl_cb_run");
		return false;
	}

	return true;
}

void device_common_init(device_common_t *device, int ifindex) {
	if (*device->master) {
		unsigned master = if_nametoindex(device->master);
		if (!master)
			return;

		device_common_set_master(ifindex, master);
	}

	device_common_set_link_state(ifindex, true);

	if (!*device->master) {
		for (size_t i = 0; i < VECTOR_LEN(device->addrs); i++)
			device_common_set_ipaddr(ifindex, &VECTOR_INDEX(device->addrs, i), true);
	}
}

void device_common_release(device_common_t *device, int ifindex) {
	if (!*device->master) {
		for (size_t i = 0; i < VECTOR_LEN(device->addrs); i++)
			device_common_set_ipaddr(ifindex, &VECTOR_INDEX(device->addrs, i), false);
	}

	device_common_set_link_state(ifindex, false);

	if (*device->master)
		device_common_set_master(ifindex, 0);
}