#include "device.h"
#include "netlink.h"
#include "util.h"
#include "vector.h"

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

#include <arpa/inet.h>
#include <net/if.h>
#include <netinet/ether.h>
#include <netinet/in.h>

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

static device_type_t device_type_interface;

typedef struct _ipaddr {
	int af;
	union {
		struct in_addr addr4;
		struct in6_addr addr6;
	};
} ipaddr_t;

typedef struct _ipprefix {
	ipaddr_t addr;
	uint8_t plen;
} ipaddr_prefix_t;

typedef VECTOR(ipaddr_prefix_t) ipaddr_prefix_vector_t;

typedef struct _device_interface {
	device_t device;

	struct ether_addr macaddr;
	uint16_t mtu;

	ipaddr_prefix_vector_t addrs;
} device_interface_t;

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 void interface_free(device_t *dev) {
	device_interface_t *iface = container_of(dev, device_interface_t, device);

	VECTOR_FREE(iface->addrs);
	free(NODE_NAME(dev));
	free(iface);
}

static bool process_section_device(device_interface_t *iface, struct json_object *section) {
	return true;
}

static bool process_section_static(device_interface_t *iface, 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(iface->addrs, p)) {
				fprintf(stderr, "interface: static: adding address failed\n");
				return false;
			}
		}
	}


	/*
	list_for_each_entry(field, &section->fields, node) {
		switch (lookup_keyword(field->key)) {
		case KW_Address: {
			ipaddr_prefix_t p;
			if (!parse_prefix(&p, field->value, true)) {
				fprintf(stderr, "interface: [Static]: unable to parse Address %s\n", field->value);
				break;
			}

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

			break;
		}

		default:
			fprintf(stderr, "interface: [Static]: unknown field %s\n", field->key);
		}
	}
	*/

	return true;
}

static device_t * interface_process_config(const char *name, struct json_object *config) {
	device_interface_t *iface = calloc(1, sizeof(*iface));
	if (!iface)
		return NULL;

	device_t *dev = &iface->device;
	dev->type = &device_type_interface;

	NODE_NAME(dev) = strdup(name);
	if (!NODE_NAME(dev)) {
		free(iface);
		return NULL;
	}

	struct json_object *sec_device = neco_json_get_value(config, "device", json_type_object);
	if (sec_device) {
		if (!process_section_device(iface, sec_device))
			goto err;
	}

	struct json_object *sec_static = neco_json_get_value(config, "static", json_type_object);
	if (sec_static) {
		if (!process_section_static(iface, sec_static))
			goto err;
	}

	return dev;

err:
	interface_free(dev);
	return NULL;
}

static bool interface_set_link_flags(unsigned index, 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 = index;
	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 interface_set_link_state(unsigned index, bool up) {
	return interface_set_link_flags(index, IFF_UP, up ? IFF_UP : 0);
}

static bool interface_set_ipaddr(unsigned index, 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 = index;
	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 void interface_init(device_t *dev) {
	device_interface_t *iface = container_of(dev, device_interface_t, device);

	unsigned index = if_nametoindex(NODE_NAME(dev));
	if (!index)
		return;

	interface_set_link_state(index, true);

	for (size_t i = 0; i < VECTOR_LEN(iface->addrs); i++)
		interface_set_ipaddr(index, &VECTOR_INDEX(iface->addrs, i), true);
}

static void interface_update(device_t *dev) {
}

static void interface_release(device_t *dev) {
	device_interface_t *iface = container_of(dev, device_interface_t, device);

	unsigned index = if_nametoindex(NODE_NAME(dev));
	if (!index)
		return;

	for (size_t i = 0; i < VECTOR_LEN(iface->addrs); i++)
		interface_set_ipaddr(index, &VECTOR_INDEX(iface->addrs, i), false);

	interface_set_link_state(index, false);
}

static device_type_t device_type_interface = {
	.process_config = interface_process_config,
	.free = interface_free,

	.init = interface_init,
	.update = interface_update,
	.release = interface_release,
};

__attribute__((constructor))
static void interface_constructor(void) {
	register_device_type("interface", &device_type_interface);
}