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

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

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.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 bool process_section_device(device_interface_t *iface, const ini_section_t *section) {
	ini_field_t *field;

	list_for_each_entry(field, &section->fields, node) {
		switch (lookup_keyword(field->key)) {
		default:
			fprintf(stderr, "interface: [Device]: unknown field %s\n", field->key);
		}
	}

	return true;
}

static bool process_section_static(device_interface_t *iface, const ini_section_t *section) {
	ini_field_t *field;

	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 void interface_free_device(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 device_t * interface_process_config(const char *name, const ini_file_t *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;
	}

	const ini_section_t *section;
	list_for_each_entry(section, &config->sections, node) {
		switch (lookup_keyword(section->name)) {
		case KW_Device:
			if (!process_section_device(iface, section))
				goto err;
			break;

		case KW_Static:
			if (!process_section_static(iface, section))
				goto err;
			break;

		default:
			fprintf(stderr, "interface: unknown section %s\n", section->name);
		}
	}

	return dev;

err:
	interface_free_device(dev);
	return NULL;
}

static device_type_t device_type_interface = {
	.process_config = interface_process_config,
	.free_device = interface_free_device,
};

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