#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <limits.h>
#include <arpa/inet.h>
#include <string.h>
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <inttypes.h>

#include "main.h"
#include "utils.h"
#include "uring.h"

static unsigned total_malloc_count = 0;
static int malloc_count = 0;

LIST_HEAD(malloc_list);

struct allocation {
	const char *allocfn;
	const char *callerfn;
	int line;
	void *ptr;
	size_t size;
	struct list_head list;
};

static void
add_allocation(const char *allocfn, const char *callerfn, int line, void *ptr, size_t size)
{
	struct allocation *a;

	assert_die(!empty_str(allocfn) && !empty_str(callerfn) && line > 0 && ptr && size > 0, "invalid arguments");

	a = malloc(sizeof(*a));
	if (!a)
		die("malloc: %m");
	a->allocfn = allocfn;
	a->callerfn = callerfn;
	a->line = line;
	a->ptr = ptr;
	a->size = size;
	list_add(&a->list, &malloc_list);
	total_malloc_count++;
	malloc_count++;
	debug(DBG_MALLOC, "called from %s:%i - %s(%zu) = %p (%p)",
	      callerfn, line, allocfn, size, ptr, a);
}

void *
__zmalloc(const char *fn, int line, size_t size)
{
	void *ptr;

	assert_die(!empty_str(fn) && line > 0 && size > 0, "invalid arguments");

	ptr = calloc(1, size);
	if (ptr)
		add_allocation("zmalloc", fn, line, ptr, size);
	return ptr;
}

char *
__xstrdup(const char *fn, int line, const char *s)
{
	char *ptr;

	assert_die(!empty_str(fn) && line > 0 && !empty_str(s), "invalid arguments");

	ptr = strdup(s);
	if (ptr)
		add_allocation("xstrdup", fn, line, ptr, strlen(s) + 1);
	return ptr;
}

char *
__xstrndup(const char *fn, int line, const char *s, size_t n)
{
	char *ptr;

	assert_die(!empty_str(fn) && line > 0 && !empty_str(s) && n > 0, "invalid arguments");

	ptr = strndup(s, n);
	if (ptr)
		add_allocation("xstrndup", fn, line, ptr, n);
	return ptr;
}

void
__xfree(const char *fn, int line, void *ptr)
{
	struct allocation *a, *tmp;
	unsigned delete_count = 0;

	assert_die(!empty_str(fn) && line > 0, "invalid arguments");

	if (!ptr)
		return;
	free(ptr);
	malloc_count--;

	debug(DBG_MALLOC, "called from %s:%i - %p", fn, line, ptr);

	list_for_each_entry_safe(a, tmp, &malloc_list, list) {
		if (a->ptr == ptr) {
			list_del(&a->list);
			free(a);
			delete_count++;
		}
	}

	if (delete_count != 1) {
		error("Delete count is %u for ptr 0x%p", delete_count, ptr);
		exit(EXIT_FAILURE);
	}
}

void
debug_resource_usage()
{
	struct allocation *a;
	DIR *dir;
	struct dirent *dent;
	char buf[4096];
	ssize_t r;
	unsigned file_count = 0;

	debug(DBG_MALLOC, "Still malloced %i (total %u)",
	      malloc_count, total_malloc_count);

	list_for_each_entry(a, &malloc_list, list) {
		debug(DBG_MALLOC, "* Lost allocation - %s:%i - ptr: %p, size: %zu",
		      a->callerfn, a->line, a->ptr, a->size);
	}

	dir = opendir("/proc/self/fd");
	if (!dir) {
		error("failed to open fd dir");
		return;
	}

	debug(DBG_MALLOC, "Open files:");
	while ((dent = readdir(dir)) != NULL) {
		if (streq(dent->d_name, ".") || streq(dent->d_name, ".."))
			continue;

		r = readlinkat(dirfd(dir), dent->d_name, buf, sizeof(buf));
		if (r < 0) {
			debug(DBG_MALLOC, "Failed to readlink %s", dent->d_name);
			continue;
		}
		buf[r] = '\0';
		debug(DBG_MALLOC, " * %s -> %s", dent->d_name, buf);
		file_count++;
	}
	closedir(dir);

	if (file_count > 4)
		debug(DBG_MALLOC, "Lost file descriptor(s)");

	debug(DBG_MALLOC, "CQEs used: %" PRIu64 ", SQEs used: %" PRIu64,
	      cqe_count, sqe_count);
}

void
socket_set_low_latency(int sfd)
{
	int option;

	assert_return(sfd >= 0);

	/* Probably not necessary, but can't hurt */
	if (cfg->socket_defer) {
		option = true;
		if (setsockopt(sfd, SOL_SOCKET, SO_KEEPALIVE, &option, sizeof(option)) < 0)
			error("setsockopt: %m");
	}

	/* Doubtful if it has much effect, but can't hurt */
	if (cfg->socket_iptos) {
		option = IPTOS_LOWDELAY;
		if (setsockopt(sfd, IPPROTO_IP, IP_TOS, &option, sizeof(option)) < 0)
			error("setsockopt: %m");
	}

	/* Nagle's algorithm is a poor fit for gaming */
	if (cfg->socket_nodelay) {
		option = true;
		if (setsockopt(sfd, IPPROTO_TCP, TCP_NODELAY, &option, sizeof(option)) < 0)
			error("setsockopt: %m");
	}
}

void
connection_set_local(struct connection *conn, int fd)
{
	assert_return(conn && fd >= 0);

	conn->local.addrlen = sizeof(conn->local.storage);
	if (getsockname(fd, (struct sockaddr *)&conn->local.storage,
			&conn->local.addrlen) < 0)
		sprintf(conn->local.addrstr, "<unknown>");
	else
		saddr_set_addrstr(&conn->local);
}

void
connection_set_remote(struct connection *conn, struct saddr *remote)
{
	assert_return(conn && remote);

	conn->remote = *remote;
	saddr_set_addrstr(&conn->remote);
}

static void connect_next(struct uring_task *task, struct connection *conn);

static void
connect_cb(struct uring_task *task, int res)
{
	struct connection *conn;

	assert_return(task && task->priv);

	conn = task->priv;
	if (res < 0) {
		debug(DBG_SRV, "%s: connection to %s failed",
		      task->name, conn->remote.addrstr);
		uring_task_close_fd(task);
		connect_next(task, conn);
		return;
	}

	connection_set_local(conn, task->fd);

	debug(DBG_SRV, "%s: connection established %s -> %s",
	      task->name, conn->local.addrstr, conn->remote.addrstr);

	conn->cb(conn, true);
}

static void
connect_next(struct uring_task *task, struct connection *conn)
{
        struct saddr *remote, *tmp;
        int sfd;
        unsigned i;

	assert_return(task && conn && conn->cb);
again:
	assert_task_alive_or(DBG_UR, task, goto out);

	i = 0;
        remote = NULL;
        list_for_each_entry(tmp, conn->addrs, list) {
                if (i == conn->next_addr) {
                        remote = tmp;
                        break;
                }
                i++;
        }

        if (!remote) {
		debug(DBG_SRV, "%s: no more remote addresses to attempt",
		      task->name);
		goto out;
        }

	conn->next_addr++;
	connection_set_remote(conn, remote);
        debug(DBG_SRV, "%s: attempting to connect to %s",
	      task->name, conn->remote.addrstr);

        sfd = socket(conn->remote.storage.ss_family, SOCK_STREAM | SOCK_CLOEXEC, 0);
        if (sfd < 0) {
                error("socket: %m");
                goto again;
        }

	socket_set_low_latency(sfd);

	task->priv = conn;
        uring_task_set_fd(task, sfd);
        uring_connect(task, &conn->remote, connect_cb);
	return;

out:
	conn->cb(conn, false);
}

void
connect_any(struct uring_task *task,
	    struct list_head *addrs, struct connection *conn,
	    connection_cb_t cb)
{
	assert_return(task && addrs && conn && cb);

	conn->next_addr = 0;
	conn->addrs = addrs;
	conn->cb = cb;
	connect_next(task, conn);
}

uint16_t
saddr_port(struct saddr *saddr)
{
	assert_return(saddr, 0);

	switch (saddr->storage.ss_family) {
	case AF_INET:
		return ntohs(saddr->in4.sin_port);
	case AF_INET6:
		return ntohs(saddr->in6.sin6_port);
	default:
		return 0;
	}
}

char *
saddr_addr(struct saddr *saddr, char *buf, size_t len)
{
	assert_return(saddr && buf && len > 0, NULL);

	switch (saddr->storage.ss_family) {
	case AF_INET:
		if (inet_ntop(saddr->in4.sin_family, &saddr->in4.sin_addr, buf, len))
			return buf;
		break;
	case AF_INET6:
		if (inet_ntop(saddr->in6.sin6_family, &saddr->in6.sin6_addr, buf, len))
			return buf;
		break;
	default:
		break;
	}

	snprintf(buf, len, "<unknown>");
	return buf;
}

void
saddr_set_ipv4(struct saddr *saddr, in_addr_t ip, in_port_t port)
{
	assert_return(saddr);

	memset(&saddr->in4, 0, sizeof(saddr->in4));
	saddr->in4.sin_family = AF_INET;
	saddr->in4.sin_port = port;
	saddr->in4.sin_addr.s_addr = ip;
	saddr->addrlen = sizeof(saddr->in4);
	saddr_set_addrstr(saddr);
}

void
saddr_set_ipv6(struct saddr *saddr, const struct in6_addr *ip, in_port_t port)
{
	assert_return(saddr && ip);

	memset(&saddr->in6, 0, sizeof(saddr->in6));
	saddr->in6.sin6_family = AF_INET6;
	saddr->in6.sin6_port = port;
	if (ip)
		saddr->in6.sin6_addr = *ip;
	saddr->addrlen = sizeof(saddr->in6);
	saddr_set_addrstr(saddr);
}

void
saddr_set_addrstr(struct saddr *saddr)
{
	assert_return(saddr);

	char abuf[ADDRSTRLEN];

	switch (saddr->storage.ss_family) {
	case AF_INET:
		snprintf(saddr->addrstr, sizeof(saddr->addrstr),
			 "AF_INET4 %s %" PRIu16,
			 saddr_addr(saddr, abuf, sizeof(abuf)),
			 saddr_port(saddr));
		break;
	case AF_INET6:
		snprintf(saddr->addrstr, sizeof(saddr->addrstr),
			 "AF_INET6 %s %" PRIu16,
			 saddr_addr(saddr, abuf, sizeof(abuf)),
			 saddr_port(saddr));
		break;
	default:
		snprintf(saddr->addrstr, sizeof(saddr->addrstr), "AF_UNKNOWN");
		break;
	}
}

int
strtou16_strict(const char *str, uint16_t *result)
{
	char *end;
	long val;

	assert_return(!empty_str(str) && result, -EINVAL);

	errno = 0;
	val = strtol(str, &end, 10);

	if (errno == ERANGE && (val == LONG_MAX || val == LONG_MIN))
		return -EINVAL;
	
	if (errno != 0 && val == 0)
		return -EINVAL;

	if (end == str)
		return -EINVAL;

	if (*end != '\0')
		return -EINVAL;

	if (val < 1 || val > UINT16_MAX)
		return -EINVAL;

	if (result)
		*result = val;
	return 0;
}