#include <arpa/inet.h>
#include <netinet/tcp.h>
#include <event2/bufferevent.h>
#include <event2/event.h>
#include <event2/buffer.h>
#include <unistd.h>
#include <assert.h>

#include <tfe_utils.h>
#include <watchdog_kni.h>
#include <MESA/MESA_prof_load.h>

enum watchdog_kni_conn_state
{
	CONN_STATE_DISCONNECT = 0,
	CONN_STATE_CONNECTING = 1,
	CONN_STATE_CONNECTED = 2
};

struct watchdog_kni
{
    struct tfe_proxy * proxy;
    const char * profile;
    void * logger;

    unsigned int enable;
    enum watchdog_kni_conn_state conn_state;

    struct sockaddr_in sk_kni_watchdog;
    struct event_base * ev_base;
    struct bufferevent * bev;
    struct event * ev_retry;
    pthread_t pthread;
    unsigned int retry_times;
};

static void watchdog_kni_eventcb(struct bufferevent *bev, short what, void *ctx);
static void watchdog_kni_readcb(struct bufferevent *bev, void *ctx);

static int watchdog_kni_fd_make_keepalive(int fd)
{
    unsigned int so_keepalive = 1;
    unsigned int tcp_keepcnt = 1;
    unsigned int tcp_keepintvl = 1;
    unsigned int tcp_keepidle = 1;

    evutil_make_socket_nonblocking(fd);

    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (const void *) &so_keepalive, sizeof(int)) == -1)
    {
        TFE_LOG_ERROR(g_default_logger, "watchdog fd setup setsockopt(SO_KEEPALIVE, %d) failed : %s",
            so_keepalive, strerror(errno)); goto errout;
    }

    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, (const void *) &tcp_keepcnt, sizeof(int)) == -1)
    {
        TFE_LOG_ERROR(g_default_logger, "watchdog fd setup setsockopt(TCP_KEEPCNT, %d) failed: %s",
            tcp_keepcnt, strerror(errno)); goto errout;
    }

    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, (const void *) &tcp_keepintvl, sizeof(int)) == -1)
    {
        TFE_LOG_ERROR(g_default_logger, "watchdog fd setup setsockopt(TCP_KEEPINTVL, %d) failed: %s",
            tcp_keepintvl, strerror(errno)); goto errout;
    }

    if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, (const void *) &tcp_keepidle, sizeof(int)) == -1)
	{
		TFE_LOG_ERROR(g_default_logger, "watchdog fd setup setsockopt(TCP_KEEPIDLE, %d) failed: %s",
			tcp_keepidle, strerror(errno)); goto errout;
	}

    return 0;

errout:
    return -1;
}

static void watchdog_kni_readcb(struct bufferevent *bev, void *ctx)
{
	struct evbuffer * evbuffer_in = bufferevent_get_input(bev);
	evbuffer_drain(evbuffer_in, evbuffer_get_length(evbuffer_in));
}

static void watchdog_kni_try_connect(struct watchdog_kni * __ctx)
{
	assert(__ctx->conn_state == CONN_STATE_DISCONNECT);
	bufferevent_socket_connect(__ctx->bev, (const sockaddr *) &__ctx->sk_kni_watchdog, sizeof(__ctx->sk_kni_watchdog));
	bufferevent_setcb(__ctx->bev, watchdog_kni_readcb, NULL, watchdog_kni_eventcb, __ctx);
	bufferevent_enable(__ctx->bev, EV_READ | EV_WRITE);

	char str_kni_addr[INET_ADDRSTRLEN] = {};
	uint16_t kni_port = ntohs(__ctx->sk_kni_watchdog.sin_port);
	inet_ntop(AF_INET, &__ctx->sk_kni_watchdog.sin_addr, str_kni_addr, sizeof(str_kni_addr));

	TFE_LOG_INFO(g_default_logger, "watchdog connecting(retry times: %d) to %s:%u. ",
		__ctx->retry_times, str_kni_addr, kni_port);
}

static void watchdog_kni_reset(struct watchdog_kni * __ctx)
{
	if (__ctx->bev)
	{
		bufferevent_disable(__ctx->bev, EV_READ | EV_WRITE);
		bufferevent_free(__ctx->bev);
	}

	__ctx->bev = bufferevent_socket_new(__ctx->ev_base, -1, BEV_OPT_CLOSE_ON_FREE);
	if (unlikely(__ctx->bev == NULL))
	{
		DIE("Failed at bufferevent_socket_new(), Exit.");
		return;
	}

	__ctx->conn_state = CONN_STATE_DISCONNECT;
}

static void watchdog_kni_retry_cb(evutil_socket_t fd, short what, void *ctx)
{
	struct watchdog_kni * __ctx = (struct watchdog_kni *) ctx;
	watchdog_kni_try_connect(__ctx);
}

static void watchdog_kni_eventcb(struct bufferevent *bev, short what, void *ctx)
{
	struct watchdog_kni * __ctx = (struct watchdog_kni *)ctx;
	if (what & BEV_EVENT_CONNECTED)
	{
		TFE_LOG_INFO(__ctx->bev, "KNI watchdog connection is established.");
		__ctx->conn_state = CONN_STATE_CONNECTED;
		__ctx->retry_times = 0;

		int fd = bufferevent_getfd(bev);
		watchdog_kni_fd_make_keepalive(fd);
		assert(fd >= 0);

		return;
	}

	if (what & (BEV_EVENT_EOF | BEV_EVENT_ERROR | BEV_EVENT_TIMEOUT))
	{
		if (what & BEV_EVENT_TIMEOUT)
		{
			TFE_LOG_ERROR(__ctx->logger, "KNI watchdog connection timeout, KNI is shutdown.");
			goto retry;
		}

		if (what & BEV_EVENT_EOF)
		{
			TFE_LOG_ERROR(__ctx->logger, "KNI watchdog connection broken, KNI is shutdown.");
			goto retry;
		}

		if (what & BEV_EVENT_ERROR)
		{
			TFE_LOG_ERROR(__ctx->logger, "KNI watchdog connection broken: %s.", strerror(errno));
			goto retry;
		}
	}

	return;

retry:
	watchdog_kni_reset(__ctx);
	struct timeval timeval { .tv_sec = 2, .tv_usec = 0};

	/* Free the old retry event and alloc a new retry event */
	if (__ctx->ev_retry)
	{
		event_free(__ctx->ev_retry);
		__ctx->ev_retry = NULL;
	}

	__ctx->ev_retry = event_new(__ctx->ev_base, -1, 0, watchdog_kni_retry_cb, __ctx);
	if (unlikely(__ctx->ev_retry == NULL))
	{
		DIE("Failed at event_new() for retry event.");
		return;
	}

	event_add(__ctx->ev_retry, &timeval);
	__ctx->retry_times++;
}


void * watchdog_kni_thread(void * arg)
{
    struct watchdog_kni * __ctx = (struct watchdog_kni *)arg;
    while(event_base_dispatch(__ctx->ev_base) >= 0) {}
    DIE("watchdog thread is terminated.");
}

struct watchdog_kni * watchdog_kni_create(struct tfe_proxy * proxy, const char * profile, void * logger)
{
	struct watchdog_kni * __ctx = ALLOC(struct watchdog_kni, 1);
	int ret = 0;

	__ctx->proxy = proxy;
	__ctx->profile = profile;
	__ctx->logger = logger;

	unsigned int en_watchdog = 0;
	MESA_load_profile_uint_def(profile, "kni", "watchdog_switch", &en_watchdog, 0);
	__ctx->enable = en_watchdog;

	if (!__ctx->enable)
	{
		return __ctx;
	}

	char str_kni_ip[TFE_STRING_MAX] = {0};
	MESA_load_profile_string_def(profile, "kni", "ip", str_kni_ip, sizeof(str_kni_ip), "127.0.0.1");

	struct sockaddr_in sk_kni_address{};
	sk_kni_address.sin_family = AF_INET;
	ret = inet_pton(AF_INET, str_kni_ip, &sk_kni_address.sin_addr);

	if (ret < 0)
	{
		TFE_LOG_ERROR(logger, "failed at parsing kni's address, in file %s, section %s, entry %s: %s",
			profile, "kni", "ip", str_kni_ip);
		goto __errout;
	}

	unsigned int kni_port;
	MESA_load_profile_uint_def(profile, "kni", "watchdog_port", &kni_port, 2476);

	__ctx->sk_kni_watchdog = sk_kni_address;
	__ctx->sk_kni_watchdog.sin_port = htons(kni_port);
	__ctx->ev_base = event_base_new();
	if (!__ctx->ev_base)
	{
		TFE_LOG_ERROR(logger, "failed at watchdog event_base_new(): %s", strerror(errno));
		goto __errout;
	}

	watchdog_kni_reset(__ctx);
	watchdog_kni_try_connect(__ctx);

	/* Create a thread to dispatch ctx->evbase */
	ret = pthread_create(&__ctx->pthread, NULL, watchdog_kni_thread, (void *) __ctx);
	if (unlikely(ret < 0))
	{
		TFE_LOG_ERROR(__ctx->logger, "Failed at creating watchdog thread: %s", strerror(errno));
		goto __errout;
	}

	TFE_LOG_INFO(__ctx->logger, "KNI watchdog module init successfully.");
	return __ctx;

__errout:
	return NULL;
};