/*
 * (C) 2015 by Sysmocom s.f.m.c. GmbH
 *
 * Author: Jacob Erlbeck <jerlbeck@sysmocom.de>
 *
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <osmocom/core/stats.h>

#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <arpa/inet.h>

#include <osmocom/core/utils.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/rate_ctr.h>
#include <osmocom/core/stat_item.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/statistics.h>
#include <osmocom/core/msgb.h>

/* TODO: register properly */
#define DSTATS DLGLOBAL

#define STATS_DEFAULT_INTERVAL 5 /* secs */
#define STATS_DEFAULT_STATSD_BUFLEN 256

static LLIST_HEAD(stats_reporter_list);
static void *stats_ctx = NULL;
static int is_initialised = 0;
static int32_t current_stat_item_index = 0;

static struct stats_config s_stats_config = {
	.interval = STATS_DEFAULT_INTERVAL,
};
struct stats_config *stats_config = &s_stats_config;

static struct osmo_timer_list stats_timer;

static int stats_reporter_statsd_open(struct stats_reporter *srep);
static int stats_reporter_statsd_close(struct stats_reporter *srep);
static int stats_reporter_send(struct stats_reporter *srep, const char *data,
	int data_len);
static int stats_reporter_send_buffer(struct stats_reporter *srep);

static int update_srep_config(struct stats_reporter *srep)
{
	int rc = 0;

	if (srep->type != STATS_REPORTER_STATSD) {
		srep->enabled = 0;
		return -ENOTSUP;
	}

	if (srep->running) {
		rc = stats_reporter_statsd_close(srep);
		srep->running = 0;
	}

	if (!srep->enabled)
		return rc;

	rc = stats_reporter_statsd_open(srep);
	if (rc < 0)
		srep->enabled = 0;
	else
		srep->running = 1;

	return rc;
}

static void stats_timer_cb(void *data)
{
	int interval = stats_config->interval;

	if (!llist_empty(&stats_reporter_list))
		stats_report();

	osmo_timer_schedule(&stats_timer, interval, 0);
}

static int start_timer()
{
	if (!is_initialised)
		return -ESRCH;

	stats_timer.cb = stats_timer_cb;
	osmo_timer_schedule(&stats_timer, 0, 1);

	return 0;
}

struct stats_reporter *stats_reporter_alloc(enum stats_reporter_type type,
	const char *name)
{
	struct stats_reporter *srep;
	srep = talloc_zero(stats_ctx, struct stats_reporter);
	OSMO_ASSERT(srep);
	srep->type = type;
	if (name)
		srep->name = talloc_strdup(srep, name);
	srep->fd = -1;

	llist_add(&srep->list, &stats_reporter_list);

	return srep;
}

void stats_reporter_free(struct stats_reporter *srep)
{
	stats_reporter_disable(srep);
	llist_del(&srep->list);
	talloc_free(srep);
}

void stats_init(void *ctx)
{
	stats_ctx = ctx;
	stat_item_discard_all(&current_stat_item_index);

	is_initialised = 1;
	start_timer();
}

struct stats_reporter *stats_reporter_find(enum stats_reporter_type type,
	const char *name)
{
	struct stats_reporter *srep;
	llist_for_each_entry(srep, &stats_reporter_list, list) {
		if (srep->type != type)
			continue;
		if (srep->name != name) {
			if (name == NULL || srep->name == NULL ||
				strcmp(name, srep->name) != 0)
				continue;
		}
		return srep;
	}
	return NULL;
}

int stats_reporter_set_remote_addr(struct stats_reporter *srep, const char *addr)
{
	int rc;
	struct sockaddr_in *sock_addr = (struct sockaddr_in *)&srep->dest_addr;
	struct in_addr inaddr;

	OSMO_ASSERT(addr != NULL);

	rc = inet_pton(AF_INET, addr, &inaddr);
	if (rc <= 0)
		return -EINVAL;

	sock_addr->sin_addr = inaddr;
	sock_addr->sin_family = AF_INET;
	srep->dest_addr_len = sizeof(*sock_addr);

	talloc_free(srep->dest_addr_str);
	srep->dest_addr_str = talloc_strdup(srep, addr);

	return update_srep_config(srep);
}

int stats_reporter_set_remote_port(struct stats_reporter *srep, int port)
{
	struct sockaddr_in *sock_addr = (struct sockaddr_in *)&srep->dest_addr;

	srep->dest_port = port;
	sock_addr->sin_port = htons(port);

	return update_srep_config(srep);
}

int stats_reporter_set_local_addr(struct stats_reporter *srep, const char *addr)
{
	int rc;
	struct sockaddr_in *sock_addr = (struct sockaddr_in *)&srep->bind_addr;
	struct in_addr inaddr;

	if (addr) {
		rc = inet_pton(AF_INET, addr, &inaddr);
		if (rc <= 0)
			return -EINVAL;
	} else {
		addr = INADDR_ANY;
	}

	sock_addr->sin_addr = inaddr;
	sock_addr->sin_family = AF_INET;
	srep->bind_addr_len = addr ? sizeof(*sock_addr) : 0;

	talloc_free(srep->bind_addr_str);
	srep->bind_addr_str = addr ? talloc_strdup(srep, addr) : NULL;

	return update_srep_config(srep);
}

int stats_reporter_set_mtu(struct stats_reporter *srep, int mtu)
{
	if (mtu < 0)
		return -EINVAL;

	srep->mtu = mtu;

	return update_srep_config(srep);
}

int stats_set_interval(int interval)
{
	if (interval <= 0)
		return -EINVAL;

	stats_config->interval = interval;
	if (is_initialised)
		start_timer();

	return 0;
}

int stats_reporter_set_name_prefix(struct stats_reporter *srep, const char *prefix)
{
	talloc_free(srep->name_prefix);
	srep->name_prefix = prefix ? talloc_strdup(srep, prefix) : NULL;

	return update_srep_config(srep);
}

int stats_reporter_enable(struct stats_reporter *srep)
{
	srep->enabled = 1;

	return update_srep_config(srep);
}

int stats_reporter_disable(struct stats_reporter *srep)
{
	srep->enabled = 0;

	return update_srep_config(srep);
}

static int stats_reporter_send(struct stats_reporter *srep, const char *data,
	int data_len)
{
	int rc;

	rc = sendto(srep->fd, data, data_len, MSG_NOSIGNAL | MSG_DONTWAIT,
		&srep->dest_addr, srep->dest_addr_len);

	if (rc == -1)
		rc = -errno;

	return rc;
}

static int stats_reporter_send_buffer(struct stats_reporter *srep)
{
	int rc;

	if (!srep->buffer || msgb_length(srep->buffer) == 0)
		return 0;

	rc = stats_reporter_send(srep,
		(const char *)msgb_data(srep->buffer), msgb_length(srep->buffer));

	msgb_trim(srep->buffer, 0);

	return rc;
}

/*** statsd reporter ***/

struct stats_reporter *stats_reporter_create_statsd(const char *name)
{
	struct stats_reporter *srep;
	srep = stats_reporter_alloc(STATS_REPORTER_STATSD, name);

	return srep;
}

static int stats_reporter_statsd_open(struct stats_reporter *srep)
{
	int sock;
	int rc;
	int buffer_size = STATS_DEFAULT_STATSD_BUFLEN;

	if (srep->fd != -1)
		stats_reporter_statsd_close(srep);

	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock == -1)
		return -errno;

	if (srep->bind_addr_len > 0) {
		rc = bind(sock, &srep->bind_addr, srep->bind_addr_len);
		if (rc == -1)
			goto failed;
	}

	srep->fd = sock;

	if (srep->mtu > 0) {
		buffer_size = srep->mtu - 20 /* IP */ - 8 /* UDP */;
		srep->agg_enabled = 1;
	}

	srep->buffer = msgb_alloc(buffer_size, "stats buffer");

	return 0;

failed:
	rc = -errno;
	close(sock);

	return rc;
}

static int stats_reporter_statsd_close(struct stats_reporter *srep)
{
	int rc;
	if (srep->fd == -1)
		return -EBADF;

	stats_reporter_send_buffer(srep);

	rc = close(srep->fd);
	srep->fd = -1;
	msgb_free(srep->buffer);
	srep->buffer = NULL;
	return rc == -1 ? -errno : 0;
}

static int stats_reporter_statsd_send(struct stats_reporter *srep,
	const char *name1, int index1, const char *name2, int value,
	const char *unit)
{
	char *buf;
	int buf_size;
	int nchars, rc = 0;
	char *fmt = NULL;
	int old_len = msgb_length(srep->buffer);

	if (name1) {
		if (index1 > 0)
			fmt = "%1$s.%2$s.%6$d.%3$s:%4$d|%5$s";
		else
			fmt = "%1$s.%2$s.%3$s:%4$d|%5$s";
	} else {
		fmt = "%1$s.%2$0.0s%3$s:%4$d|%5$s";
	}
	if (!srep->name_prefix)
		fmt += 5; /* skip prefix part */

	if (srep->agg_enabled) {
		if (msgb_length(srep->buffer) > 0 &&
			msgb_tailroom(srep->buffer) > 0)
		{
			msgb_put_u8(srep->buffer, '\n');
		}
	}

	buf = (char *)msgb_put(srep->buffer, 0);
	buf_size = msgb_tailroom(srep->buffer);

	nchars = snprintf(buf, buf_size, fmt,
		srep->name_prefix, name1, name2,
		value, unit, index1);

	if (nchars >= buf_size) {
		/* Truncated */
		/* Restore original buffer (without trailing LF) */
		msgb_trim(srep->buffer, old_len);
		/* Send it */
		rc = stats_reporter_send_buffer(srep);

		/* Try again */
		buf = (char *)msgb_put(srep->buffer, 0);
		buf_size = msgb_tailroom(srep->buffer);

		nchars = snprintf(buf, buf_size, fmt,
			srep->name_prefix, name1, name2,
			value, unit, index1);

		if (nchars >= buf_size)
			return -EMSGSIZE;
	}

	if (nchars > 0)
		msgb_trim(srep->buffer, msgb_length(srep->buffer) + nchars);

	if (!srep->agg_enabled)
		rc = stats_reporter_send_buffer(srep);

	return rc;
}

static int stats_reporter_statsd_send_counter(struct stats_reporter *srep,
	const struct rate_ctr_group *ctrg,
	const struct rate_ctr_desc *desc,
	int64_t value, int64_t delta)
{
	if (ctrg)
		return stats_reporter_statsd_send(srep,
			ctrg->desc->group_name_prefix,
			ctrg->idx,
			desc->name, delta, "c");
	else
		return stats_reporter_statsd_send(srep,
			NULL, -1,
			desc->name, delta, "c");
}

static int stats_reporter_statsd_send_item(struct stats_reporter *srep,
	const struct stat_item_group *statg,
	const struct stat_item_desc *desc, int value)
{
	return stats_reporter_statsd_send(srep,
		statg->desc->group_name_prefix, statg->idx,
		desc->name, value, desc->unit);
}

/*** generic rate counter support ***/

static int stats_reporter_send_counter(struct stats_reporter *srep,
	const struct rate_ctr_group *ctrg,
	const struct rate_ctr_desc *desc,
	int64_t value, int64_t delta)
{
	int rc;

	switch (srep->type) {
	case STATS_REPORTER_STATSD:
		rc = stats_reporter_statsd_send_counter(srep, ctrg, desc,
			value, delta);
		break;
	}

	return rc;
}

static int rate_ctr_handler(
	struct rate_ctr_group *ctrg, struct rate_ctr *ctr,
	const struct rate_ctr_desc *desc, void *sctx_)
{
	struct stats_reporter *srep;
	int rc;
	int64_t delta = rate_ctr_difference(ctr);

	if (delta == 0)
		return 0;

	llist_for_each_entry(srep, &stats_reporter_list, list) {
		if (!srep->running)
			continue;

		rc = stats_reporter_send_counter(srep, ctrg, desc,
			ctr->current, delta);

		/* TODO: handle rc (log?, inc counter(!)?) or remove it */
	}

	return 0;
}

static int rate_ctr_group_handler(struct rate_ctr_group *ctrg, void *sctx_)
{
	rate_ctr_for_each_counter(ctrg, rate_ctr_handler, sctx_);

	return 0;
}

/*** stat item support ***/

static int stats_reporter_send_item(struct stats_reporter *srep,
	const struct stat_item_group *statg,
	const struct stat_item_desc *desc,
	int32_t value)
{
	int rc;

	switch (srep->type) {
	case STATS_REPORTER_STATSD:
		rc = stats_reporter_statsd_send_item(srep, statg, desc,
			value);
		break;
	}

	return rc;
}

static int stat_item_handler(
	struct stat_item_group *statg, struct stat_item *item, void *sctx_)
{
	struct stats_reporter *srep;
	int rc;
	int32_t idx = current_stat_item_index;
	int32_t value;

	while (stat_item_get_next(item, &idx, &value) > 0) {
		llist_for_each_entry(srep, &stats_reporter_list, list) {
			if (!srep->running)
				continue;

			rc = stats_reporter_send_item(srep, statg,
				item->desc, value);
		}
	}

	return 0;
}

static int stat_item_group_handler(struct stat_item_group *statg, void *sctx_)
{
	stat_item_for_each_item(statg, stat_item_handler, sctx_);
	stat_item_discard_all(&current_stat_item_index);

	return 0;
}

/*** osmo counter support ***/

static int handle_counter(struct osmo_counter *counter, void *sctx_)
{
	struct stats_reporter *srep;
	int rc;
	struct rate_ctr_desc desc = {0};
	/* Fake a rate counter description */
	desc.name = counter->name;
	desc.description = counter->description;

	int delta = osmo_counter_difference(counter);

	if (delta == 0)
		return 0;

	llist_for_each_entry(srep, &stats_reporter_list, list) {
		if (!srep->running)
			continue;

		rc = stats_reporter_send_counter(srep, NULL, &desc,
			counter->value, delta);

		/* TODO: handle rc (log?, inc counter(!)?) */
	}

	return 0;
}


/*** main reporting function ***/

static void flush_all_reporters()
{
	struct stats_reporter *srep;

	llist_for_each_entry(srep, &stats_reporter_list, list) {
		if (!srep->running)
			continue;

		stats_reporter_send_buffer(srep);
	}
}

int stats_report()
{
	osmo_counters_for_each(handle_counter, NULL);
	rate_ctr_for_each_group(rate_ctr_group_handler, NULL);
	stat_item_for_each_group(stat_item_group_handler, NULL);

	flush_all_reporters();

	return 0;
}