/*
 * Copyright (C) 2018 "IoT.bzh"
 * Author "Romain Forlot" <romain.forlot@iot.bzh>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *	 http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#include "influxdb.h"

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <systemd/sd-event.h>

#include "../utils/list.h"

void fill_tag_n_fields(void *c, json_object *columnJ)
{
	int length = json_object_get_string_len(columnJ);
	const char *column = json_object_get_string(columnJ);
	struct series_columns_t *s_col = (struct series_columns_t *)c;

	if(strncasecmp(&column[length-1], "_t", 2) == 0) {
		add_key(s_col->tags, column);
	}
	else if(strncasecmp(&column[length-1], "_f", 2) == 0) {
		add_key(s_col->fields, column);
	}
	return;
}

void unpack_metric_from_db(void *series_processed, json_object *metricJ)
{
	const char *name;
	int length = 0;
	struct series_columns_t col = {.tags = NULL, .fields = NULL};
	json_object *columnsJ = NULL, *valuesJ = NULL;

	if(wrap_json_unpack(metricJ, "{ss, so, so!}",
					 "name", &name,
					 "columns", &columnsJ,
					 "values", &valuesJ)) {
		AFB_ERROR("Unpacking metric goes wrong");
		return;
	 }

	length = json_object_get_string_len(columnsJ);
	wrap_json_array_for_all(columnsJ, fill_tag_n_fields, &col);

	/* Increment counter of series well processed */
	++*((int*)series_processed);
}

int unpack_series(json_object *seriesJ)
{
	size_t series_processed = 0;
	wrap_json_array_for_all(seriesJ, unpack_metric_from_db, (void*)&series_processed);

	return 0;
}

void forward_to_garner(const char *result, size_t size)
{
	int id = 0;

	json_object *resultsJ = NULL,
				*seriesJ = NULL,
				*db_dumpJ = json_tokener_parse(result);
	if( wrap_json_unpack(db_dumpJ, "{so!}",
					 "results", &resultsJ) ||
		wrap_json_unpack(resultsJ, "[{si,so!}]",
					 "statement_id", &id,
					 "series", &seriesJ)) {
		AFB_ERROR("Unpacking results from influxdb request. Request results was:\n%s", result);
		return;
	}

	if(seriesJ)
		unpack_series(seriesJ);
}

void influxdb_read_curl_cb(void *closure, int status, CURL *curl, const char *result, size_t size)
{
	long rep_code = curl_wrap_response_code_get(curl);
	switch(rep_code) {
		case 200:
			AFB_DEBUG("Read correctly done");
			forward_to_garner(result, size);
			break;
		case 400:
			AFB_ERROR("Unacceptable request. %s", result);
			break;
		case 401:
			AFB_ERROR("Invalid authentication. %s", result);
			break;
		default:
			AFB_ERROR("Unexptected behavior. %s", result);
			break;
	}
}

CURL *make_curl_query_get(const char *url)
{
	CURL *curl;
	char *args[5];
	char query[255] = {};
	char last_ts[30] = {};
	char *now;
	int length_now;

	args[0] = "epoch";
	args[1] = "ns";
	args[2] = "q";
	strncat(query, "SELECT * FROM /^.*$/", strlen("SELECT * FROM /^.*$/"));
	args[4] = NULL;
	length_now = asprintf(&now, "%lu", get_ts());

	int rootdir_fd = afb_daemon_rootdir_get_fd();
	int fd_last_read = openat(rootdir_fd, "last_db_read", O_CREAT | O_RDWR, S_IRWXU);
	if (fd_last_read < 0)
		return NULL;

	/* Reading last timestamp recorded and get metric from that point until now
	   else write the last timestamp */
	if(read(fd_last_read, last_ts, sizeof(last_ts)) == 0) {
		if(write(fd_last_read, now, length_now) != length_now)
			AFB_ERROR("Error writing last_db_read file: %s\n", strerror( errno ));
	}
	else {
		strncat(query, " WHERE time >= ", strlen(" WHERE time >= "));
		strncat(query, last_ts, strlen(last_ts));
		close(fd_last_read);
		fd_last_read = openat(rootdir_fd, "last_db_read", O_TRUNC | O_RDWR);
		if (write(fd_last_read, now, length_now) != length_now)
			AFB_ERROR("Error writing last_db_read file: %s", strerror( errno ));
	}

	args[3] = query;
	curl = curl_wrap_prepare_get(url, NULL, (const char * const*)args);

	return curl;
}

int influxdb_read(sd_event_source *s, uint64_t usec, void *userdata)
{
	CURL *curl;
	struct reader_args *a = NULL;
	if(userdata)
		a = (struct reader_args*)userdata;
	else
		return ERROR;

	char url[URL_MAXIMUM_LENGTH]; /* Safe limit for most popular web browser */

	make_url(url, sizeof(url), a->host, a->port, "query");
	curl = make_curl_query_get(url);
	curl_wrap_do(curl, influxdb_read_curl_cb, NULL);

	/* Reschedule next run */
	sd_event_source_set_time(s, usec + a->delay);

	return 0;
}

int influxdb_reader(void *args)
{
	int err = 0;
	uint64_t usec;
	struct sd_event_source *evtSource = NULL;

	/* Set a cyclic cb call each 1s to call the read callback */
	sd_event_now(afb_daemon_get_event_loop(), CLOCK_MONOTONIC, &usec);
	err = sd_event_add_time(afb_daemon_get_event_loop(), &evtSource, CLOCK_MONOTONIC, usec+1000000, 250, influxdb_read, args);
	if(!err)
		err = sd_event_source_set_enabled(evtSource, SD_EVENT_ON);

	return err;
}