graph.cpp

/*************************************************************************
 ** Copyright (C) 2022 Jan Pedersen <jp@jp-embedded.com>
 ** 
 ** This file is part of tesla-cron.
 ** 
 ** tesla-cron 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 3 of the License, or 
 ** (at your option) any later version.
 ** 
 ** tesla-cron 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 tesla-cron. If not, see <https://www.gnu.org/licenses/>.
 *************************************************************************/
 
#include "graph.h"

#include <rrd.h>
#include <sstream>
#include <fstream>
#include <iostream>
#include <ctime>

bool file_exists(const std::string& name) 
{
	std::ifstream f(name.c_str());
	return f.good();
}

void graph(const std::string &vin, const price_entry &price, int window_level, date::sys_time<std::chrono::system_clock::duration> next_event, const vehicle_data &vd)
{
        const bool vd_ok = vin == vd.vin;

	std::string rrd_path = "/var/tmp";
	std::string rrd_name = rrd_path + "/tesla-" + vin + ".rrd";
	if (!file_exists(rrd_name)) {
		const char *sources[] = {
			"DS:price:GAUGE:90m:-1000:1000",
			"DS:level:GAUGE:90m:-1000:1000",
			"DS:window:GAUGE:90m:-1000:1000",
			"DS:charging:GAUGE:90m:0:1",
			"DS:event:GAUGE:90m:0:1",
			"RRA:MAX:0.5:1m:1w",
			"RRA:AVERAGE:0.5:1m:1w"
		};
                const int source_count = sizeof(sources) / sizeof(sources[0]);
		rrd_create_r(rrd_name.c_str(), 1, std::time(nullptr), source_count, sources);
        }

        char charging = vd_ok ? vd.charge_state.charging_state == "Charging" ? '1' : '0' : 'U';

	auto hour_end = price.time + std::chrono::minutes(60); // current price last until next hour

	// if next event is within 30 min in next hour, extend this hour to that. Otherwise it could be 
	// ignored by next invoke if eg next event is 7:05 and now is 7:10
	if ((next_event > hour_end) && (next_event < hour_end + std::chrono::minutes(30))) {
		hour_end = next_event;
	}

	// do 1 - 3 graphs. 0=event start (if in this hour), 1=event end (if in this hour), 2=hour end
	std::vector<date::sys_time<std::chrono::system_clock::duration>> graph_times;
	if (next_event <= hour_end) {
		graph_times.push_back(next_event - std::chrono::minutes(1)); // event start.
		graph_times.push_back(next_event);                           // event end
	}
        graph_times.push_back(hour_end);

	bool event_on = false;
	for (auto t : graph_times) {
		auto time_sec = std::chrono::duration_cast<std::chrono::seconds>(t.time_since_epoch()).count();
		std::stringstream values;
		values << time_sec << ":" << price.price;
		if (vd_ok) values << ":" << vd.charge_state.battery_level; else values << ":" << 'U';
		values << ":" << window_level;
		values << ":" << charging;
		values << ":" << (event_on ? 1 : 0); // event 0 on first, 1 on second 
		std::string values_str = values.str();
		const char *updateparams[] = { "rrdupdate", rrd_name.c_str(), values_str.c_str() };
		const int param_count = sizeof(updateparams) / sizeof(updateparams[0]);
		int res = rrd_update(param_count, (char**)updateparams);
		if(res !=0) std::cerr << "graph err: " << rrd_get_error() << std::endl;
		rrd_clear_error(); 

		event_on = !event_on;
                window_level = 0; // stop window at event instead of hour end
	}

}