#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <wiringPi.h>

int main(int argc, char *argv[]) {
	if(argc < 5) {
		goto err;
	}
	int pin = atoi(argv[1]);
	int period = atoi(argv[2]);
	int thres_on = atoi(argv[3]);
	int thres_off = atoi(argv[4]);

	if(pin == 0 || period == 0 || thres_on == 0 || thres_off == 0) {
		goto err;
	}

	wiringPiSetup();
	pinMode(pin, OUTPUT);
	digitalWrite(pin, HIGH);

	char buf[8];
	FILE *ftemp;
	int temp;
	size_t len;
	int state = 1;
	while(1) {
		ftemp = fopen("/sys/class/hwmon/hwmon0/temp1_input", "r");
		if(ftemp == NULL) {
			temp = 0;
		} else {
			len = fread(buf, 1, 7, ftemp);
			fclose(ftemp);
			ftemp = NULL;
			buf[len] = 0;
			temp = atoi(buf);
		}
		if(temp > thres_on) {
			digitalWrite(pin, HIGH);
			state = 1;
		} else if(state && temp < thres_off) {
			digitalWrite(pin, LOW);
			state = 0;
		}
		sleep(period);
	}

	err:
	printf("Usage: fancontrol <pin wiringPi> <period in seconds> <power on threshold in millicelsius> <power off threshold in millicelsius>\n");
	return 1;
}