// Beer Thermostat

#define STATUS_OFF 0
#define STATUS_ON 1
#define TOGGLE_NOCHANGE 0
#define TOGGLE_ON 1
#define TOGGLE_OFF 2
#define TOGGLE_MALFUNCTION 3

#define WAIT 1000

struct Thermistor
{
  int  base; // *100, see below
  int  diff; // *10 because of floats (10.2, for example->102)
  int  pin;
};

struct Controller
{
  int  relayPin;
  int  thermInvert; // 0 = power on cools, 1 = power on heats
  int  lastRead;
  int  low;
  int  high;
  int  status; // 0=off;1=on
  int  toggle; // 0=nochange; 1=turnedon; 2=turnedoff; 3=malfunction
  int  timer;  // seconds since last status change
  struct Thermistor Therm; // Thermistor
};

Controller Freezer;
Controller Fermenter;

Thermistor ThermA;
Thermistor ThermB;

void setup()
{

  // Thermistor Calibration
  ThermA.base = 22500; // re-calibrate me!
  ThermA.diff = 102;
  ThermA.pin = 0;
  
  ThermB.base = 22500;
  ThermB.diff = 102;
  ThermB.pin = 1;
  
  // Freezer Setup
  Freezer.relayPin = 12;
  Freezer.low = 40; // (10 * ºC)
  Freezer.high = 60; // (10 * ºC)
  Freezer.thermInvert = 0;
  Freezer.status = STATUS_OFF;
  Freezer.toggle = TOGGLE_NOCHANGE;
  Freezer.timer = 0;
  Freezer.Therm = ThermB;
  
  // Fermenter Setup
  Fermenter.relayPin = 11;
  Fermenter.low = 170; // (10 * ºC)
  Fermenter.high = 180; // (10 * ºC)
  Fermenter.thermInvert = 1;
  Fermenter.status = STATUS_OFF;
  Fermenter.toggle = TOGGLE_NOCHANGE;
  Fermenter.timer = 0;
  Fermenter.Therm = ThermA;

  Serial.begin(9600);
  
  pinMode(Freezer.relayPin, OUTPUT);
  pinMode(Fermenter.relayPin, OUTPUT);
}

void loop()
{
  checkTemp(Freezer);
  toggle(Freezer);
  Freezer.timer++;
  doOutput("KEG", Freezer);

  delay(WAIT);

  checkTemp(Fermenter);
  toggle(Fermenter);
  Fermenter.timer++;
  doOutput("FER", Fermenter);

  delay(WAIT);

}

void checkTemp(struct Controller &c)
{
  int span = 20;
  int aRead = 0;
  for (int i = 0; i < span; i++) {
    aRead = aRead + analogRead(c.Therm.pin);
  }
  aRead = aRead / span;
  c.lastRead = (((1024 - aRead) * 100) - c.Therm.base) / c.Therm.diff; // ºC
}

void toggle(struct Controller &c)
{
  c.toggle = TOGGLE_NOCHANGE;
  if (c.lastRead > c.high && c.status != STATUS_ON) {
    // getting too hot
    tooHot(c);
  } else if (c.lastRead < c.low && c.status != STATUS_OFF) {
    // getting too cold
    tooCold(c);
  }
}

void tooCold(struct Controller &c)
{
  if (c.thermInvert) {
    digitalWrite(c.relayPin, HIGH);
    c.status = STATUS_ON;
    c.toggle = TOGGLE_ON;
  } else {
    digitalWrite(c.relayPin, LOW);
    c.status = STATUS_OFF;
    c.toggle = TOGGLE_OFF;
  }
  c.timer = 0;
}

void tooHot(struct Controller &c)
{
  if (c.thermInvert) {
    digitalWrite(c.relayPin, LOW);
    c.status = STATUS_OFF;
    c.toggle = TOGGLE_OFF;
  } else {
    digitalWrite(c.relayPin, HIGH);
    c.status = STATUS_ON;
    c.toggle = TOGGLE_ON;
  }
  c.timer = 0;
}

void doOutput(char name[4], struct Controller &c)
{
  Serial.print(name);
  Serial.print(" ");
  Serial.print(c.lastRead);
  Serial.print(" ");
  Serial.print(c.status);
  Serial.print(" ");
  Serial.print(c.toggle);
  Serial.print(" ");
  Serial.println(c.timer);
}