#define TEMPERATURE_SENSOR A14
#define HEATER A4
#define PH_SENSOR_INPUT A13
#define PH_PUMP_ACID A5
#define PH_PUMP_BASE A3
#define STIRRING_PHOTO_SENSOR A8
#define STIRRER RED_LED
double sum = 0;
boolean Heater = false;

void setup() {
  Serial.begin(115200);
  pinMode(STIRRING_PHOTO_SENSOR, OUTPUT);
  pinMode(STIRRER, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  double targetTemperature;
  double targetpH;
  int targetStirringSpeed;
  double currentpH = 0;
  double currentTemperature = readTemperature();
  controlHeater(currentTemperature, targetTemperature);
  int count = 0;
  for(count = 0; count < 10; count++){
      currentpH = readpH(currentTemperature);
      sum = sum + currentpH;
  }
  currentpH = sum / 10;
  controlpHPumps(currentpH, targetpH);

  double currentStirringSpeed = readStirringSpeed();
  controlStirrer(currentStirringSpeed, targetStirringSpeed);
}

double readTemperature() {
    const int Nortemperature = 25;
    const double resistance = 10200;
    const double B = 4220;

    double Thermistor = analogRead(TEMPERATURE_SENSOR);
    Thermistor = (Thermistor * resistance)/(3.3-Thermistor);
    double Reverse_currentTemperature = (log(Thermistor/10000))/B + 1/(Nortemperature);
    return 1/Reverse_currentTemperature;
}

void controlHeater(double currentTemperature, double targetTemperature) {
    if(currentTemperature >= targetTemperature){
        digitalWrite(HEATER, LOW);
        Heater = false;
    }
    else {
         digitalWrite(HEATER, HIGH);
         Heater = true;
    }
}

double readpH(double currentTemperature) {
     float reading = analogRead(PH_SENSOR_INPUT);
     reading = reading * 3 / 1023;
     reading = (reading - 0.4) / (0.0592);
     return reading;
}

void controlpHPumps(double currentpH, double targetpH) {
       if(currentpH > targetpH){
           digitalWrite(PH_PUMP_BASE, LOW);
           digitalWrite(PH_PUMP_ACID, HIGH);
       }
       else if(currentpH == targetpH){
           digitalWrite(PH_PUMP_BASE, LOW);
           digitalWrite(PH_PUMP_ACID, LOW);
       }
       else {
           digitalWrite(PH_PUMP_ACID, LOW);
           digitalWrite(PH_PUMP_BASE, HIGH);
       }
}

bool lastStirringSensorState = false;
long lastTimeSawLight = millis();
int lastStirringSpeedReading = 0;

int readStirringSpeed() {
    int readingAnalog = analogRead(STIRRING_PHOTO_SENSOR);

    bool state = readingAnalog > 600;

    if (lastStirringSensorState != state) {
        if (state) { //We just saw light
            long currentTime = millis();
            int timeForHalfRev = int(currentTime - lastTimeSawLight);
            lastTimeSawLight = currentTime;

            lastStirringSpeedReading = (60*1000)/(timeForHalfRev*2);
            Serial.println(lastStirringSpeedReading);
        }
    }

    lastStirringSensorState = state;

    return lastStirringSpeedReading;
}

int currentStirringPWM = 1;
long lastTimeChangedPWM = 0;

const long PWMChangeTimeout = 100;

void controlStirrer(int currentStirringSpeed, int targetStirringSpeed) {
    if (millis() - lastTimeChangedPWM >= PWMChangeTimeout) {
        lastTimeChangedPWM = millis();

        if (targetStirringSpeed >= currentStirringSpeed) {
            currentStirringPWM++;
        }
        else{
            currentStirringPWM--;
        }
        analogWrite(STIRRER, currentStirringPWM);

    }
}