/*
 * HydroTank Project - Combined Sketch
 * Board: STM32 Nucleo-C031C6 (Wokwi simulation)
 *
 * Sensors:
 *   pH  - potentiometer on A0
 *   EC  - slide potentiometer on A1
 *   Temp - DS18B20 on D2 (4.7k pull-up to 3.3V)
 *   Level - HC-SR04 ultrasonic on D6 (TRIG) / D7 (ECHO)
 *
 * Actuators (all via relay modules):
 *   relay1 - Cooling      - D4
 *   relay2 - Heater       - D5
 *   relay3 - pH dosing pump - D8
 *   relay4 - Main pump    - D9
 */

#include <OneWire.h>
#include <DallasTemperature.h>

// --- Analog sensors ---
const int phPin = A0;
const int ecPin = A1;

// --- DS18B20 temperature ---
const int tempPin = 2;
OneWire oneWire(tempPin);
DallasTemperature tempSensor(&oneWire);

// --- Actuators ---
const int coolingPin     = 4;  // relay1
const int heaterPin      = 5;  // relay2
const int dosingPumpPin  = 8;  // relay3
const int mainPumpPin    = 9;  // relay4

// --- Ultrasonic level sensor ---
const int trigPin = 6;
const int echoPin = 7;

// --- Non-blocking dosing pump state ---
bool dosingActive = false;
unsigned long dosingStartTime = 0;
unsigned long lastDoseTime = 0;
const unsigned long doseDurationMs  = 1500;   // how long pump runs per dose
const unsigned long doseCooldownMs  = 10000;  // wait between doses

// --- Water level thresholds (tune to your tank once calibrated) ---
const float lowLevelDistanceCM  = 15.0;  // closer than this = tank full-ish
const float highLevelDistanceCM = 25.0;  // farther than this = tank getting low

void setup() {
  Serial.begin(115200);
  delay(1000);

  analogReadResolution(12);
  tempSensor.begin();

  pinMode(coolingPin, OUTPUT);
  pinMode(heaterPin, OUTPUT);
  pinMode(dosingPumpPin, OUTPUT);
  pinMode(mainPumpPin, OUTPUT);
  digitalWrite(coolingPin, LOW);
  digitalWrite(heaterPin, LOW);
  digitalWrite(dosingPumpPin, LOW);
  digitalWrite(mainPumpPin, LOW);

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  Serial.println("HydroTank - Full System Test");
}

float readDistanceCM() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH, 30000);
  if (duration == 0) return -1;

  return duration * 0.0343 / 2.0;
}

// Non-blocking dosing check: call every loop with the current pH
void checkPHDosing(float currentPH) {
  unsigned long now = millis();

  if (dosingActive) {
    if (now - dosingStartTime >= doseDurationMs) {
      digitalWrite(dosingPumpPin, LOW);
      dosingActive = false;
      Serial.println("Dosing pump OFF");
    }
    return;
  }

  if (currentPH < 5.5 && (now - lastDoseTime > doseCooldownMs)) {
    Serial.println("pH low -> dosing pump ON");
    digitalWrite(dosingPumpPin, HIGH);
    dosingActive = true;
    dosingStartTime = now;
    lastDoseTime = now;
  }
}

void loop() {
  // --- pH ---
  int phRaw = analogRead(phPin);
  float simulatedPH = map(phRaw, 0, 4095, 0, 1400) / 100.0;

  // --- EC ---
  int ecRaw = analogRead(ecPin);
  float simulatedEC = map(ecRaw, 0, 4095, 0, 2000) / 100.0;

  // --- Temperature ---
  tempSensor.requestTemperatures();
  float waterTemp = tempSensor.getTempCByIndex(0);

  // --- Water level ---
  float distance = readDistanceCM();

  // --- Print all readings ---
  Serial.print("pH: ");
  Serial.print(simulatedPH, 2);
  Serial.print("  |  EC: ");
  Serial.print(simulatedEC, 2);
  Serial.print("  |  Temp: ");
  Serial.print(waterTemp, 2);
  Serial.print(" C  |  Level dist: ");
  if (distance < 0) {
    Serial.print("no echo");
  } else {
    Serial.print(distance, 1);
    Serial.print(" cm");
  }
  Serial.println();

  // --- Temperature control logic ---
  if (waterTemp > 25.0) {
    Serial.println("ALERT: Water too hot -> cooling ON");
    digitalWrite(coolingPin, HIGH);
    digitalWrite(heaterPin, LOW);
  } else if (waterTemp < 18.0) {
    Serial.println("ALERT: Water too cold -> heater ON");
    digitalWrite(heaterPin, HIGH);
    digitalWrite(coolingPin, LOW);
  } else {
    digitalWrite(coolingPin, LOW);
    digitalWrite(heaterPin, LOW);
  }

  // --- pH dosing pump logic (non-blocking) ---
  checkPHDosing(simulatedPH);

  // --- Main pump logic (placeholder: runs when level distance is high, i.e. tank running low) ---
  // Adjust thresholds once you calibrate against your real tank's empty/full distances.
  if (distance > highLevelDistanceCM) {
    digitalWrite(mainPumpPin, HIGH);
  } else if (distance < lowLevelDistanceCM) {
    digitalWrite(mainPumpPin, LOW);
  }

  delay(1000);
}