// === Pin Definitions (Only A0–A7 used) ===
#define TRIG_PIN    PA4  // Ultrasonic Trigger
#define ECHO_PIN    PA5  // Ultrasonic Echo

#define BUZZER_PIN  PA6  // Buzzer Output
#define PUMP_PIN    PA7  // Pump Output

#define SOIL1_PIN   PA0  // Soil Moisture Sensor 1
#define SOIL2_PIN   PA1  // Soil Moisture Sensor 2
#define SOIL3_PIN   PA2  // Soil Moisture Sensor 3
#define SOIL4_PIN   PA3  // Soil Moisture Sensor 4

// === Thresholds ===
#define MOISTURE_THRESHOLD      500    // Lower = dry soil
#define WATER_LEVEL_THRESHOLD   10.0   // cm; Higher = water low

// === Variables ===
int dry = 0;
int soilPins[4] = {SOIL1_PIN, SOIL2_PIN, SOIL3_PIN, SOIL4_PIN};
int soilValues[4];

// === Ultrasonic Water Level Function ===
long readWaterLevelCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH, 30000);  // 30ms timeout
  return duration * 0.034 / 2;  // Distance in cm
}

// === Setup ===
void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(PUMP_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  for (int i = 0; i < 4; i++) {
    pinMode(soilPins[i], INPUT);
  }

  digitalWrite(PUMP_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
}

// === Main Loop ===
void loop() {
  long waterLevel = readWaterLevelCM();  // Read tank level (cm)

  if (waterLevel > WATER_LEVEL_THRESHOLD) {
    // Tank is low
    digitalWrite(BUZZER_PIN, HIGH);
    digitalWrite(PUMP_PIN, LOW);
  } else {
    // Tank has enough water
    digitalWrite(BUZZER_PIN, LOW);

    dry = 0;  // Reset dry count

    // Check soil moisture for each sensor
    for (int i = 0; i < 4; i++) {
      soilValues[i] = analogRead(soilPins[i]);
      if (soilValues[i] < MOISTURE_THRESHOLD) {
        dry++;
      }
    }

    // Activate pump if at least one plant is dry
    if (dry > 0) {
      digitalWrite(PUMP_PIN, HIGH);
    } else {
      digitalWrite(PUMP_PIN, LOW);
    }
  }

  delay(4000);  // Check every 4 seconds
}