#define BLYNK_TEMPLATE_ID "TMPL6reEdDVm7"
#define BLYNK_TEMPLATE_NAME "Water Level Monitoring System"
#define BLYNK_AUTH_TOKEN    "Dw2k-uSHD98hBKYkYcUGvHtYt0m88U6l"

#include <WiFi.h>
#include <BlynkSimpleEsp32.h>

// WiFi Credentials
char ssid[] = "Wokwi-GUEST";
char pass[] = "";

// ===== PIN SETUP =====
#define TRIG_PIN 5
#define ECHO_PIN 18
#define VALVE_LED 22   // simulate solenoid valve
#define BUZZER 21

BlynkTimer timer;

// Variables
long duration;
float distance;
int displayLevel;
bool manualOverride = false;

// TANK CONFIGURATION (Adjust these values based on your physical tank)
const int TANK_EMPTY_DISTANCE = 20; // Distance in cm when tank is empty
const int TANK_FULL_DISTANCE = 2;   // Distance in cm when tank is full

// ===== MANUAL CONTROL FROM BLYNK =====
// V2 is a Switch Widget in the Blynk App
BLYNK_WRITE(V2) {
  manualOverride = param.asInt();
}

// ===== SENSOR + CONTROL FUNCTION =====
void sendSensorData() {
  // 1. Ultrasonic trigger pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // 2. Read echo duration
  duration = pulseIn(ECHO_PIN, HIGH, 30000);
  
  // 3. Calculate distance in cm
  distance = duration * 0.034 / 2;

  // 4. INVERSE MAPPING
  // This converts distance (20cm to 2cm) into a percentage (0% to 100%)
  // constrain() ensures we don't get negative percentages or values over 100
  float clampedDistance = constrain(distance, TANK_FULL_DISTANCE, TANK_EMPTY_DISTANCE);
  displayLevel = map(clampedDistance, TANK_EMPTY_DISTANCE, TANK_FULL_DISTANCE, 0, 100);

  // 5. Send Data to Blynk
  Blynk.virtualWrite(V0, displayLevel); // V0: Gauge or Level Widget (0-100)
  
  // Debugging output to Serial Monitor
  Serial.print("Raw Distance: ");
  Serial.print(distance);
  Serial.print(" cm | Level: ");
  Serial.print(displayLevel);
  Serial.println("%");

  // ===== CONTROL LOGIC =====
  if (!manualOverride) {
    if (distance > 18) {
      // LOW LEVEL (Empty) → OPEN VALVE
      digitalWrite(VALVE_LED, HIGH);
      digitalWrite(BUZZER, LOW);
      Blynk.virtualWrite(V1, 1); // V1: LED Widget for Valve Status
      Serial.println("STATUS: LOW - Valve ON");
    } 
    else if (distance > 5) {
      // MEDIUM LEVEL → KEEP VALVE OPEN
      digitalWrite(VALVE_LED, HIGH);
      digitalWrite(BUZZER, LOW);
      Blynk.virtualWrite(V1, 1);
      Serial.println("STATUS: MEDIUM - Valve ON");
    } 
    else {
      // FULL LEVEL → CLOSE VALVE & ALERT
      digitalWrite(VALVE_LED, LOW);
      digitalWrite(BUZZER, HIGH); // Alarm sounds when full
      Blynk.virtualWrite(V1, 0);
      Serial.println("STATUS: FULL - Valve OFF / ALARM ON");
    }
  } 
  else {
    // MANUAL OVERRIDE (Force Valve ON)
    digitalWrite(VALVE_LED, HIGH);
    digitalWrite(BUZZER, LOW);
    Blynk.virtualWrite(V1, 1);
    Serial.println("STATUS: MANUAL MODE - Valve ON");
  }

  Serial.println("----------------------");
}

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

  // Pin Modes
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(VALVE_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  // Initialize Blynk
  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  // Setup timer to run every 1 second
  timer.setInterval(1000L, sendSensorData);
}

void loop() {
  Blynk.run();
  timer.run();
}