/*
  ESP32-S3 Flood Detector - Wokwi Simulation

  Components:
  - ESP32-S3 DevKitC-1
  - HC-SR04 ultrasonic sensor
  - I2C LCD 16x2
  - SG90 servo motor
  - Piezo buzzer
  - 4 LEDs:
    Red    = DANGER
    Orange = MEDIUM
    Yellow = LOW
    Green  = SAFE

  Water height formula:
  waterHeight = 335 - distanceInCm
*/

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>

// ---------- ESP32-S3 GPIO PINS ----------
const int TRIG_PIN = 4;
const int ECHO_PIN = 5;

const int BUZZER_PIN = 6;
const int SERVO_PIN = 7;

const int LCD_SDA_PIN = 8;
const int LCD_SCL_PIN = 9;

const int RED_LED_PIN = 10;
const int ORANGE_LED_PIN = 11;
const int YELLOW_LED_PIN = 12;
const int GREEN_LED_PIN = 13;

// ---------- OBJECTS ----------
LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo floodServo;

// ---------- VARIABLES ----------
float distanceInCm = -1;
float waterHeight = 0;

String currentStatus = "";
String previousStatus = "";

// Used to make the danger buzzer beep continuously
unsigned long lastBuzzerChange = 0;
bool buzzerOn = false;

// ---------- FUNCTION DECLARATIONS ----------
float readDistanceCM();
void turnOffAllLEDs();
void updateOutputs();
void updateLCD();
void updateBuzzer();
void telegramSimulation();

// ---------- SETUP ----------
void setup() {
  Serial.begin(115200);

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(BUZZER_PIN, OUTPUT);

  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(ORANGE_LED_PIN, OUTPUT);
  pinMode(YELLOW_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT);

  digitalWrite(TRIG_PIN, LOW);
  turnOffAllLEDs();
  noTone(BUZZER_PIN);

  // LCD I2C pins
  Wire.begin(LCD_SDA_PIN, LCD_SCL_PIN);

  lcd.init();
  lcd.backlight();
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Flood Detector");
  lcd.setCursor(0, 1);
  lcd.print("ESP32-S3 Ready");

  // SG90 servo configuration
  floodServo.setPeriodHertz(50);
  floodServo.attach(SERVO_PIN, 500, 2400);
  floodServo.write(0);

  delay(1500);

  Serial.println();
  Serial.println("=================================");
  Serial.println("ESP32-S3 FLOOD DETECTOR STARTED");
  Serial.println("Change HC-SR04 distance in Wokwi");
  Serial.println("300 cm = SAFE");
  Serial.println("200 cm = LOW");
  Serial.println("120 cm = MEDIUM");
  Serial.println("50 cm  = DANGER");
  Serial.println("=================================");
}

// ---------- LOOP ----------
void loop() {
  // Read ultrasonic distance
  distanceInCm = readDistanceCM();

  // Handle sensor errors
  if (distanceInCm < 0) {
    currentStatus = "SENSOR ERROR";

    turnOffAllLEDs();
    floodServo.write(0);

    noTone(BUZZER_PIN);
    buzzerOn = false;

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("SENSOR ERROR");
    lcd.setCursor(0, 1);
    lcd.print("Check HC-SR04");

    Serial.println("Sensor Error: No valid reading.");

    if (currentStatus != previousStatus) {
      telegramSimulation();
      previousStatus = currentStatus;
    }

    delay(500);
    return;
  }

  // Calculate water height using your original formula
  waterHeight = 335 - distanceInCm;

  // Decide flood status
  if (distanceInCm > 240) {
    currentStatus = "SAFE";
  }
  else if (distanceInCm > 160) {
    currentStatus = "LOW";
  }
  else if (distanceInCm > 80) {
    currentStatus = "MEDIUM";
  }
  else {
    currentStatus = "DANGER";
  }

  // Control all outputs
  updateOutputs();
  updateBuzzer();
  updateLCD();

  // Print information in the Wokwi Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distanceInCm, 1);
  Serial.print(" cm | Height: ");
  Serial.print(waterHeight, 1);
  Serial.print(" cm | Status: ");
  Serial.println(currentStatus);

  // Simulated Telegram alert when status changes
  if (currentStatus != previousStatus) {
    telegramSimulation();
    previousStatus = currentStatus;
  }

  delay(250);
}

// ---------- HC-SR04 FUNCTION ----------
float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);

  digitalWrite(TRIG_PIN, LOW);

  unsigned long duration = pulseIn(ECHO_PIN, HIGH, 30000);

  if (duration == 0) {
    return -1;
  }

  float distance = duration * 0.0343 / 2.0;

  if (distance < 2 || distance > 400) {
    return -1;
  }

  return distance;
}

// ---------- LED FUNCTION ----------
void turnOffAllLEDs() {
  digitalWrite(RED_LED_PIN, LOW);
  digitalWrite(ORANGE_LED_PIN, LOW);
  digitalWrite(YELLOW_LED_PIN, LOW);
  digitalWrite(GREEN_LED_PIN, LOW);
}

// ---------- LED AND SERVO CONTROL ----------
void updateOutputs() {
  turnOffAllLEDs();

  if (currentStatus == "SAFE") {
    digitalWrite(GREEN_LED_PIN, HIGH);
    floodServo.write(0);
  }
  else if (currentStatus == "LOW") {
    digitalWrite(YELLOW_LED_PIN, HIGH);
    floodServo.write(30);
  }
  else if (currentStatus == "MEDIUM") {
    digitalWrite(ORANGE_LED_PIN, HIGH);
    floodServo.write(60);
  }
  else if (currentStatus == "DANGER") {
    digitalWrite(RED_LED_PIN, HIGH);
    floodServo.write(90);
  }
}

// ---------- BUZZER CONTROL ----------
void updateBuzzer() {
  // Buzzer only operates in DANGER status
  if (currentStatus != "DANGER") {
    noTone(BUZZER_PIN);
    buzzerOn = false;
    return;
  }

  // Danger alarm pattern:
  // 250 ms sound, 250 ms silence, repeat.
  if (millis() - lastBuzzerChange >= 250) {
    lastBuzzerChange = millis();

    if (buzzerOn) {
      noTone(BUZZER_PIN);
      buzzerOn = false;
    } else {
      tone(BUZZER_PIN, 2000);
      buzzerOn = true;
    }
  }
}

// ---------- LCD DISPLAY ----------
void updateLCD() {
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Height:");
  lcd.print(waterHeight, 1);
  lcd.print("cm");

  lcd.setCursor(0, 1);

  if (currentStatus == "SAFE") {
    lcd.print("Status: SAFE");
  }
  else if (currentStatus == "LOW") {
    lcd.print("Status: LOW");
  }
  else if (currentStatus == "MEDIUM") {
    lcd.print("Status: MEDIUM");
  }
  else if (currentStatus == "DANGER") {
    lcd.print("Status: DANGER!");
  }
}

// ---------- TELEGRAM SIMULATION ----------
void telegramSimulation() {
  Serial.println();
  Serial.println("------ TELEGRAM SIMULATION ------");

  if (currentStatus == "SAFE") {
    Serial.println("SAFE: Water level is normal.");
    Serial.println("Green LED ON | Servo: 0 degrees");
  }
  else if (currentStatus == "LOW") {
    Serial.println("LOW: Water level is increasing.");
    Serial.println("Yellow LED ON | Servo: 30 degrees");
  }
  else if (currentStatus == "MEDIUM") {
    Serial.println("MEDIUM: Water level is rising.");
    Serial.println("Orange LED ON | Servo: 60 degrees");
  }
  else if (currentStatus == "DANGER") {
    Serial.println("DANGER! FLOOD RISK DETECTED!");
    Serial.println("Red LED ON | Servo: 90 degrees");
    Serial.println("Buzzer alarm: ON (beep-beep pattern)");
    Serial.println("Take action immediately.");
  }
  else {
    Serial.println("SYSTEM ERROR: Ultrasonic sensor issue.");
  }

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