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

#define PIN_TRIG 5
#define PIN_ECHO 18
#define ON_LED 0
#define ALERT_LED 17
#define TANK_HEIGHT_CM 300  
#define BUZZER_ALARM 23
#define BUZZER_DURATION_MS 5000 
#define LCD_BUTTON 13 // display mode button
#define RST_BUTTON 14  
#define DHT_22 33

LiquidCrystal_I2C lcd(0x27, 16, 2);

DHTesp dhtSensor;

unsigned long buzzerStartTime = 0; 
bool buzzerActive = false; 

bool warningOrNormalDetected = false; 

unsigned long previousMillis = 0; 
const long interval = 500; 

bool ledState = LOW; 

int displayMode = 0; // 0 = water lvl, 1 = temperature, 2 = humidity
unsigned long lastButtonPressTime = 0; // to debounce the button
const long debounceDelay = 50; // debounce delay

void displayStartup() {
  lcd.clear();
  // dynamic dots (...............)
  for (int i = 0; i < 16; i++) { 
    lcd.setCursor(i, 0); 
    lcd.print(".");
    delay(100); // speed of the dots appearing
  }

  delay(200); // Pause before showing the title
  
  lcd.clear();

  String line1 = "WATER TANK";
  int len1 = line1.length();
  int pos1 = (16 - len1) / 2;
  for (int i = 0; i < len1; i++) {
    lcd.setCursor(pos1 + i, 0);
    lcd.print(line1[i]);
    delay(100); 
  }

  String line2 = "MONITORING";
  int len2 = line2.length();
  int pos2 = (16 - len2) / 2;
  for (int i = 0; i < len2; i++) {
    lcd.setCursor(pos2 + i, 1);
    lcd.print(line2[i]);
    delay(100);
  }
  
  delay(1200); 
}

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

  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
  pinMode(ON_LED, OUTPUT);
  pinMode(ALERT_LED, OUTPUT);
  pinMode(BUZZER_ALARM, OUTPUT);
  pinMode(LCD_BUTTON, INPUT_PULLUP);
  pinMode(RST_BUTTON, INPUT_PULLUP);

  digitalWrite(ON_LED, HIGH);
  digitalWrite(ALERT_LED, LOW);
  digitalWrite(BUZZER_ALARM, LOW);

  dhtSensor.setup(DHT_22, DHTesp::DHT22);

  lcd.init(); 
  lcd.backlight(); 
  displayStartup();
  displayMsg("SystemInitialize", "Please wait...");
}

void displayMsg(String message1, String message2) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(message1);
  lcd.setCursor(0, 1);
  lcd.print(message2);
  delay(3000);
}

void displayResetMsg() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("System Resetting");
  lcd.setCursor(0, 1);
  lcd.print("Please wait...");
}

int measureWaterLvl() {
  digitalWrite(PIN_TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  int duration = pulseIn(PIN_ECHO, HIGH);
  return duration * 0.0343 / 2; 
}

int calcWaterLevel(int distanceCM) {
  return distanceCM; 
}

void handleWarningLevel() {
  unsigned long currentMillis = millis(); 
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis; 
    ledState = !ledState; 
    digitalWrite(ALERT_LED, ledState); 
  }
  
  digitalWrite(BUZZER_ALARM, LOW); 
  noTone(BUZZER_ALARM); 
  buzzerActive = false; 
  warningOrNormalDetected = true; 
}

void handleCriticalLevel() {
  digitalWrite(ALERT_LED, HIGH); 
  if (!buzzerActive && warningOrNormalDetected) {
    digitalWrite(BUZZER_ALARM, HIGH);
    tone(BUZZER_ALARM, 1000);
    buzzerStartTime = millis();
    buzzerActive = true; 
    warningOrNormalDetected = false; 
  }
}

void handleNormalLevel() {
  digitalWrite(ALERT_LED, LOW); 
  digitalWrite(BUZZER_ALARM, LOW);
  noTone(BUZZER_ALARM); 
  buzzerActive = false;
  warningOrNormalDetected = true; 
}

void checkBuzzer() {
  if (buzzerActive && (millis() - buzzerStartTime >= BUZZER_DURATION_MS)) {
    noTone(BUZZER_ALARM); 
    buzzerActive = false; 
  }
}

String waterLvlStatus(int waterLevel) {
  if (waterLevel <= 50) { 
    return "CRITICAL";
  } else if (waterLevel <= 150) {
    return "WARNING";
  } else {
    return "NORMAL";
  }
}

String tempStatus(float temperature) {
  if (temperature < 5.0 || temperature > 45.0) {
    return "WARNING";
  } else {
    return "NORMAL";
  }
}

String humStatus(float humidity) {
  if (humidity < 20.0 or humidity > 80.0) {
    return "WARNING";
  } else {
    return "NORMAL";
  }
}

void displayLCD(int waterLevel, float temperature, float humidity) {
  lcd.clear();
  lcd.setCursor(0, 0);
  switch (displayMode) {
    case 0: // display Water Level
      lcd.print("WaterLvl: ");
      lcd.print(waterLevel);
      lcd.print("cm");
      lcd.setCursor(0, 1);
      lcd.print("Status: ");
      lcd.print(waterLvlStatus(waterLevel));
      break;
    case 1: // display Temperature
      lcd.print("Temp: ");
      lcd.print(temperature, 1);
      lcd.print("degC");
      lcd.setCursor(0, 1);
      lcd.print("Status: ");
      lcd.print(tempStatus(temperature));
      break;
    case 2: // display Humidity
      lcd.print("Hum: ");
      lcd.print(humidity, 1);
      lcd.print(" %RH");
      lcd.setCursor(0, 1);
      lcd.print("Status: ");
      lcd.print(humStatus(humidity));
      break;
  }
}

void loop() {

  //cCheck if the reset button is pressed
  int valReset = digitalRead(RST_BUTTON); 
  if (valReset == LOW) { // reset button is pressed
    Serial.println("Reset button pressed! Restarting...");
    displayResetMsg(); // display reset message on the LCD
    ESP.restart(); // perform software reset
  }

// check if button is pressed
  if (digitalRead(LCD_BUTTON) == LOW) {
    unsigned long currentMillis = millis();
    if (currentMillis - lastButtonPressTime > debounceDelay) {
      // button press detected, change display mode
      displayMode = (displayMode + 1) % 3; // Cycle through 0, 1, 2
      lastButtonPressTime = currentMillis;
      //delay(100)
    }
  }

  int distanceCM = measureWaterLvl();
  int waterLevel = calcWaterLevel(distanceCM);
  TempAndHumidity data = dhtSensor.getTempAndHumidity();
  float temperature = data.temperature;
  float humidity = data.humidity;

  displayLCD(waterLevel, temperature, humidity);

  if (waterLevel <= 50) {
    handleCriticalLevel();
  } else if (waterLevel <= 150) { 
    handleWarningLevel();
  } else { 
    handleNormalLevel();
  }

  checkBuzzer();
  delay(300); // main loop delay
  // parameters are updated every 0.3 second, allowing the measurement to be updated in real-time 
}