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

#define PIR_PIN 33
#define BUZZER_PIN 32
#define FAN_RELAY_PIN 25
#define LIGHT_RELAY_PIN 26
#define BUTTON_UP_PIN 14
#define BUTTON_DOWN_PIN 12

LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16x2 display

int peopleCount = 0;
int maxPeople = 10; // Default maximum people allowed
unsigned long buzzerStartTime = 0;
bool buzzerOn = false;
bool buzzerTriggered = false; // New flag to track if the buzzer has already been triggered

// States for input transition detection
bool pirState = LOW;
bool lastPirState = LOW;

// Button states
bool buttonUpState = HIGH;
bool lastButtonUpState = HIGH;

bool buttonDownState = HIGH;
bool lastButtonDownState = HIGH;

// Timer for PIR state
unsigned long pirLowStartTime = 0;
bool pirWasLow = false; // Track if PIR was previously low
bool exitout = false;

void setup() {
  Serial.begin(115200); // Start serial communication for debugging

  pinMode(PIR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(FAN_RELAY_PIN, OUTPUT);
  pinMode(LIGHT_RELAY_PIN, OUTPUT);
  pinMode(BUTTON_UP_PIN, INPUT_PULLUP);
  pinMode(BUTTON_DOWN_PIN, INPUT_PULLUP);

  digitalWrite(FAN_RELAY_PIN, LOW); // Initially fan is off
  digitalWrite(LIGHT_RELAY_PIN, LOW); // Initially light is off
  digitalWrite(BUZZER_PIN, LOW); // Initially buzzer is off
  
  lcd.init();
  lcd.backlight();
  updateDisplay();
  
  Serial.println("Setup complete. Initial state:");
  Serial.print("People Count: "); Serial.println(peopleCount);
  Serial.print("Max People: "); Serial.println(maxPeople);
}

void loop() {
  handlePeopleCounting();
  handleMaxPeopleAdjustment();
  handleUtilitiesControl();
  handleBuzzer();
}

void handlePeopleCounting() {
  pirState = digitalRead(PIR_PIN);  // Read PIR sensor state
  
  // Detect transition from LOW to HIGH (person entering)
  if (pirState != lastPirState) {
    if (pirState == HIGH) {
      Serial.println("PIR detected motion (HIGH).");
      if (peopleCount < maxPeople && !exitout) {
        peopleCount++;
        Serial.print("People count increased: "); Serial.println(peopleCount);
        updateDisplay();
      }
      if (peopleCount > 0 && exitout) {
        peopleCount--; // Decrease count after 10 seconds of being LOW
        Serial.print("People count decreased (exitout): "); Serial.println(peopleCount);
        updateDisplay();
        if (peopleCount == 0) {
          exitout = false;
        }
      }
      // Reset the low timer since we detected motion
      pirWasLow = false; 
    } else { // pirState is LOW
      Serial.println("PIR detected no motion (LOW), starting timer.");
      pirLowStartTime = millis(); // Start the timer for low state
      pirWasLow = true;
      for(int ii = 0; ii < 2; ii++) {
         tone(BUZZER_PIN, 1000);
         delay(100);
         noTone(BUZZER_PIN);
         delay(100);
      }
    }
    lastPirState = pirState; // Update last PIR state
  }

  // Check if PIR has been LOW for 10 seconds
  if (pirWasLow && (millis() - pirLowStartTime >= 10000)) {
    Serial.println("PIR has been LOW for 10 seconds, enabling exitout.");
    exitout = true;
    pirWasLow = false; // Reset low state tracking
  }
}

void handleMaxPeopleAdjustment() {
  buttonUpState = digitalRead(BUTTON_UP_PIN);
  buttonDownState = digitalRead(BUTTON_DOWN_PIN);

  // Detect button press (transition from HIGH to LOW)
  if (buttonUpState != lastButtonUpState && buttonUpState == LOW) {
    maxPeople++;
    Serial.print("Max people increased: "); Serial.println(maxPeople);
    updateDisplay();
    lastButtonUpState = buttonUpState;  // Update last button up state
  }
  if (buttonDownState != lastButtonDownState && buttonDownState == LOW && maxPeople > 1) {
    maxPeople--;
    Serial.print("Max people decreased: "); Serial.println(maxPeople);
    updateDisplay();
    lastButtonDownState = buttonDownState;  // Update last button down state
  }

  // Update states for debouncing purposes
  lastButtonUpState = buttonUpState;
  lastButtonDownState = buttonDownState;
}

void handleUtilitiesControl() {
  if (peopleCount > 0) {
    digitalWrite(FAN_RELAY_PIN, HIGH); // Turn on fan
    digitalWrite(LIGHT_RELAY_PIN, HIGH); // Turn on light
  } else {
    digitalWrite(FAN_RELAY_PIN, LOW); // Turn off fan
    digitalWrite(LIGHT_RELAY_PIN, LOW); // Turn off light
  }
}

void handleBuzzer() {
  if (peopleCount >= maxPeople && !buzzerTriggered) {
    buzzerOn = true;
    buzzerTriggered = true; // Set buzzerTriggered to true to avoid re-triggering
    buzzerStartTime = millis();
    tone(BUZZER_PIN, 1000);
    Serial.println("Buzzer ON (room full).");
  }

  if (buzzerOn && millis() - buzzerStartTime >= 2000) {
    buzzerOn = false;
    noTone(BUZZER_PIN);
    Serial.println("Buzzer OFF (2 seconds passed).");
  }

  // Reset the buzzer trigger if people count goes below maxPeople
  if (peopleCount < maxPeople) {
    buzzerTriggered = false;
  }
}

void updateDisplay() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("People: ");
  lcd.print(peopleCount);
  lcd.setCursor(0, 1);
  lcd.print("Max: ");
  lcd.print(maxPeople);

  // Debug output for the display
  Serial.print("LCD Update - People: "); Serial.print(peopleCount);
  Serial.print(", Max People: "); Serial.println(maxPeople);
}