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

#define ENTRY_SENSOR 2  
#define EXIT_SENSOR 3   
#define AC_PIN 4        // LED pin for AC control (simulating temperature with PWM)

int occupancyCount = 0;
int acTemperature = 0;  // Temperature of the AC

// Initialize the LCD with I2C address 0x27 and 16 columns x 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
    pinMode(ENTRY_SENSOR, INPUT);
    pinMode(EXIT_SENSOR, INPUT);
    pinMode(AC_PIN, OUTPUT);

    // Initialize the LCD
    lcd.begin(16, 2);
    lcd.print("Fan Control System");
    delay(2000);  // Wait for 2 seconds
    lcd.clear();

    Serial.begin(9600);
}

void loop() {
    static bool entryState = false;
    static bool exitState = false;

    // Detect Entry
    if (digitalRead(ENTRY_SENSOR) == HIGH && !entryState) {
        entryState = true; 
        occupancyCount++;
        Serial.println("Person Entered! Count: " + String(occupancyCount));
    } else if (digitalRead(ENTRY_SENSOR) == LOW) {
        entryState = false;
    }

    // Detect Exit
    if (digitalRead(EXIT_SENSOR) == HIGH && !exitState) {
        exitState = true; 
        if (occupancyCount > 0) {
            occupancyCount--;
        }
        Serial.println("Person Exited! Count: " + String(occupancyCount));
    } else if (digitalRead(EXIT_SENSOR) == LOW) {
        exitState = false;
    }

    // Adjust AC Temperature Based on Occupancy Count
    if (occupancyCount == 0) {
        acTemperature = 0;   // AC OFF (LED OFF)
    } else if (occupancyCount <= 1) {
        acTemperature = 24;  // 1  people → AC at 24°C
    } else if (occupancyCount <= 2) {
        acTemperature = 22;  // 2 people → AC at 22°C
    } else if (occupancyCount <= 9) {
        acTemperature = 20;  // 3 to 6 people → AC at 20°C
    } else {
        acTemperature = 18;  // 6+ people → AC at 18°C
    }

    // Display AC Temperature and Occupancy on LCD
    lcd.setCursor(0, 0);
    lcd.print("Count: ");
    lcd.print(occupancyCount);

    lcd.setCursor(0, 1);
    if (acTemperature == 0) {
        lcd.print("AC: OFF");
    } else {
        lcd.print("AC Temp: ");
        lcd.print(acTemperature);
        lcd.print(" C");
    }

    Serial.print("AC Temperature: ");
    if (acTemperature == 0) {
        Serial.println("OFF");
    } else {
        Serial.println(acTemperature);
    }

    delay(500); // Small delay to update display
}