#include <Wire.h>
#include <Keypad.h>
#include <LiquidCrystal.h>
// #include <LiquidCrystal_I2C.h>
// I2C address of the UNO
#define SLAVE_ADDR 8

// pins for external emergency button
const int EMERGENCY_BTN = 2;

// current floor tracker
int currentFloor = 0;

// keypad setup (4 rows × 3 cols)
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C'},
  { '*', '0', '#', 'D'}
};
byte rowPins[ROWS] = { 23, 25, 27, 29 };
byte colPins[COLS] = { 31, 33, 35, 37 };
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// LCD on pins RS, E, D4, D5, D6, D7
LiquidCrystal lcd(12, 11, 6, 5, 4, 3);
// LiquidCrystal_I2C lcd(0x27, 16, 2);  // set the LCD address to 0x3F for a 16 chars and 2 line display


void setup() {
  Wire.begin();  // join I2C as master
  pinMode(EMERGENCY_BTN, INPUT_PULLUP);
  lcd.begin(16, 2);
  //  lcd.init();
  // lcd.clear();
  // lcd.backlight();  // Make sure backlight is on
  // lcd.clear();
  lcd.print("Choose floor:");
}

void loop() {
  // 1) Check emergency button
  if (digitalRead(EMERGENCY_BTN) == LOW) {
    sendCommand(0x02, 0);  // 0x02 = EMERGENCY
    lcd.clear();
    lcd.print("EMERGENCY");
    delay(2000);
    lcd.clear();
    lcd.print("Choose floor:");
    // debounce
    while (digitalRead(EMERGENCY_BTN) == LOW) delay(10);
  }

  // 2) Read floor input
  static String entry = "";
  char k = keypad.getKey();
  if (k) {
    if (k >= '0' && k <= '9') {
      if (entry.length() < 2) {
        entry += k;
        lcd.setCursor(0, 1);
        lcd.print("Floor: " + entry + " ");
      }
    } else if (k == '#') {
      if (entry.length() > 0) {
        int dest = entry.toInt();
        lcd.clear();
        lcd.print("Target: " + String(dest));
        delay(500);

        if (dest == currentFloor) {
          // fault
          sendCommand(0x03, 0);
          lcd.clear();
          lcd.print("Fault!");
          delay(1000);
        } else {
          // normal move
          sendCommand(0x01, dest);
          currentFloor = dest;
        }

        lcd.clear();
        lcd.print("Choose floor:");
      }
      entry = "";
    } else if (k == '*') {
      entry = "";  // clear
      lcd.setCursor(0, 1);
      lcd.print("                ");
    }
  }
}

// helper: send 2-byte command to slave
void sendCommand(byte cmd, byte data) {
  Wire.beginTransmission(SLAVE_ADDR);
  Wire.write(cmd);
  Wire.write(data);
  Wire.endTransmission();
}