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

// ===== LCD 20x4 I2C =====
// En Wokwi suele funcionar 0x27. Si no, prueba 0x3F.
LiquidCrystal_I2C lcd(0x27, 20, 4);

// ===== Keypad 4x4 =====
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' }
};

// Pines según diagram.json
byte rowPins[ROWS] = { 13, 12, 14, 27 };
byte colPins[COLS] = { 26, 25, 33, 32 };

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// ===== Menú / Estados =====
enum Screen {
  SCR_HOME = 0,
  SCR_MENU,
  SCR_PIN,
  SCR_INFO
};

Screen screen = SCR_HOME;

int menuIndex = 0;
const int MENU_COUNT = 3;
const char* menuItems[MENU_COUNT] = {
  "1) Estado GPIO",
  "2) Ingresar PIN",
  "3) Info sistema"
};

String pinBuffer = "";
const String correctPIN = "1234";

// ===== Helpers =====
void lcdClearLine(int row) {
  lcd.setCursor(0, row);
  for (int i = 0; i < 20; i++) lcd.print(' ');
}

void drawHome() {
  lcd.clear();
  lcd.setCursor(0,0); lcd.print("ESP32 + LCD20x4");
  lcd.setCursor(0,1); lcd.print("Keypad 4x4 Wokwi");
  lcd.setCursor(0,2); lcd.print("D=Menu   C=Info");
  lcd.setCursor(0,3); lcd.print("A/B navega dentro");
}

void drawMenu() {
  lcd.clear();
  lcd.setCursor(0,0); lcd.print("== MENU (A/B) ==");
  // Mostramos 2 items por pantalla
  int first = menuIndex;
  int second = (menuIndex + 1) % MENU_COUNT;

  lcd.setCursor(0,1); lcd.print("> "); lcd.print(menuItems[first]);
  lcd.setCursor(0,2); lcd.print("  "); lcd.print(menuItems[second]);

  lcd.setCursor(0,3); lcd.print("D=Sel  C=Atras");
}

void drawPin() {
  lcd.clear();
  lcd.setCursor(0,0); lcd.print("== INGRESAR PIN ==");
  lcd.setCursor(0,1); lcd.print("PIN: ");
  lcd.setCursor(5,1);
  for (size_t i = 0; i < pinBuffer.length(); i++) lcd.print('*');

  lcd.setCursor(0,2); lcd.print("*=Borrar  #=OK");
  lcd.setCursor(0,3); lcd.print("C=Atras");
}

void drawInfo() {
  lcd.clear();
  lcd.setCursor(0,0); lcd.print("== INFO ==");
  lcd.setCursor(0,1); lcd.print("ESP32 DevKit (sim)");
  lcd.setCursor(0,2); lcd.print("I2C SDA=21 SCL=22");
  lcd.setCursor(0,3); lcd.print("C=Atras");
}

void showToast(const String& msg) {
  lcdClearLine(3);
  lcd.setCursor(0,3);
  lcd.print(msg.substring(0, 20));
}

void setup() {
  Wire.begin(21, 22);
  lcd.init();
  lcd.backlight();

  drawHome();
}

void loop() {
  char k = keypad.getKey();
  if (!k) return;

  // Teclas recomendadas:
  // A = arriba / anterior
  // B = abajo / siguiente
  // C = back
  // D = enter / menu

  if (screen == SCR_HOME) {
    if (k == 'D') { screen = SCR_MENU; menuIndex = 0; drawMenu(); }
    else if (k == 'C') { screen = SCR_INFO; drawInfo(); }
    return;
  }

  if (screen == SCR_MENU) {
    if (k == 'A') {
      menuIndex = (menuIndex - 1 + MENU_COUNT) % MENU_COUNT;
      drawMenu();
    } else if (k == 'B') {
      menuIndex = (menuIndex + 1) % MENU_COUNT;
      drawMenu();
    } else if (k == 'C') {
      screen = SCR_HOME;
      drawHome();
    } else if (k == 'D') {
      // Selección
      if (menuIndex == 0) {
        lcd.clear();
        lcd.setCursor(0,0); lcd.print("== ESTADO GPIO ==");
        lcd.setCursor(0,1); lcd.print("GPIO 2: (demo)");
        lcd.setCursor(0,2); lcd.print("No hardware real");
        lcd.setCursor(0,3); lcd.print("C=Atras");
        screen = SCR_INFO; // reutilizamos pantalla simple
      } else if (menuIndex == 1) {
        pinBuffer = "";
        screen = SCR_PIN;
        drawPin();
      } else if (menuIndex == 2) {
        screen = SCR_INFO;
        drawInfo();
      }
    }
    return;
  }

  if (screen == SCR_PIN) {
    if (k == 'C') {
      screen = SCR_MENU;
      drawMenu();
      return;
    }
    if (k >= '0' && k <= '9') {
      if (pinBuffer.length() < 8) pinBuffer += k;
      drawPin();
      return;
    }
    if (k == '*') {
      if (pinBuffer.length() > 0) pinBuffer.remove(pinBuffer.length() - 1);
      drawPin();
      return;
    }
    if (k == '#') {
      if (pinBuffer == correctPIN) {
        showToast("PIN OK! Acceso granted");
      } else {
        showToast("PIN incorrecto");
      }
      delay(700);
      drawPin();
      return;
    }
    return;
  }

  // SCR_INFO o pantallas simples: C regresa
  if (screen == SCR_INFO) {
    if (k == 'C') {
      screen = SCR_MENU;
      drawMenu();
    }
    return;
  }
}