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

LiquidCrystal_I2C lcd(0x27, 16, 2);

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'}
};

// Corrected keypad wiring: pin 1→32 through pin 8→13
byte rowPins[ROWS] = {32, 33, 25, 26};
byte colPins[COLS] = {27, 14, 12, 13};

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

enum UiMode {
  HOME_SCREEN,
  EDIT_ON_TIME,
  EDIT_OFF_TIME
};

UiMode uiMode = HOME_SCREEN;

uint16_t onMinutes = 15;
uint16_t offMinutes = 4;
String enteredValue = "";

void printLine(byte row, String text) {
  text = text.substring(0, 16);

  while (text.length() < 16) {
    text += " ";
  }

  lcd.setCursor(0, row);
  lcd.print(text);
}

void showHomeScreen() {
  char schedule[17];

  snprintf(
    schedule,
    sizeof(schedule),
    "ON:%03u OFF:%03u",
    onMinutes,
    offMinutes
  );

  printLine(0, schedule);
  printLine(1, "A=ON B=OFF");
}

void showEditScreen() {
  if (uiMode == EDIT_ON_TIME) {
    printLine(0, "SET ON TIME");
  } else {
    printLine(0, "SET OFF TIME");
  }

  String secondLine = ">";

  if (enteredValue.length() == 0) {
    secondLine += "___";
  } else {
    secondLine += enteredValue;
  }

  secondLine += " D=SAVE";
  printLine(1, secondLine);
}

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

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

  printLine(0, "INDUSTRIAL");
  printLine(1, "TIMER STARTING");
  delay(1500);

  showHomeScreen();
}

void loop() {
  char key = keypad.getKey();

  if (!key) {
    return;
  }

  Serial.print("Pressed key: ");
  Serial.println(key);

  if (uiMode == HOME_SCREEN) {
    if (key == 'A') {
      uiMode = EDIT_ON_TIME;
      enteredValue = "";
      showEditScreen();
    } else if (key == 'B') {
      uiMode = EDIT_OFF_TIME;
      enteredValue = "";
      showEditScreen();
    }

    return;
  }

  if (key >= '0' && key <= '9') {
    if (enteredValue.length() < 3) {
      enteredValue += key;
      showEditScreen();
    }
  } else if (key == '#') {
    if (enteredValue.length() > 0) {
      enteredValue.remove(enteredValue.length() - 1);
      showEditScreen();
    }
  } else if (key == 'C') {
    uiMode = HOME_SCREEN;
    enteredValue = "";
    showHomeScreen();
  } else if (key == 'D') {
    int value = enteredValue.toInt();

    if (value >= 1 && value <= 999) {
      if (uiMode == EDIT_ON_TIME) {
        onMinutes = value;
        printLine(0, "ON TIME SAVED");
      } else {
        offMinutes = value;
        printLine(0, "OFF TIME SAVED");
      }

      printLine(1, "VALUE ACCEPTED");
      delay(1200);
    } else {
      printLine(0, "INVALID VALUE");
      printLine(1, "USE 1 TO 999");
      delay(1200);
    }

    uiMode = HOME_SCREEN;
    enteredValue = "";
    showHomeScreen();
  }
}