#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display settings
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Define button pins
#define BUTTON_UP 2
#define BUTTON_DOWN 3
#define BUTTON_NEXT 4
#define BUTTON_MENU 5

// Debounce variables
unsigned long lastDebounceTimeUp = 0;
unsigned long lastDebounceTimeDown = 0;
unsigned long lastDebounceTimeNext = 0;
unsigned long lastDebounceTimeMenu = 0;
unsigned long debounceDelay = 0;

int buttonStateUp = LOW;
int lastButtonStateUp = LOW;
int buttonStateDown = LOW;
int lastButtonStateDown = LOW;
int buttonStateNext = LOW;
int lastButtonStateNext = LOW;
int buttonStateMenu = LOW;
int lastButtonStateMenu = LOW;

enum MenuState {CLOCK, MAIN_MENU, SET_TIME_MINUTES, SET_TIME_HOURS, SET_FORMAT, SET_DISPLAY};
MenuState menuState = CLOCK;

bool is12HourFormat = true;
bool isInverseDisplay = false;

int hours = 12;
int minutes = 0;
int seconds = 0;
unsigned long lastMillis = 0;

// Menu navigation variables
int menuSelection = 0;  // Tracks the current menu selection
const int mainMenuOptions = 3;

void setup() {
  Serial.begin(9600);

  // Initialize the OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.clearDisplay();
  display.display();

  // Initialize buttons
  pinMode(BUTTON_UP, INPUT_PULLUP);
  pinMode(BUTTON_DOWN, INPUT_PULLUP);
  pinMode(BUTTON_NEXT, INPUT_PULLUP);
  pinMode(BUTTON_MENU, INPUT_PULLUP);

  // Display initial time
  updateDisplay();
}

void loop() {
  // Read the state of the buttons
  int readingUp = digitalRead(BUTTON_UP);
  int readingDown = digitalRead(BUTTON_DOWN);
  int readingNext = digitalRead(BUTTON_NEXT);
  int readingMenu = digitalRead(BUTTON_MENU);

  // Debounce buttons
  if (readingUp != lastButtonStateUp) {
    lastDebounceTimeUp = millis();
  }
  if (readingDown != lastButtonStateDown) {
    lastDebounceTimeDown = millis();
  }
  if (readingNext != lastButtonStateNext) {
    lastDebounceTimeNext = millis();
  }
  if (readingMenu != lastButtonStateMenu) {
    lastDebounceTimeMenu = millis();
  }

  if ((millis() - lastDebounceTimeUp) > debounceDelay) {
    if (readingUp != buttonStateUp) {
      buttonStateUp = readingUp;
      if (buttonStateUp == LOW) {
        handleButtonUp();
      }
    }
  }
  if ((millis() - lastDebounceTimeDown) > debounceDelay) {
    if (readingDown != buttonStateDown) {
      buttonStateDown = readingDown;
      if (buttonStateDown == LOW) {
        handleButtonDown();
      }
    }
  }
  if ((millis() - lastDebounceTimeNext) > debounceDelay) {
    if (readingNext != buttonStateNext) {
      buttonStateNext = readingNext;
      if (buttonStateNext == LOW) {
        handleButtonNext();
      }
    }
  }
  if ((millis() - lastDebounceTimeMenu) > debounceDelay) {
    if (readingMenu != buttonStateMenu) {
      buttonStateMenu = readingMenu;
      if (buttonStateMenu == LOW) {
        handleButtonMenu();
      }
    }
  }

  lastButtonStateUp = readingUp;
  lastButtonStateDown = readingDown;
  lastButtonStateNext = readingNext;
  lastButtonStateMenu = readingMenu;

  // Update the internal clock
  updateClock();

  // Display the current time or menu
  if (menuState == CLOCK) {
    displayTime();
  } else {
    displayMenu();
  }

  delay(10);
}

void updateClock() {
  unsigned long currentMillis = millis();
  if (currentMillis - lastMillis >= 1000) {
    lastMillis = currentMillis;
    seconds++;
    if (seconds >= 60) {
      seconds = 0;
      minutes++;
      if (minutes >= 60) {
        minutes = 0;
        hours++;
        if (is12HourFormat && hours > 12) hours = 1;
        if (!is12HourFormat && hours >= 24) hours = 0;
      }
    }
    if (menuState == CLOCK) {
      updateDisplay();
    }
  }
}

void handleButtonUp() {
  if (menuState == MAIN_MENU) {
    menuSelection = (menuSelection - 1 + mainMenuOptions) % mainMenuOptions;
  } else if (menuState == SET_TIME_MINUTES) {
    minutes++;
    if (minutes >= 60) {
      minutes = 0;
    }
  } else if (menuState == SET_TIME_HOURS) {
    hours++;
    if (is12HourFormat && hours > 12) hours = 1;
    if (!is12HourFormat && hours >= 24) hours = 0;
  } else if (menuState == SET_FORMAT) {
    is12HourFormat = !is12HourFormat;
  } else if (menuState == SET_DISPLAY) {
    isInverseDisplay = !isInverseDisplay;
    display.invertDisplay(isInverseDisplay);
  }
  updateDisplay();
}

void handleButtonDown() {
  if (menuState == MAIN_MENU) {
    menuSelection = (menuSelection + 1) % mainMenuOptions;
  } else if (menuState == SET_TIME_MINUTES) {
    minutes--;
    if (minutes < 0) {
      minutes = 59;
    }
  } else if (menuState == SET_TIME_HOURS) {
    hours--;
    if (is12HourFormat && hours < 1) hours = 12;
    if (!is12HourFormat && hours < 0) hours = 23;
  }
  updateDisplay();
}

void handleButtonNext() {
  if (menuState == MAIN_MENU) {
    switch (menuSelection) {
      case 0:
        menuState = SET_TIME_MINUTES;
        break;
      case 1:
        menuState = SET_FORMAT;
        break;
      case 2:
        menuState = SET_DISPLAY;
        break;
    }
  } else if (menuState == SET_TIME_MINUTES) {
    menuState = SET_TIME_HOURS;
  } else if (menuState == SET_TIME_HOURS) {
    menuState = MAIN_MENU;
  } else if (menuState == SET_FORMAT || menuState == SET_DISPLAY) {
    menuState = MAIN_MENU;
  }
  updateDisplay();
}

void handleButtonMenu() {
  if (menuState == CLOCK) {
    menuState = MAIN_MENU;
  } else {
    menuState = CLOCK;
  }
  updateDisplay();
}

void displayTime() {
  display.clearDisplay();
  display.setTextSize(2.5);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  if (is12HourFormat) {
    int displayHour = hours % 12;
    if (displayHour == 0) displayHour = 12;
    display.print(displayHour);
    display.print(':');
    if (minutes < 10) display.print('0');
    display.print(minutes);
    display.print(hours < 12 ? " AM" : " PM");
  } else {
    display.print(hours);
    display.print(':');
    if (minutes < 10) display.print('0');
    display.print(minutes);
  }
  display.display();
}

void displayMenu() {
  display.clearDisplay();
  display.setTextSize(1.8);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);

  if (menuState == MAIN_MENU) {
    displayMenuOption("Set Time", 0);
    displayMenuOption("Set Format", 1);
    displayMenuOption("Set Display", 2);
  } else if (menuState == SET_TIME_MINUTES) {
    display.println("Set Minutes");
    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print(minutes);
  } else if (menuState == SET_TIME_HOURS) {
    display.println("Set Hours");
    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print(hours);
  } else if (menuState == SET_FORMAT) {
    display.println("Set Format");
    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print(is12HourFormat ? "12H" : "24H");
  } else if (menuState == SET_DISPLAY) {
    display.println("Set Display");
    display.setTextSize(2);
    display.setCursor(0, 30);
    display.print(isInverseDisplay ? "Inverse" : "Normal");
  }
  display.display();
}

void displayMenuOption(const char* option, int index) {
  if (index == menuSelection) {
    display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Invert text color
  } else {
    display.setTextColor(SSD1306_WHITE);
  }
  display.setTextSize(1);
  display.setCursor(0, 20 + (index * 10));
  display.println(option);
  display.setTextColor(SSD1306_WHITE); // Reset to default
}

void updateDisplay() {
  if (menuState == CLOCK) {
    displayTime();
  } else {
    displayMenu();
  }
}