#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <DS1307RTC.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define BUZZER_PIN 2
#define BUTTON_PIN_SET 3
#define BUTTON_PIN_HOUR 4
#define BUTTON_PIN_MIN 5
#define BUTTON_PIN_STOP 6
#define SHORT_PRESS_TIME 1000; // 500 milliseconds
#define LONG_PRESS_TIME  2000; // 3000 milliseconds

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

int alarmHour = 1;
int alarmMinute = 00;
int alarmSecond = 00;
String alarmAMPM = "AM";
bool buzzerActive = false;
bool alarmEnabled = true;

bool alarmSetMode = false;
bool hourEditMode = false;
bool minuteEditMode = false;


int lastState = LOW;  // the previous state from the input pin
int currentState;     // the current reading from the input pin
unsigned long pressedTime  = 0;
unsigned long releasedTime = 0;


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

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

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN_SET, INPUT_PULLUP);
  pinMode(BUTTON_PIN_HOUR, INPUT_PULLUP);
  pinMode(BUTTON_PIN_MIN, INPUT_PULLUP);
  pinMode(BUTTON_PIN_STOP, INPUT_PULLUP);

  delay(100);
  display.clearDisplay();
  display.setTextColor(WHITE);
}

void printDateTime(tmElements_t tm, bool showAMPM = true) {
  // Print date and time
  int hour12 = (tm.Hour % 12 == 0) ? 12 : tm.Hour % 12;
  String ampm = (tm.Hour < 12) ? "AM" : "PM";

  display.print(tm.Month);
  display.print("/");
  display.print(tm.Day);
  display.print("/");
  display.print((tmYearToCalendar(tm.Year)) % 100);
  display.print("  ");

  display.print(hour12);
  display.print(":");
  if (tm.Minute < 10) display.print("0");
  display.print(tm.Minute);
  display.print(":");
  if (tm.Second < 10) display.print("0");
  display.print(tm.Second);
  if (showAMPM) {
    display.print(" ");
    display.println(ampm);
  }
}

void printAlarmTime() {
  // Print alarm time
  display.print("Alarm Time: ");
  display.print(alarmHour);
  display.print(":");
  if (alarmMinute < 10) display.print("0");
  display.print(alarmMinute);
  display.print(" ");
  display.println(alarmAMPM);
}

void printSetAlarmTime() {
   // Print set alarm time
  display.print("Set Alarm: ");
  
  // Introduce a flag to track AM/PM change
  static bool ampmChangeDone = false;

  if (hourEditMode) {
    if (alarmHour == 12 && !ampmChangeDone) {
      if (alarmAMPM == "AM") {
        alarmAMPM = "PM";
      } else {
        alarmAMPM = "AM";
      }

      // Set the flag to indicate AM/PM change is done
      ampmChangeDone = true;
    } else if (alarmHour != 12) {
      // Reset the flag when the hour is not 12
      ampmChangeDone = false;
    }

    if (alarmHour < 10) {
      display.print(" ");
    }
    display.print(alarmHour);
    display.print(":");
  } else {
    if (alarmHour < 10) {
      display.print(" ");
    }
    display.print(alarmHour);
    display.print(":");
  }
  
  if (alarmMinute < 10) display.print("0");
  display.print(alarmMinute);
  display.print(" ");
  display.println(alarmAMPM);
}

void loop() {
  // Read current time
  tmElements_t tm;
  RTC.read(tm);

  // Display date and time
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  display.setCursor(0, 0);
  int hour12 = (tm.Hour % 12 == 0) ? 12 : tm.Hour % 12;
  String ampm = (tm.Hour < 12) ? "AM" : "PM";
  printDateTime(tm);

  display.setCursor(0, 20);
  if (alarmSetMode) {
    printSetAlarmTime();
  } else {
    printAlarmTime();
  }




  int currentState = digitalRead(BUTTON_PIN_SET);

  if (lastState == HIGH && currentState == LOW) {     // button is pressed
    pressedTime = millis();
  }  
  else if (lastState == LOW && currentState == HIGH) { // button is released
    releasedTime = millis();

    long pressDuration = releasedTime - pressedTime;

    if (pressDuration < 1000) 
      alarmSetMode = !alarmSetMode;  

    if(pressDuration > 1000)
      alarmEnabled = !alarmEnabled;
  }

  // save the last state
  lastState = currentState;
  
  if (!alarmEnabled) {
    display.setCursor(0, 50);
    display.print("Alarm Off");
  } else {
    display.setCursor(0, 50);
    display.print("Alarm On");    
  }






  // Handle alarm set mode button presses
  if (alarmSetMode) {
    if (digitalRead(BUTTON_PIN_HOUR) == LOW) {
      hourEditMode = !hourEditMode;
      if (hourEditMode) {
        alarmHour = (alarmHour + 1) % 13;
        if (alarmHour == 0) alarmHour = 1;
        delay(50);
      }
    }

    if (digitalRead(BUTTON_PIN_MIN) == LOW) {
      minuteEditMode = !minuteEditMode;
      if (minuteEditMode) {
        alarmMinute = (alarmMinute + 1) % 60;
        delay(50);  // Debounce delay
      }
    }
  }

  if (hour12 == alarmHour && tm.Minute == alarmMinute && tm.Second == alarmSecond && ampm == alarmAMPM && alarmEnabled == true) {
    if (!buzzerActive) {
      tone(BUZZER_PIN, 1000);
      buzzerActive = true;
    }
  }

  // Check if the button is pressed to stop the alarm
  if (digitalRead(BUTTON_PIN_STOP) == LOW && alarmEnabled == true) {
    // Turn off the buzzer and keep it off
    noTone(BUZZER_PIN);
    buzzerActive = false;
    delay(50);  // Debounce delay
    pinMode(BUTTON_PIN_STOP, INPUT_PULLUP);
  }

  display.display();
  delay(50);
}