#include "RTClib.h"
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <EEPROM.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


RTC_DS1307 rtc; //create an instant of RTC

#define button1 2
#define button2 3

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

  pinMode(button1, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(button1), timeMode, LOW);
  pinMode(button2, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(button2), alarm, LOW);

//check rtc connection
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
  }

  rtc.adjust(DateTime(F(__DATE__), 1, 1, 12, 59, 55));

  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(2);
}

void timeMode(){
  static unsigned long previousTime = 0;
  unsigned long currentTime = millis();
  if (currentTime - previousTime > 50){
    if (EEPROM.read(0) == 0){
      EEPROM.write(0,1);
    } else{
      EEPROM.write(0,0);
    }
    previousTime = currentTime;
  }
}

void alarm(){
  static unsigned long previousTime1 = 0;
  unsigned long currentTime1 = millis();
  if (currentTime1 - previousTime1 > 50){
    int hour = EEPROM.read(1);
    if (hour < 23){
      hour += 1;
      EEPROM.write(1,hour);
    } else{
      EEPROM.write(1,0);
    }
    previousTime1 = currentTime1;
  }
}


void loop () {
  if (EEPROM.read(0) == 0){
    twelveHour();
  } else{
    twentyFourHour();
  }
}

void twelveHour(){
  DateTime now = rtc.now();
  display.clearDisplay();
  display.setCursor(25, 25);
  int alarmHour = EEPROM.read(1);
  if (alarmHour > 12){
    alarmHour -= 12;
    display.setCursor(100, 25);
    display.print("PM");
    display.setCursor(25, 25);
    if (alarmHour < 10){
      display.print('0');
    }
  }
  display.print(alarmHour);
  display.print(':');
  display.print('0');
  display.print('0');
    if (now.hour() == EEPROM.read(1) && now.minute() == 0){
      display.setCursor(10, 48);
      display.write("Buzz Buzz");
    }
  display.setCursor(15, 0);
  int hour = now.hour();
  if (hour > 12)
    hour -= 12;
    if (hour < 10)
      display.print('0');
  display.print(hour);
  display.print(':');
  if (now.minute() < 10)
    display.print('0');
  display.print(now.minute());
  display.print(':');
  if (now.second() < 10)
    display.print('0');
  display.println(now.second());  
  display.display();
}

void twentyFourHour(){
  DateTime now = rtc.now();
  display.clearDisplay();
  display.setCursor(25, 25);
  display.print(EEPROM.read(1));
  display.print(':');
  display.print('0');
  display.print('0');
  if (now.hour() == EEPROM.read(1) && now.minute() == 0){
    display.setCursor(10, 48);
    display.write("Buzz Buzz");
  }
  display.setCursor(15, 0);
  if (now.hour() < 10)
    display.print('0');
  display.print(now.hour());
  display.print(':');
  if (now.minute() < 10)
    display.print('0');
  display.print(now.minute());
  display.print(':');
  if (now.second() < 10)
    display.print('0');
  display.println(now.second());  
  display.display();
}