#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <RTClib.h>
#include <time.h>
#include <EEPROM.h>
#include <math.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SERIAL_OPTION 0  

const int button1Pin = 2;
const int button2Pin = 50;
const int button3Pin = 40;
const int buzzerPin = 3;

int aHour;
int aMinute;
int aSecond;

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
RTC_DS1307 RTC;

const int HOUR_EEPROM_ADDRESS = 0;
const int MINUTE_EEPROM_ADDRESS = 0;
const int SECOND_EEPROM_ADDRESS = 0;

bool digitalMode = true; 
bool twedigMode = false; 
bool alarmMode = false;
int buttonState = HIGH; 
int twebutState = HIGH; 
int lastButtonState = HIGH; 

void setup() {
  Serial.begin(9600);
  Wire.begin();
  analogReference(EXTERNAL);
  pinMode(button1Pin, INPUT_PULLUP);
  pinMode(button2Pin, INPUT_PULLUP);
  pinMode(button3Pin, INPUT_PULLUP);
  pinMode(buzzerPin, OUTPUT);

  Serial.println("Digital Timer and Alarm Clock");


  RTC.begin();    
  if (! RTC.isrunning()) {
    Serial.println("RTC is NOT running!");
  RTC.adjust(DateTime(__DATE__, __TIME__));
  }

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3D)) { 
    Serial.println("SSD1306 allocation failed.");
    Serial.flush();
    while (1) delay(10);
    }

  display.display();
  delay(700);

  display.clearDisplay();
  delay(700); 
}

void loop() {
//RTC.adjust(DateTime(2023,04,22,12,36,30));  
  buttonState = digitalRead(button1Pin);
  if (lastButtonState && twebutState != buttonState) {
    if (buttonState == LOW) {
      digitalMode = true;
      twedigMode = false;
    }
  }
   lastButtonState = twebutState = buttonState;

  buttonState = digitalRead(button3Pin);
  if (lastButtonState && buttonState != twebutState) {
    if (buttonState == LOW) {
      twedigMode = true;
      digitalMode = false;
    }
  }
   lastButtonState = twebutState = buttonState;

  twebutState = digitalRead(button2Pin);
  if (twebutState && buttonState != lastButtonState) {
    if (twebutState == LOW) {
      alarmMode = true;
      twedigMode = false;
    }
  }
   lastButtonState = twebutState = buttonState;

  if (digitalMode) {
    digital();}
  if (twedigMode) {
    twedig();
  } else if (alarmMode) {
    alarm();
  }
}

void digital() {
    DateTime now = RTC.now();
    if (SERIAL_OPTION) {
    Serial.print(now.year()); Serial.print("/");
    Serial.print(now.month()); Serial.print("/");
    Serial.print(now.day()); Serial.print(" ");

    Serial.print(now.hour()); Serial.print(":");
    Serial.print(now.minute()); Serial.print(":");
    Serial.print(now.second()); Serial.print("\n");
    }
  display.clearDisplay();

  display.setTextSize(1);             
  display.setTextColor(SSD1306_WHITE);

  display.setCursor(0,5); 
  display.println("Date:");

  display.setCursor(0,15); 
  display.print(now.year()); display.print("/"); display.print(now.month()); display.print("/"); display.print(now.day());

  display.setCursor(0,25); 
  display.println("Time:");

  display.setCursor(0,35); 
  display.print(now.hour()); display.print(":"); display.print(now.minute()); display.print(":"); display.print(now.second());

  display.display();
  display.clearDisplay();
  delay(1000);
}

void twedig() {
    DateTime now = RTC.now();
    if (SERIAL_OPTION) {
    Serial.print(now.year()); Serial.print("/");
    Serial.print(now.month()); Serial.print("/");
    Serial.print(now.day()); Serial.print(" ");

    Serial.print(now.hour()); Serial.print(":");
    Serial.print(now.minute()); Serial.print(":");
    Serial.print(now.second()); Serial.print("\n");
    }
  display.clearDisplay();

  display.setTextSize(1);             
  display.setTextColor(SSD1306_WHITE);

  display.setCursor(0,15); 
  display.println("12 Hour Time:");

  display.setCursor(0,25); 
  display.print(now.hour()-12); display.print(":"); display.print(now.minute()); display.print(":"); display.print(now.second());

  display.display();
  display.clearDisplay();
  delay(1000);
}

void writeString(int address, String data) {
  for (int i = 0; i < data.length(); i++) {
    EEPROM.write(address + i, data[i]);
  }
  EEPROM.write(address + data.length(), '\0');
}

void readString(char* buffer, int length) {
  int i = 0;
  while (i < length - 1) {
    char c = Serial.read();
    if (c == '\n' || c == '\r') {
      break;
    }
    buffer[i++] = c;
    Serial.write(c);
  }
  buffer[i] = '\0';
}

void alarm() {
DateTime now = RTC.now();
  String alarmHour, alarmMinute, alarmSecond;
  display.setTextColor(WHITE);
  display.setTextSize(1);

  Serial.println("Set Hour:");
  display.clearDisplay();
  display.setCursor(0, 20);
  display.println("Set Hour:");
  display.display();
  while (!Serial.available()) {}
  alarmHour = Serial.readString();

  Serial.println("Set Minute:");
  display.clearDisplay();
  display.setCursor(0, 20);
  display.println("Set Minute:");
  display.display();
  while (!Serial.available()) {}
  alarmMinute = Serial.readString();
  
  Serial.println("Set Second:");
  display.clearDisplay();
  display.setCursor(0, 20);
  display.println("Set Second:");
  display.display();
  while (!Serial.available()) {}
  alarmSecond = Serial.readString();

  writeString(HOUR_EEPROM_ADDRESS, alarmHour);
  writeString(MINUTE_EEPROM_ADDRESS, alarmMinute);
  writeString(SECOND_EEPROM_ADDRESS, alarmSecond);

  // Display name and ID on OLED
  display.clearDisplay();
  display.setCursor(0, 20);
  display.println("Time Set:");
  display.setCursor(60, 20);
  display.println(alarmHour);
  display.setCursor(70, 20);
  display.println(":");
  display.setCursor(80, 20);
  display.println(alarmMinute);
  display.setCursor(90, 20);
  display.println(":");
  display.setCursor(100, 20);
  display.println(alarmSecond);
  display.display();
  delay(10000);
}