#include <Adafruit_SSD1306.h>
#include <Adafruit_GFX.h> // Adafruit libraries 
#include "RTClib.h" // reat time library

#define OLED_WIDTH 128
#define OLED_HEIGHT 64
#define OLED_ADDR   0x3C
#define RED 0xF800

String inp;
int inp_mem;
int Centerx = 63;
int Centery = 31;
int x;
int y;
int x1;
int y1;
Adafruit_SSD1306 display(OLED_WIDTH, OLED_HEIGHT); // initializing the OLED Screen
RTC_DS1307 rtc; // Initializing the RTC Module

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

  Serial.println("Select Option.");
  Serial.println("Option 1: Digital Clock.");
  Serial.println("Option 2: Analog Clock.");

  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    Serial.flush();
    abort();
  }

  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR); // Starting up the display
  display.clearDisplay();
  display.display();
}

void loop() {
  inp = Serial.readStringUntil("\n");
  int input = inp.toInt();

  if (input == 1) {
    inp_mem = 1;
  }
  else if (input == 2) { // input memory to store user input
    inp_mem = 2;
  }

  if (inp_mem == 1) {
    DigitalClock();
  }

  else if (inp_mem == 2) { // compares user input memory and runs respective function

    AnalogClock();
  }
}

void AnalogClock() { // Analog Clock Function
  DateTime now = rtc.now(); // Calls for the RTC Module
  int h = now.hour(); // Real time Hour
  int m = now.minute(); // Real time Minutes
  int s = now.second(); // Real time Seconds

  display.setTextColor(WHITE);
  display.drawCircle(Centerx, Centery, 30, WHITE);
  display.setCursor(20, 25); // display settings to display the clock
  drawMinute(m);
  drawHour(h, m);
  drawSecond(s); // functions to draw the hours seconds and minutes
  display.display();
  display.clearDisplay();
  delay(500);
}

void DigitalClock() { // Digital Clock Function
  DateTime now = rtc.now();
  int h = now.hour();
  int m = now.minute();
  int s = now.second(); // Grabs the real time hours minutes and seconds

  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(20, 25); // decides where to print on the screen
  display.print(h);
  display.print(':');
  display.print(m);
  display.print(':');
  display.print(s);
  display.display();
  display.clearDisplay(); // displays all the real time

}

void drawMinute(int m) {
  y = (24 * cos(PI - (2 * PI) / 60 * m)) + Centery; // x-coords of the minute hand
  x = (24 * sin(PI - (2 * PI) / 60 * m)) + Centerx; // y-coords of the minute hand
  display.drawLine(Centerx, Centery, x, y, WHITE); // draws a white line starting from center to the coordinate
}

void drawHour(int h, int m) {
  y = (18 * cos(PI - (2 * PI) / 12 * h - (2 * PI) / 720 * m)) + Centery; // y-coords of the hour hand
  x = (18 * sin(PI - (2 * PI) / 12 * h - (2 * PI) / 720 * m)) + Centerx; // x-coords of the hour hand
  y1 = (18 * cos(PI - (2 * PI) / 12 * h - (2 * PI) / 720 * m)) + Centery + 1;
  x1 = (18 * sin(PI - (2 * PI) / 12 * h - (2 * PI) / 720 * m)) + Centerx + 1; // secondary coords of the hour hand
  display.drawLine(Centerx, Centery, x, y, WHITE);
  display.drawLine(Centerx + 1, Centery + 1, x1, y1, WHITE); // draws two lines with a superposition of 1 so the line appears thicker
}

void drawSecond(int s) {
  y = (24 * cos(PI - (2 * PI) / 60 * s)) + Centery; // x-coords of the second hand
  x = (24 * sin(PI - (2 * PI) / 60 * s)) + Centerx; // y-coords of the second hand
  display.drawLine(Centerx, Centery, x, y, WHITE); // draws a white line starting from center to the coordinate
}