#include "RTClib.h"
#include "U8glib.h"
#include <Wire.h>
#include <Adafruit_SSD1306.h>

RTC_DS1307 rtc; // create an instance of the Real Time Clock
Adafruit_SSD1306 display = Adafruit_SSD1306(128, 64, &Wire); // create an instance of the OLED display 

DateTime now = rtc.now(); //get the current time 

int clockCenterX=32;
int clockCenterY=32;
int modeToggle = 0;
boolean stateStopwatch;

unsigned long startMillis;
unsigned long currentMillis;
unsigned long elapsedMillis;

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

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

  attachInterrupt(1, modeChange, RISING);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Address 0x3C for 128x32
  display.display();

  // Clear the buffer.
  display.clearDisplay();
  display.display();
}

void modeChange(){
  static unsigned long last_interrupt_time = 0;
  unsigned long interrupt_time = millis();
  // If interrupts come faster than 200ms, assume it's a bounce and ignore
  if (interrupt_time - last_interrupt_time > 200) 
  {
    if (modeToggle != 1) {
      modeToggle = 1;
      stateStopwatch = true;
      startMillis = millis();
    } else if (modeToggle == 1 && stateStopwatch == false) {
      modeToggle = 0;
    } else if (modeToggle == 1 && stateStopwatch == true) {
      stateStopwatch = false;
    } 
  }
  last_interrupt_time = interrupt_time;
}

void drawDigital() {
  String timeStr;
  if (now.minute() >= 10)
    timeStr = String(now.hour()) + ":" + String(now.minute());
  else
    timeStr = String(now.hour()) + ":0" + String(now.minute());
  // text display tests
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(67,25);
  display.print(timeStr);
  display.setCursor(0,0);
}

void drawMark(int h)
{
  float x1, y1, x2, y2;
  
  h=h*30;
  h=h+270;
  
  x1=29*cos(h*0.0175);
  y1=29*sin(h*0.0175);
  x2=26*cos(h*0.0175);
  y2=26*sin(h*0.0175);
  
  display.drawLine(x1+clockCenterX, y1+clockCenterY, x2+clockCenterX, y2+clockCenterY, SSD1306_WHITE);
}

void drawMin(int m)
{
  float x1, y1, x2, y2, x3, y3, x4, y4;

  m=m*6;
  m=m+270;
  
  x1=25*cos(m*0.0175);
  y1=25*sin(m*0.0175);
  x2=3*cos(m*0.0175);
  y2=3*sin(m*0.0175);
  x3=10*cos((m+8)*0.0175);
  y3=10*sin((m+8)*0.0175);
  x4=10*cos((m-8)*0.0175);
  y4=10*sin((m-8)*0.0175);
  
  display.drawLine(x1+clockCenterX, y1+clockCenterY, x3+clockCenterX, y3+clockCenterY, SSD1306_WHITE);
  display.drawLine(x3+clockCenterX, y3+clockCenterY, x2+clockCenterX, y2+clockCenterY, SSD1306_WHITE);
  display.drawLine(x2+clockCenterX, y2+clockCenterY, x4+clockCenterX, y4+clockCenterY, SSD1306_WHITE);
  display.drawLine(x4+clockCenterX, y4+clockCenterY, x1+clockCenterX, y1+clockCenterY, SSD1306_WHITE);
}

void drawHour(int h, int m)
{
  float x1, y1, x2, y2, x3, y3, x4, y4;

  h=(h*30)+(m/2);
  h=h+270;
  
  x1=20*cos(h*0.0175);
  y1=20*sin(h*0.0175);
  x2=3*cos(h*0.0175);
  y2=3*sin(h*0.0175);
  x3=8*cos((h+12)*0.0175);
  y3=8*sin((h+12)*0.0175);
  x4=8*cos((h-12)*0.0175);
  y4=8*sin((h-12)*0.0175);
  
  display.drawLine(x1+clockCenterX, y1+clockCenterY, x3+clockCenterX, y3+clockCenterY, SSD1306_WHITE);
  display.drawLine(x3+clockCenterX, y3+clockCenterY, x2+clockCenterX, y2+clockCenterY, SSD1306_WHITE);
  display.drawLine(x2+clockCenterX, y2+clockCenterY, x4+clockCenterX, y4+clockCenterY, SSD1306_WHITE);
  display.drawLine(x4+clockCenterX, y4+clockCenterY, x1+clockCenterX, y1+clockCenterY, SSD1306_WHITE);
}

void drawClockFace() {
  // Draw Clockface
  for (int i=0; i<2; i++)
  {
    display.drawCircle(clockCenterX, clockCenterY, 31-i, SSD1306_WHITE);
  }
  for (int i=0; i<3; i++)
  {
    display.drawCircle(clockCenterX, clockCenterY, i, SSD1306_WHITE);
  }
  
  // Draw a small mark for every hour
  for (int i=0; i<12; i++)
  {
    drawMark(i);
  }  
}

void drawAnalog() {
  drawClockFace();
  drawMin(now.minute());
  drawHour(now.hour(), now.minute());
}

void drawStopwatch(){
    // text display tests
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(10,24);
  
  if (stateStopwatch) {
    //elapsedMillis = getStopwatch();

    currentMillis = millis();
    elapsedMillis = (currentMillis - startMillis);
    unsigned long durMS = (elapsedMillis%1000);       //Milliseconds
    unsigned long durSS = (elapsedMillis/1000)%60;    //Seconds
    unsigned long durMM = (elapsedMillis/(60000))%60; //Minutes
    unsigned long durHH = (elapsedMillis/(3600000)%24);  //Hours
    
    String timeStr = String(durHH) + ":" + String(durMM) + ":" + String(durSS) + ":" + String(durMS);
    display.print(timeStr);
  } else {
    unsigned long durMS = (elapsedMillis%1000);       //Milliseconds
    unsigned long durSS = (elapsedMillis/1000)%60;    //Seconds
    unsigned long durMM = (elapsedMillis/(60000))%60; //Minutes
    unsigned long durHH = (elapsedMillis/(3600000)%24);  //Hours

    String timeStr = String(durHH) + ":" + String(durMM) + ":" + String(durSS) + ":" + String(durMS);
      display.print(timeStr);
  }

  display.setCursor(0,0);
}

void loop() {
  display.clearDisplay();
  if (modeToggle == 0) {

    now = rtc.now();
    drawDigital();
    drawAnalog();

  } else if (modeToggle == 1) {
    drawStopwatch();
  }
  display.display();
}

/*
Continuing from Pass Plus Task 1 for designing digital clock with few features. Connect 
to a push button. You can use the hardware/timer interrupt to detect the button if needed. If the 
button is pressed, it will convert to a stopwatch or back to be digital clock. While as stopwatch, 
the same button is used to start/stop the stopwatch (Require demonstration)
*/