#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

// Declaration for SSD1306 display connected using I2C
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

const int stsp = A0;
const int inc = A1;
const int dec = A2;
const int set = A3;
const int buzz = 9;
const int relay = 8;

int hrs = 0;
int Min = 0;
int sec = 0;
unsigned int check_val = 50;
int add_chk = 0;
int add_hrs = 1;
int add_min = 2;
bool RUN = true;
bool min_flag = true;
bool hrs_flag = true;

int val;

void INIT()
{
  hrs = EEPROM.read(add_hrs);
  Min = EEPROM.read(add_min);
  sec = 0;
  display.clearDisplay();
  // Display Text
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(5,10);
  display.print("Start / Set Time");
  display.setTextSize(1);
  display.setCursor(20,42);
  if (hrs <= 9)
  {
    display.print('0');
  }
  display.print(hrs);
  display.print(':');
  if (Min <= 9)
  {
    display.print('0');
  }
  display.print(Min);
  display.print(':');
  if (sec <= 9)
  {
    display.print('0');
  }
  display.print(sec);
  min_flag = true;
  hrs_flag = true;
  //delay(500);
  display.display();
  //delay(2000);
  display.clearDisplay();
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
  
  // // Clear the buffer.
  display.clearDisplay();

  // Display Text
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(5,10);
  display.print("   ELECTRONIC");
  display.setTextSize(1);
  display.setCursor(20,42);
  display.print("COUNTDOWN TIMER");
  display.display();
  //delay(2000);
  display.clearDisplay();

  pinMode(stsp, INPUT_PULLUP);
  pinMode(inc, INPUT_PULLUP);
  pinMode(dec, INPUT_PULLUP);
  pinMode(set, INPUT_PULLUP);
  pinMode(buzz, OUTPUT);
  pinMode(relay, OUTPUT);
  digitalWrite(relay, LOW); 
  digitalWrite(buzz, LOW);

  if (EEPROM.read(add_chk) != check_val)
  {
    EEPROM.write(add_chk, check_val);
    EEPROM.write(add_hrs, 0);
    EEPROM.write(add_min, 1);
  }
  else
  {
    hrs = EEPROM.read(add_hrs);
    Min = EEPROM.read(add_min);
  }
  //delay(1500);
  INIT();

}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(stsp) == LOW)
  {
    Serial.println("Button OK");
    display.clearDisplay();
    delay(250);
    RUN = true;
    while (RUN)
    {
      if (digitalRead(stsp) == LOW)
      {
        delay(1000);
        if (digitalRead(stsp) == LOW)
        {
          Serial.println("Button stop");
          digitalWrite(relay, LOW); 
          display.setTextSize(1);
          display.setTextColor(WHITE);
          display.setCursor(5,10);
          display.print("  TIMER STOPPED");
          display.setTextSize(1);
          display.setCursor(5,20);
          display.print("----------------");
          display.display();
          display.clearDisplay();
          delay(2000);
          RUN = false;
          INIT();
          break;
        }
      }
      digitalWrite(relay, HIGH); 
      sec = sec - 1;
      delay(1000);
      if (sec == -1)
      {
        sec = 59;
        Min = Min - 1;
      }
      if (Min == -1)
      {
        Min = 59;
        hrs = hrs - 1;
      }
      if (hrs == -1) hrs = 0;
      display.setTextSize(1);
      display.setTextColor(WHITE);
      display.setCursor(5,11);
      display.print("****************");
      display.setTextSize(1);
      display.setCursor(20,42);
      if (hrs <= 9)
      {
        display.print('0');
      }
      display.print(hrs);
      display.print(':');
      if (Min <= 9)
      {
        display.print('0');
      }
      display.print(Min);
      display.print(':');
      if (sec <= 9)
      {
        display.print('0');
      }
      display.print(sec);
      if (hrs == 0 && Min == 0 && sec == 0)
      {
        digitalWrite(relay, LOW); 
        display.setCursor(20,42);
        RUN = false;
        for (int i = 0; i < 20; i++)
        {
          digitalWrite(buzz, HIGH);
          delay(100);
          digitalWrite(buzz, LOW);
          delay(100);
        }
        INIT();
      }
      display.display();
      display.clearDisplay();
    }
  }


  if (digitalRead(set) == LOW)
  {
    Serial.println("Button set");
    delay(500);
    while (min_flag)
    {
      display.clearDisplay();
      display.setTextSize(1);
      display.setTextColor(WHITE);
      display.setCursor(5,10);
      display.print("SET MINUTE: ");
      display.print(Min);
      
      delay(100);
      if (digitalRead(inc) == LOW)
      {
        Min = Min + 1;
        if (Min >= 60) Min = 0;
        delay(100);
      }
      if (digitalRead(dec) == LOW)
      {
        Min = Min - 1;
        if (Min <= -1) Min = 0;
        delay(100);
      }
      if (digitalRead(set) == LOW)
      {
        min_flag = false;
        delay(250);
      }
      display.display();
      display.clearDisplay();
    }
    while (hrs_flag)
    {
      display.clearDisplay();
      display.setTextSize(1);
      display.setTextColor(WHITE);
      display.setCursor(5,10);
      display.print("SET HOUR: ");
      display.print(hrs);
      delay(100);
      if (digitalRead(inc) == LOW)
      {
        hrs = hrs + 1;
        if (hrs > 23) hrs = 0;
        delay(100);
      }
      if (digitalRead(dec) == LOW)
      {
        hrs = hrs - 1;
        if (hrs <= -1) hrs = 0;
        delay(100);
      }
      if (digitalRead(set) == LOW)
      {
        hrs_flag = false;
        delay(250);
      }
      display.display();
      display.clearDisplay();
    }
    if (hrs == 0 && Min == 0)
    {
      display.clearDisplay();
      display.setTextSize(1);
      display.setTextColor(WHITE);
      display.setCursor(5,10);
      display.print("  INVAID TIME");
      display.display();
      display.clearDisplay();
      delay(2000);
    }
    else
    {
      EEPROM.write(add_hrs, hrs);
      EEPROM.write(add_min, Min);
    }
    INIT(); 
  }




}