#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <TM1637.h>

// constants won't change. They're used here to set pin numbers:
const int buttonPin = 5;  // the number of the pushbutton pin
const int CLK = 3;
const int DIO = 2;

// variables will change:
int buttonState = 0;  // variable for reading the pushbutton status

LiquidCrystal_I2C lcd(0x27,16,2);

TM1637 tm(CLK, DIO);

void setup() {
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);
  Serial.begin(9600);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0,0); // set cursor to 1 symbol of 1 line
  lcd.print("Arduino Lessons:");

  lcd.setCursor(0,1); // set cursor to 1 symbol of 2 line
  lcd.print("www.andjey.info"); 

  tm.init();
  tm.set(7);
}

void loop() {
  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed. If it is, the buttonState is HIGH:
  if (buttonState == HIGH) {
    //trigger launch
    lcd.clear();
    lcd.setCursor(0,0); // set cursor to 1 symbol of 1 line
    lcd.print("Launching");
    countdown();
  }
}

void countdown() {
  int countdownlength = 5;

  while(countdownlength > 0)
  {
    tm.display(0, countdownlength);
    delay(1000);
    countdownlength--;
  }

  timer();
}

void timer() {
  int timer = 0;

  while(true)
  {
    tm.display(3, timer % 10);
    tm.display(2, timer / 10 % 10);
    tm.display(1, timer / 100 % 10);
    tm.display(0, timer / 1000 % 10);
    lcd.setCursor(0,0); // set cursor to 1 symbol of 1 line
    lcd.print("Launched........");
    delay(1000);
    timer++;
  }
}