#include <TM1637.h>           // Include the library for the TM1637 4-digit display

int buzzer = 8; 
const int CLK = 2;            // Set the clock pin of the TM1637 to Arduino pin 2
const int DIO = 3;            // Set the data pin of the TM1637 to Arduino pin 3

const int pauseButton = 4;     // Button to pause/resume the countdown
const int set10Button = 5;     // Button to set time to 10 minutes
const int set0Button = 6;      // Button to set time to 0
const int increaseButton = 7;  // Button to increase time
const int decreaseButton = 9;  // Button to decrease time

bool isPaused = false;         // State variable to check if paused

TM1637 tm(CLK, DIO);          // Create a display object named 'tm' using the defined pins

int seconds = 600;              // Initialize a variable to keep track of the number of seconds passed
int val = -1;

void setup() {
  tm.init();                     // Initialize the display
  pinMode(buzzer, OUTPUT);        // Buzzer output
  tm.set(BRIGHT_TYPICAL);         // Set the brightness to a typical (default) level

  // Set buttons as input pullups
  pinMode(pauseButton, INPUT_PULLUP);
  pinMode(set10Button, INPUT_PULLUP);
  pinMode(set0Button, INPUT_PULLUP);
  pinMode(increaseButton, INPUT_PULLUP);
  pinMode(decreaseButton, INPUT_PULLUP);
}

void loop() {
  // --- Button handling ---
  if (digitalRead(pauseButton) == LOW) 
  {
    delay(200);  // Simple debounce
    isPaused = !isPaused; // Toggle pause/resume
  }
  
  if (digitalRead(set10Button) == LOW) {
    delay(200);
    seconds = 600;  // Set timer to 10 minutes
  }
  
  if (digitalRead(set0Button) == LOW)
   {
    delay(200);
    seconds = 0;    // Set timer to 0
   }
  
  if (digitalRead(increaseButton) == LOW)
  {
    delay(200);
    seconds = seconds +5;  // Increase timer by 1 seconds
    if (seconds > 600) seconds = 600; //Prevent the time to go above 600 seconds

  }
  
  if (digitalRead(decreaseButton) == LOW) 
  {
    delay(200);
    seconds = seconds - 5;  // Decrease timer by 1 minute
    if (seconds < 0) seconds = 0;  // Prevent negative time
  }
  
  // --- Your original countdown code ---
  if (seconds > val)
  {       
    int minutes = seconds / 60;  
    int secs = seconds % 60;     
    tm.display(0, minutes / 10); 
    tm.display(1, minutes % 10); 
    tm.display(2, secs / 10);    
    tm.display(3, secs % 10);    
    if (minutes == 10) {
      tone(buzzer, 1000, 1000);  
    }

    if (!isPaused) {
      delay(100);          // Wait for 10 seconds (your original delay)
      seconds--;             // Decrease time only if not paused
    }
  }
  else 
  {
    seconds = seconds + 600;
    delay(1000);
  }
}