#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1    // Reset pin # (or -1 if sharing Arduino reset pin)

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

unsigned long countdownTime = 0; // Initial countdown time in milliseconds
unsigned long previousMillis = 0;
bool countdownActive = false;

const int buzzerPin = 9;
const int addButton5Min = 2;
const int addButton15Min = 3;
const int addButton30Min = 4;
const int startButtonPin = 5;

void setup() {
  Serial.begin(9600);

  pinMode(buzzerPin, OUTPUT);
  pinMode(addButton5Min, INPUT_PULLUP);
  pinMode(addButton15Min, INPUT_PULLUP);
  pinMode(addButton30Min, INPUT_PULLUP);
  pinMode(startButtonPin, INPUT_PULLUP);

  // Initialize the display with the I2C addr 0x3C (for the 128x64)
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.display();
  delay(2000); // Pause for 2 seconds

  display.clearDisplay();
  display.setTextSize(1); // Set text size to 1 for smaller font
  display.setTextColor(SSD1306_WHITE);
}

void loop() {
  if (digitalRead(addButton5Min) == LOW) {
    countdownTime += 5 * 60 * 1000; // Add 5 minutes (300000 milliseconds)
    delay(200); // Debounce delay
  }
  if (digitalRead(addButton15Min) == LOW) {
    countdownTime += 15 * 60 * 1000; // Add 15 minutes (900000 milliseconds)
    delay(200); // Debounce delay
  }
  if (digitalRead(addButton30Min) == LOW) {
    countdownTime += 30 * 60 * 1000; // Add 30 minutes (1800000 milliseconds)
    delay(200); // Debounce delay
  }
  if (digitalRead(startButtonPin) == LOW && countdownTime > 0) {
    countdownActive = true;
    delay(200); // Debounce delay
  }

  if (countdownActive) {
    unsigned long currentMillis = millis();
    if (currentMillis - previousMillis >= 1000) { // Update every second
      previousMillis = currentMillis;
      countdownTime -= 1000;

      if (countdownTime <= 3 * 60 * 1000 && countdownTime > (3 * 60 * 1000 - 1000)) {
        tone(buzzerPin, 1000, 200); // Beep for 200 milliseconds when 3 minutes left
      }

      if (countdownTime == 0) {
        for (int i = 0; i < 3; i++) {
          tone(buzzerPin, 1000, 1000); // Beep for 1 second
          delay(1000); // Wait for 1 second
        }
        countdownActive = false; // Stop countdown when it reaches zero
      }
    }
  }

  // Update the display
  int hours = (countdownTime / 1000) / 3600;
  int minutes = ((countdownTime / 1000) % 3600) / 60;
  int seconds = (countdownTime / 1000) % 60;

  display.clearDisplay();
  char timeString[9];
  sprintf(timeString, "%02d:%02d:%02d", hours, minutes, seconds);
  int16_t x1, y1;
  uint16_t w, h;
  display.getTextBounds(timeString, 0, 0, &x1, &y1, &w, &h);
  display.setCursor((SCREEN_WIDTH - w) / 2, (SCREEN_HEIGHT - h) / 2);
  display.print(timeString);
  display.display();
}