// Config LCD
#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

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

long countdownTime = 0; // Initial countdown time in seconds
bool countdownRunning = false; // Flag to track if a countdown is running
unsigned long lastUpdate = 0; // Timestamp to manage countdown updates

// LED and button pins
const int ledPin = 19;
const int button1Pin = 2;
const int button2Pin = 4;
const int button3Pin = 5;
const int button4Pin = 14; // New button pin for 1-minute countdown

void setup() {
  Serial.begin(115200);
  Serial.println("4 Push Button Countdown");

  // Initialize LED pin and button pins
  pinMode(ledPin, OUTPUT);
  pinMode(button1Pin, INPUT_PULLDOWN);
  pinMode(button2Pin, INPUT_PULLDOWN);
  pinMode(button3Pin, INPUT_PULLDOWN);
  pinMode(button4Pin, INPUT_PULLDOWN);

  // Initialize OLED display with I2C address 0x3C
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }

  display.clearDisplay();
  displayCountdown(countdownTime); // Initially display 00:00
}

void displayCountdown(long seconds) {
  int minutes = seconds / 60;
  int remainingSeconds = seconds % 60;
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 20);

  if (minutes < 10) display.print("0");
  display.print(minutes);
  display.print(":");
  if (remainingSeconds < 10) display.print("0");
  display.print(remainingSeconds);
  
  display.display();
}

void startCountdown(int minutes) {
  countdownTime = minutes * 60; // Set countdown time
  countdownRunning = true;
  lastUpdate = millis();
  digitalWrite(ledPin, HIGH); // Turn on LED as indicator
  displayCountdown(countdownTime);
  Serial.print("Countdown started for ");
  Serial.print(minutes);
  Serial.println(" minutes");
}

void startCountdownOneMinute() {
  countdownTime = 1 * 60; // Set countdown time to 1 minute
  countdownRunning = true;
  lastUpdate = millis();
  displayCountdown(countdownTime);
  Serial.println("1-minute countdown started");
}

void loop() {
  // Check if any button is pressed
  if (digitalRead(button1Pin) == HIGH) startCountdown(10);
  else if (digitalRead(button2Pin) == HIGH) startCountdown(8);
  else if (digitalRead(button3Pin) == HIGH) startCountdown(5);
  
  // If button4 (1-minute countdown) is pressed, turn on the LED
  if (digitalRead(button4Pin) == HIGH) {
    digitalWrite(ledPin, HIGH); // Keep LED on while button is pressed
    startCountdownOneMinute();   // Start or restart the 1-minute countdown
  } else if (countdownTime <= 60 && countdownRunning) {
    digitalWrite(ledPin, LOW); // Turn off LED when button is released and countdown is still active
  }

  // Countdown update every second
  if (countdownRunning && (millis() - lastUpdate >= 1000)) {
    lastUpdate = millis();
    countdownTime--;
    displayCountdown(countdownTime);

    if (countdownTime <= 0) {
      countdownRunning = false;
      digitalWrite(ledPin, LOW); // Turn off LED when countdown completes
      Serial.println("Countdown completed");
    }
  }
}