#include <avr/sleep.h>
// #include <LowPower.h>

#define BLINK_RATE 200

const int buttonPin = 2;   // Button pin (interrupt-capable)
const int controlPin = LED_BUILTIN;  // Pin to turn off/on during sleep
volatile bool wakeUpFlag = false;

void wakeUpISR() {
  wakeUpFlag = true;  // Flag set when button pulls pin LOW
}

void blinkIfAlive() {
  static uint32_t nextBlink = 0;
  if (millis() > nextBlink) {
    digitalWrite(LED2_PIN, !digitalRead(LED2_PIN));
    nextBlink += BLINK_RATE;  // #define BLINK_RATE 200 or whatever
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(controlPin, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(buttonPin), wakeUpISR, FALLING);

  while (!Serial) {}
  Serial.println("System Ready");
}

void loop() {
  // ✅ Awake period: 5 minutes
  digitalWrite(controlPin, HIGH);  // Turn ON pin 4 when awake
  uint32_t sleepTime = millis() +  5 * 60 * 10UL;
  while (millis() < sleepTime) {
    if (wakeUpFlag) {
      Serial.println("Button pressed during awake period!");
      wakeUpFlag = false;
    }
    // Do your active tasks here
    blinkIfAlive();

    delay(10);
  }

  Serial.println("Going to sleep for 55 minutes...");

  // ❌ Sleep period: 55 minutes
  digitalWrite(controlPin, LOW);   // Turn OFF pin 4 before sleep
  for (int i = 0; i < (5 * 16) / 8; i++) {
    Serial.print('.');
    if (wakeUpFlag) {
      Serial.println("Button woke system early!");
      wakeUpFlag = false;
      break;  // Exit sleep loop immediately
    }
    set_sleep_mode(SLEEP_MODE_PWR_DOWN);
    sleep_enable();
    sleep_mode(); // now sleeping until interrupt
    sleep_disable();
    // LowPower.powerDown(SLEEP_8S, ADC_OFF, BOD_OFF);
  }

  Serial.println("Woke up from sleep!");
}