/*
  Forum: https://forum.arduino.cc/t/help-beginner-with-led-flash-for-specified-time/1337748
  Wokwi: https://wokwi.com/projects/418893876002893825

  2025/01/01
  Solution by alto777
 
  
*/

const byte buttonPin = 2;
const byte ledPin = 5;
boolean flashing = false;
byte currentButtonState = HIGH;
byte previousButtonState = HIGH;
unsigned long currentTime;
unsigned long onoffStarted;

unsigned long flashPeriod = 777;        // half-blink period
unsigned long howLongToFlash = 13000;   // shut off after a time (13 seconds here for testing)

void setup()
{
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
}

void loop()
{
  static unsigned long lastTurnedOn;
  static unsigned long lastButtonTime;    // for debouncing

  if (flashing)
  {
    currentTime = millis();
    if (currentTime - onoffStarted > flashPeriod)  // if the flash period ended ?
    {
      digitalWrite(ledPin, digitalRead(ledPin) == LOW ? HIGH : LOW);  // flip the state of the LED
      onoffStarted = currentTime;                  // save the time when it occured
    }
  }

  if (flashing && millis() - lastTurnedOn > howLongToFlash) {
    flashing = false;
    digitalWrite(ledPin, LOW);
  }

  if (millis() - lastButtonTime < 30) return;          // we done. too soon to look at the button again.

  currentButtonState = digitalRead(buttonPin);
  if (currentButtonState != previousButtonState)       // buttonstate has changed
  {
    previousButtonState = currentButtonState;          // save the button state for the next check
    lastButtonTime = millis();                         // and don't look until the debounce period is elapsed...

    if (currentButtonState == LOW) {                   // Change the flash state only if the change was from HIGH to LOW
      flashing = !flashing;
      if (!flashing) {                                 // We only need to do this once when going to "not flashing"
        digitalWrite(ledPin, LOW);                     // force the LED off if not flashing
      }
      else lastTurnedOn = millis();
    }
  }
}