#define RED_LED     6
#define YELLOW_LED  5
#define SW          2

volatile bool interruptFlag = false;

// 0 = RED MODE, 1 = YELLOW MODE
byte mode = 0;

bool ledState = true;
byte yellowCount = 0;

unsigned long previousMillis = 0;
unsigned long lastButtonTime = 0;

// Interrupt Service Routine
void buttonISR() {
  interruptFlag = true;
}

void setup() {
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(SW, INPUT_PULLUP);

  Serial.begin(9600);

  digitalWrite(RED_LED, HIGH);
  digitalWrite(YELLOW_LED, LOW);

  attachInterrupt(
    digitalPinToInterrupt(SW),
    buttonISR,
    FALLING
  );

  previousMillis = millis();

  Serial.println("System Ready");
  Serial.println("RED LED BLINK");
}

void loop() {
  unsigned long currentMillis = millis();

  // ตรวจสอบ Interrupt จากสวิตช์
  if (interruptFlag) {
    noInterrupts();
    interruptFlag = false;
    interrupts();

    // ตรวจสอบสถานะปุ่ม และกรองการเด้ง
    if (mode == 0 &&
        digitalRead(SW) == LOW &&
        (lastButtonTime == 0 ||
         currentMillis - lastButtonTime >= 200)) {

      lastButtonTime = currentMillis;

      mode = 1;
      yellowCount = 0;
      ledState = true;

      digitalWrite(RED_LED, LOW);
      digitalWrite(YELLOW_LED, HIGH);

      previousMillis = currentMillis;

      Serial.println("IRQ DETECTED");
      Serial.println("YELLOW MODE START");
    }
  }

  // MODE 0 : ไฟแดงกระพริบ
  if (mode == 0) {

    if (currentMillis - previousMillis >= 1000) {
      previousMillis = currentMillis;

      ledState = !ledState;
      digitalWrite(RED_LED, ledState);
    }
  }

  // MODE 1 : ไฟเหลืองกระพริบ
  else if (mode == 1) {

    if (currentMillis - previousMillis >= 250) {
      previousMillis = currentMillis;

      ledState = !ledState;
      digitalWrite(YELLOW_LED, ledState);

      // ครบหนึ่งรอบเมื่อไฟเหลืองดับ
      if (ledState == LOW) {
        yellowCount++;

        Serial.print("Yellow Blink: ");
        Serial.println(yellowCount);
      }

      // กระพริบครบ 10 ครั้ง
      if (yellowCount >= 10) {

        digitalWrite(YELLOW_LED, LOW);
        digitalWrite(RED_LED, HIGH);

        mode = 0;
        ledState = true;
        previousMillis = currentMillis;

        Serial.println("YELLOW FINISHED");
        Serial.println("BACK TO RED MODE");
      }
    }
  }
}