int IR_sensor = 11; // input from IR sensor
int shutter = 3; // led pin
int filming_led = 9;
long shutterOnInterval = 1000;
long filmPeriod = 5000;
int timerRunning = 0;
int filming = 0;
unsigned long  startTime = 0;
unsigned long  timeNow = 0;
//--------------------------------------------------------------------
void setup() {
  pinMode(IR_sensor, INPUT);
  pinMode(shutter, OUTPUT);
  pinMode (filming_led, OUTPUT);
  Serial.begin(9600);
  Serial.println("IR_sensor_V3.ino");
}
//--------------------------------------------------------------------
void loop() {
  //read the IR sensor. If HIGH, start the on/off signal
  if ((digitalRead(IR_sensor) == HIGH) && (timerRunning == 0))  {
    Serial.println("start filming ");
    startTime = millis();
    digitalWrite(shutter, HIGH);
    digitalWrite(filming_led, HIGH);
    timerRunning = 1;
    filming = 1;
   // Serial.println("1 signal and  filming started");
  }
  //stop the on/off signal after the lamponinterval. filming still running
  //timeNow = millis();
  if ((timerRunning == 1) && (millis() - startTime) >= shutterOnInterval )  {
    Serial.println("end pulse 1 ");
    digitalWrite(shutter, LOW);
    timerRunning = 2;
   // Serial.println("2 signal stopped BUT Still filming");
  }
  //if filming period is done, stop filming and send on/off signal
  // timeNow = millis();
  if (((millis() - startTime) > filmPeriod) && (filming == 1))  {
    Serial.println("stop filming ");
    digitalWrite(shutter, HIGH);
    digitalWrite(filming_led, LOW);
    filming = 0;
    timerRunning = 3;
    startTime = millis();
    //Serial.println("3 filming ended and signal to stop is started");
  }
  //stop the on/off signal after the lamponinterval and after the filmPeriod
  //timeNow = millis();
  if ((timerRunning == 3) && (millis() - startTime) >= shutterOnInterval ) {
    Serial.println("end pulse 2 ");
    digitalWrite(shutter, LOW);
    timerRunning = 0;
    //Serial.println("4 filming stopped and signal SENT");
  }
  if ((digitalRead(IR_sensor) == HIGH) && (timerRunning == 2) && (filming == 1))  {  //Extende time
    startTime = startTime + filmPeriod;
    Serial.println("extended");
  }
}