// PROJECT 3 Interactive Traffic Light
int carRed = 12; //configure traffic light
int carYellow = 11;
int carGreen = 10;
int button = 9; //pin of button
int pedRed = 8; //configure light for pedestrians
int pedGreen = 7;
int crossTime = 5000; //time for pedestrians to pass unsigned
long changeTime = 0; //time that the button is pressed
void setup() {
  //configure all LEDs as output
  pinMode(carRed, OUTPUT);
  pinMode(carYellow, OUTPUT);
  pinMode(carGreen, OUTPUT);
  pinMode(pedRed, OUTPUT);
  pinMode(pedGreen, OUTPUT);
  pinMode(button, INPUT); //configure button as input
  digitalWrite(carGreen, HIGH); //initialize green traffic
  digitalWrite(pedRed, LOW); //initialize red pedestrian light off 
}
void loop() {
  int state = digitalRead(button);
  // test if the button is pressed and if 5 seconds have passed after it is pressed
  if (state == HIGH && (millis() - changeTime) > 5000) {
    //carry out the function of changing LED
    changeLights();
  }
}
void changeLights() {
  digitalWrite(carGreen, LOW); //green traffic light off
  digitalWrite(carYellow, HIGH); //yellow traffic light on
  delay(2000); //wait for 2 secs

  digitalWrite(carYellow, LOW); // yellow traffic light off
  digitalWrite(carRed, HIGH); //red traffic light on
  delay(1000); // wait for 1 sec for safety reason

  digitalWrite(pedRed, LOW); //red pedestrian light off
  digitalWrite(pedGreen, HIGH); //light pedestrian light on
  delay(crossTime); // time for crossing street

  //blink green pedestrian light to notify pedestrians to pass soon
  for (int x = 0; x < 10; x++) {
    digitalWrite(pedGreen, HIGH);
    delay(250);
    digitalWrite(pedGreen, LOW);
    delay(250);
  }
  digitalWrite(pedRed, HIGH); //red pedestrian light on
  delay(500);
  digitalWrite(carRed, LOW); //red traffic light off
  digitalWrite(carYellow, HIGH); //yellow traffic light on
  delay(1000);
  digitalWrite(carYellow, LOW); //yellow traffic light off
  digitalWrite(carGreen, HIGH); //green traffic light on
  changeTime = millis(); // record the duration since last
  //back to the loop of main code
}