#include <Servo.h>

// constants won't change
const int TRIG_PIN  = 6;  // Arduino pin connected to Ultrasonic Sensor's TRIG pin
const int ECHO_PIN  = 7;  // Arduino pin connected to Ultrasonic Sensor's ECHO pin
const int SERVO_PIN = 9; // Arduino pin connected to Servo Motor's pin
const int BUZZER_PIN = 3; // Arduino pin connected to Piezo Buzzer's pin
const int DISTANCE_THRESHOLD = 50; // centimeters
const int PIN_RED   = 12;
const int PIN_GREEN = 10;
const int PIN_BLUE  = 11;

Servo servo; // create servo object to control a servo

// variables will change:
float duration_us, distance_cm;
int pos = 90;

void setup() {
  Serial.begin (9600);       // initialize serial port
  pinMode(TRIG_PIN, OUTPUT); // set arduino pin to output mode
  pinMode(ECHO_PIN, INPUT);  // set arduino pin to input mode
  pinMode(BUZZER_PIN, OUTPUT); // set arduino pin to output mode
  servo.attach(SERVO_PIN);   // attaches the servo on pin 9 to the servo object
  servo.write(pos);
  pinMode(PIN_RED,   OUTPUT);
  pinMode(PIN_GREEN, OUTPUT);
  pinMode(PIN_BLUE,  OUTPUT);
}


void loop() {
  // generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin
  duration_us = pulseIn(ECHO_PIN, HIGH);
  // calculate the distance
  distance_cm = 0.017 * duration_us;

  if(distance_cm < DISTANCE_THRESHOLD){
    digitalWrite(BUZZER_PIN, HIGH); // turn on Piezo Buzzer
    // color red
    setColor(255, 0, 0);
    lookServ(); // call function lookServ()
  }
  else{
    // color green
    setColor(0, 255, 0);
    digitalWrite(BUZZER_PIN, LOW);  // turn off Piezo Buzzer
    servo.write(pos);  // servo 90 degree
  }

  // print the value to Serial Monitor
  Serial.print("distance: ");
  Serial.print(distance_cm);
  Serial.println(" cm");

  delay(500);
}

void setColor(int R, int G, int B) {
  // set the color for LED RGB
  analogWrite(PIN_RED,   R);
  analogWrite(PIN_GREEN, G);
  analogWrite(PIN_BLUE,  B);
}

void lookServ(){
  //serv look right and left then back to pos
  servo.write(30); 
  delay(700);
  servo.write(150);
  delay(700);
  servo.write(pos);
  delay(500);
}