#include <Servo.h>

//Constants
const int  Sens1 = 2;       //Arrival detecting IR sensor on pin 2
const int Sens2 = 4;        // Gate exit IR sensor on pin 4
const int OBsensor = 7;     // Obstruction sensor on pin 7

const int TrainLEDG = 12;   // Traffic and train directing LEDS
const int TrainLEDR = 13;
const int TrafficLEDG = 5;
const int TrafficLEDR = 6;

Servo gateXing;                // Declare servo as gate mechanism

// Variables
int OBsensorState = 0;

int Sens1State = 0;         // current state of the IR sensor
int lastSens1State = 0;     // previous state of the IR sensor
                            // NOTE: These variables are necessary, in addition to the constant IR sensor declaration.
int Sens2State = 0;
int lastSens2State = 0;

void setup() {

  pinMode(Sens1, INPUT);       // IR sensors used as input
  pinMode(Sens2, INPUT);
  pinMode (OBsensor, INPUT);   // Obstruction Sensor
  pinMode(9, OUTPUT);          // Buzzer

  pinMode(TrafficLEDG, OUTPUT);
  pinMode(TrafficLEDR, OUTPUT);
  pinMode(TrainLEDG, OUTPUT);
  pinMode(TrainLEDR, OUTPUT);      //LEDs for traffic control

  gateXing.attach(10);          // servo on digital pin 10
}


void loop() {

  // Obstruction sensor code (first because highest priority)
  OBsensorState = digitalRead (OBsensor);

  if (OBsensorState == HIGH){
  digitalWrite(TrainLEDR, HIGH);
  digitalWrite(TrainLEDG, LOW);
  digitalWrite (TrafficLEDR, HIGH);
  digitalWrite (TrafficLEDG, LOW);
  gateXing.write(0);
}
  else{

   digitalWrite (TrainLEDR, LOW);

  // read the IR input pin:
  Sens1State = digitalRead(Sens1);

  Sens2State = digitalRead (Sens2);

//Arrival Proximity Sensor code

  digitalWrite(TrainLEDG, HIGH);

  if (Sens1State != lastSens1State) {          // compare the sensor state to its previous state, used for edge detection


    if (Sens1State == HIGH) {
      gateXing.write(0);         // gate closes (0 degree angle- 3 o'clock position
      digitalWrite(9, HIGH);
      digitalWrite(TrafficLEDR, HIGH);
      digitalWrite(TrafficLEDG, LOW);
    }

  }

  lastSens1State = Sens1State;      // current state (ON or OFF) is assigned as the sensor's comparator state for next loop cycle.

//Exit Crossing Sensor code

  if (Sens2State != lastSens2State) {

     if (Sens2State % 1 == 0)
     {
     gateXing.write(90);      // gate is up (90 degree angle)
     digitalWrite (9, LOW);
     digitalWrite(TrafficLEDR, LOW);
      digitalWrite(TrafficLEDG, HIGH);
     delay(700);

         }
  }
  lastSens2State = Sens2State;

  }
}