// Rioke Obrimah, 4/29/2024

int greyButton = 2;
int redButton = 3;
int redLED = 12;
int greenLED = 13;
int greyButton_status = LOW;
int redButton_status = LOW;
int oldGreyStatus = LOW;
int oldRedStatus = LOW;
// Used as safeguards to prevent repetition/unwanted functions
int screenPrint = 0;
int holdBlink = 0;

void setup() {
  pinMode(greyButton, INPUT);
  pinMode(redButton, INPUT);
  pinMode(redLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  Serial.begin(9600);
}
// Green LED blink for 1 second
void greenBlink(){
  digitalWrite(greenLED, HIGH);
  delay(200);
  digitalWrite(greenLED, LOW);
  delay(200);
  digitalWrite(greenLED, HIGH);
  delay(200);
  digitalWrite(greenLED, LOW);
  delay(200);
  digitalWrite(greenLED, HIGH);
  delay(200);
  digitalWrite(greenLED, LOW);
}
// Red LED blinks for 1 second
void redBlink(){
  digitalWrite(redLED, HIGH);
  delay(200);
  digitalWrite(redLED, LOW);
  delay(200);
  digitalWrite(redLED, HIGH);
  delay(200);
  digitalWrite(redLED, LOW);
  delay(200);
  digitalWrite(redLED, HIGH);
  delay(200);
  digitalWrite(redLED, LOW);
}


void loop() {
  //Check whether each button is pressed
  greyButton_status = digitalRead(greyButton);
  delay(100);
  redButton_status = digitalRead(redButton);

// Nothing is pressed, displays "Waiting..."
if(screenPrint == 0)  {
      Serial.println("Waiting...");
      screenPrint = 1; 
  }
// Prevent light from blinking after releasing hold
if(holdBlink == 1){
      oldGreyStatus = LOW;
      oldRedStatus = LOW;
  } 
  
  // If button is pressed, old status of button is HIGH
  if(greyButton_status == HIGH){
    oldGreyStatus = HIGH;
  } 
  if(redButton_status == HIGH){
    oldRedStatus = HIGH;
  } 

  // After press and hold, safeguard released once both buttons are unpressed
  if (greyButton_status == LOW && redButton_status == LOW && holdBlink == 1){
    holdBlink = 0;
    screenPrint = 0;
  }

   // Button A is pressed, green LED blinks, displays "Vending soda"
  else if(oldGreyStatus == HIGH && redButton_status == LOW && greyButton_status == LOW && holdBlink == 0){
    Serial.println("Vending soda");
      greenBlink();
      oldGreyStatus = LOW;
      oldRedStatus = LOW;
      screenPrint = 0;
  } // Button B is pressed, green LED blinks, displays "Vending water"
  else if(oldRedStatus == HIGH && greyButton_status == LOW && redButton_status == LOW && holdBlink == 0){
    Serial.println("Vending water");
      greenBlink();
      oldRedStatus = LOW;
      oldGreyStatus = LOW;
      screenPrint = 0;
  }  // Both buttons are pressed, red LED blinks, displays "Product not available"
  else if(oldRedStatus == HIGH && oldGreyStatus == HIGH && greyButton_status == LOW && redButton_status == LOW){
    Serial.println("Product not available");
      redBlink();
      oldGreyStatus = LOW;
      oldRedStatus = LOW;
      screenPrint = 0;
  } // One button is held, other is pressed, red LED blinks, displays "Product not available"
  else if(redButton_status == HIGH && oldGreyStatus == HIGH && greyButton_status == LOW){
      Serial.println("Product not available");
      redBlink();
      oldGreyStatus = LOW;
      oldRedStatus = LOW;
      holdBlink = 1;
      
  } else if(greyButton_status == HIGH && oldRedStatus == HIGH && redButton_status == LOW){
      Serial.println("Product not available");
      redBlink();
      oldRedStatus = LOW;
      oldGreyStatus = LOW;
      holdBlink = 1;
      
  } 
}