// Fnu Shoaib Ahmed, 652420658, fahme8
// Muhammad Taha, 671153042, mtaha6s
// Lab 7 - Communication of Arduinos

// Description - This code enables two Arduino devices to communicate via a button press,
//               toggling an LED on the other Arduino while displaying status updates on an LCD for debugging.

// Assumptions - Both Arduinos share a common ground, and the button is correctly debounced using millis() to prevent unintended multiple triggers.

// References - I used the prelab links to connect the Arduinos together.

#include <LiquidCrystal.h>

// Initialize the library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

const int buttonPin = 7;         // Pin for the button
const int ledPin = 13;           // Pin for the LED
bool ledState = LOW;             // LED state
int buttonState = 0;             // Current button state
int lastButtonState = 0;         // Previous button state
unsigned long lastDebounceTime = 0;  // Last time the button state changed
const unsigned long debounceDelay = 50;  // Debounce delay time

void setup() {
  Serial.begin(9600);             // Start serial communication
  lcd.begin(16, 2);               // Initialize the LCD
  lcd.print("Ready");             // Display initial message
  pinMode(ledPin, OUTPUT);        // Set LED pin as output
  pinMode(buttonPin, INPUT);      // Set button pin as input
}

void loop() {
  // Get the current time
  unsigned long currentMillis = millis();
  
  // Read the current state of the button
  int reading = digitalRead(buttonPin);

  // Check if the button state has changed (i.e., button is pressed or released)
  if (reading != lastButtonState) {
    lastDebounceTime = currentMillis;  // Reset the debounce timer
  }

  // If enough time has passed since the last state change, proceed
  if ((currentMillis - lastDebounceTime) > debounceDelay) {
    // Check if the button state has changed
    if (reading != buttonState) {
      buttonState = reading;

      // Only act if the button is pressed
      if (buttonState == HIGH) {
        lcd.clear();
        lcd.print("Signal Sent!");
        Serial.write("Button Pressed!");
      }
    }
  }

  // Check for incoming data from the other Arduino
  if (Serial.available() > 0) {
    String data = Serial.readStringUntil('\n');  // Read the incoming data
    if (data == "Button Pressed!") {
      lcd.clear();
      lcd.print("Signal Received!");
      ledState = !ledState;              // Toggle LED state
      digitalWrite(ledPin, ledState);    // Update LED based on received state
    }
  }

  // Update the lastButtonState
  lastButtonState = reading;
}