#include <BluetoothSerial.h>

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include<WiFi.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1 

BluetoothSerial SerialBT;
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void setup() {
  Serial.begin(115200);
  Serial.println(WiFi.macAddress());
  
  // Start Bluetooth with the name "ESP32_Device1"
  if (SerialBT.begin("ESP32_Device1")) {
    
    while (1); // Halt if Bluetooth fails to start
  }
  
  Serial.println("Device 1 Bluetooth Started. Waiting for connection...");
  
  // Initialize the OLED display
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // I2C address 0x3C
    
    while (1); // Halt if display initialization fails
  }
  
  display.clearDisplay(); // Clear the buffer
  display.setTextSize(1); // Set text size to 1
  display.setTextColor(WHITE); // Set text color to white
  display.setCursor(0, 0); // Set the cursor to top-left corner
  display.println("Waiting for Device 2...");
  display.display(); // Display the text
}

void loop() {
  if (SerialBT.hasClient()) {
    // Check if the client is connected
    Serial.println("Device 1: Connected to a client!");

    // Display the connection status on the OLED
    display.clearDisplay();
    display.setCursor(0, 0);
    display.println("Connected to Client");
    display.display();

    // Read incoming data from the client
    if (SerialBT.available()) {
      String receivedData = SerialBT.readString();
      Serial.println("Device 1 Received: " + receivedData);

      // Display the received data on the OLED
      display.clearDisplay();
      display.setCursor(0, 0);
      display.println("Received:");
      display.setCursor(0, 10);
      display.println(receivedData);
      display.display();

      // Send a response back to the client
      SerialBT.println("Device 1 Acknowledged: " + receivedData);
    }
  } else {
    // If no client is connected, display a message
    display.clearDisplay();
    display.setCursor(0, 0);
    display.println("Waiting for Device 2...");
    display.display();
  }
  
  delay(20); // Small delay for stability
}