#include <BluetoothSerial.h>

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.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);
  SerialBT.begin("ESP32_Device1");  // Bluetooth name
  Serial.println("Device 1 Bluetooth Started. Waiting for connection...");

  // Initialize the OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // I2C address 0x3C
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.println("Waiting for Data...");
  display.display();
}

void loop() {
  if (SerialBT.hasClient() && SerialBT.available()) {
    // Read incoming data from Device 2
    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 Device 2
    SerialBT.println("Device 1 Acknowledged: " + receivedData);
  }
  
  delay(20); // Small delay for stability
}