#include <TinyGSM.h>
#include <TinyGsmClient.h>
#include <WebSocketsClient.h>

// Serial2 pins for ESP32 - GSM module communication
#define GSM_RX 16      // ESP32's TX2
#define GSM_TX 17      // ESP32's RX2

// GSM credentials
const char* apn = "YOUR_APN";  // Your cellular APN
const char* gprsUser = "";     // GPRS username (if needed)
const char* gprsPass = "";     // GPRS password (if needed)

// WebSocket server details
const char* websocket_server = "your-websocket-server.com";
const int websocket_port = 8080;
const char* websocket_path = "/";

// Initialize GSM modem
TinyGsm modem(Serial2);
TinyGsmClient gsmClient(modem);
WebSocketsClient webSocket;

// Callback function for WebSocket events
void webSocketEvent(WStype_t type, uint8_t * payload, size_t length) {
  switch(type) {
    case WStype_DISCONNECTED:
      Serial.println("WebSocket Disconnected!");
      break;
    
    case WStype_CONNECTED:
      Serial.println("WebSocket Connected!");
      webSocket.sendTXT("Hello from ESP32 + GSM!");
      break;
    
    case WStype_TEXT:
      Serial.printf("Received text: %s\n", payload);
      // Echo back the received message
      webSocket.sendTXT(payload);
      break;
    
    case WStype_ERROR:
      Serial.println("WebSocket Error!");
      break;
  }
}

void setup() {
  // Start Serial Monitor
  Serial.begin(115200);
  
  // Start Serial2 for GSM module
  Serial2.begin(9600, SERIAL_8N1, GSM_RX, GSM_TX);
  
  Serial.println("Initializing GSM module...");
  
  // Initialize GSM modem
  if (!modem.restart()) {
    Serial.println("GSM module restart failed");
    return;
  }

  Serial.println("GSM module OK");
  Serial.println("Connecting to cellular network...");

  // Connect to GPRS
  if (!modem.gprsConnect(apn, gprsUser, gprsPass)) {
    Serial.println("GPRS connection failed");
    return;
  }

  Serial.println("GPRS connected");
  Serial.print("IP Address: ");
  Serial.println(modem.localIP());

  // WebSocket server configuration
  webSocket.beginSSL(websocket_server, websocket_port, websocket_path);
  webSocket.onEvent(webSocketEvent);
  webSocket.setReconnectInterval(5000);
}

void loop() {
  // Check if GPRS is still connected
  if (!modem.isGprsConnected()) {
    Serial.println("GPRS disconnected!");
    // Try to reconnect
    modem.gprsConnect(apn, gprsUser, gprsPass);
  }

  webSocket.loop();

  // Example: Send a message every 30 seconds
  static unsigned long lastTime = 0;
  if (millis() - lastTime > 30000) {
    if (webSocket.isConnected()) {
      webSocket.sendTXT("Periodic message from ESP32 + GSM");
    }
    lastTime = millis();
  }
}

// Function to handle GSM module power cycling if needed
void resetGSM() {
  Serial.println("Resetting GSM module...");
  // Add your GSM module's reset procedure here
  // This might involve toggling a reset pin or power cycling
  delay(1000);
}