#include <WiFi.h>
#include <PubSubClient.h>

#define GLUCOSE_SENSOR_PIN 34  // Analog pin for glucose sensor

// WiFi credentials
const char* ssid = "Wokwi-GUEST";
const char* password = "";


// HiveMQ Cloud MQTT Broker details (secure connection)
const char* mqtt_server = "9ac40e0208a5481d9b58a4b8aad9004e.s1.eu.hivemq.cloud";
const int mqtt_port = 8883;
const char* topic = "iot/glucose";

// HiveMQ Cloud credentials
const char* mqtt_username = "hivemq.webclient.1744651559796"; 
const char* mqtt_password = "WA!&rhH2Pa%Z.f09T7dy";

WiFiClient espClient;             // Insecure WiFi client
PubSubClient client(espClient);   // MQTT client using the insecure client

// Connect to WiFi
void setup_wifi() {
  delay(10);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  
  Serial.println("\nWiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

// Callback for receiving MQTT messages (if subscribed)
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (unsigned int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

// Reconnect to MQTT broker if connection is lost
void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    // Attempt to connect using the provided MQTT credentials (if any)
    if (client.connect(clientId.c_str(), mqtt_username, mqtt_password)) {
      Serial.println(" connected");
      // Resubscribe to topic(s) if needed
      client.subscribe(topic);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 3 seconds");
      delay(3000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  setup_wifi();
  
  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(callback);
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();
  
  // Simulate reading the glucose sensor and create JSON payload
  int glucoseLevel = analogRead(GLUCOSE_SENSOR_PIN);
  String payload = "{\"glucoseLevel\": " + String(glucoseLevel) + "}";
  
  // Publish the JSON payload to the MQTT topic
  client.publish(topic, payload.c_str());
  
  Serial.print("Published: ");
  Serial.println(payload);
  
  delay(2000);  // Wait 2 seconds between readings
}