#include <OPC.h>
#include <Arduino.h>
#include <WiFi.h>
#include <PubSubClient.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
volatile byte outputData = 0;
volatile byte inputData = 0;
Adafruit_SSD1306 display(128, 64, &Wire, -1);
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "broker.emqx.io";
const int mqtt_port = 1883;
const char* mqtt_topic_input = "esp32/inputData";
const char* mqtt_topic_output = "esp32/outputData";
WiFiClient espClient;
PubSubClient client(espClient);
OPCSerial opc;
byte dataCallback(const char *itemID, const opcOperation opcOP, const byte value) {
  if (opcOP == opc_opwrite) {
    outputData = value;
    char msg[4];
    snprintf(msg, 4, "%d", outputData);
    client.publish(mqtt_topic_output, msg);
    updateOLED();
  }
  return inputData;
}
void setup_wifi() {
  delay(10);
  //  Serial.println();
  //  Serial.print("Connecting to ");
  //  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    //    Serial.print(".");
  }
  //  Serial.println("");
  //  Serial.println("WiFi connected");
  //  Serial.println("IP address: ");
  //  Serial.println(WiFi.localIP());
}
void mqtt_callback(char* topic, byte* payload, unsigned int length) {
  //  Serial.print("Message arrived [");
  //  Serial.print(topic);
  //  Serial.print("] ");
  char message[length + 1];
  strncpy(message, (char*)payload, length);
  message[length] = '\0';
  //  Serial.println(message);
  if (strcmp(topic, mqtt_topic_input) == 0) {
    int value = atoi(message);
    if (value >= 0 && value <= 255) {
      inputData = value;
      //  Serial.print("Set inputData via MQTT: ");
      //  Serial.println(inputData);
      updateOLED();
    }
  }
}
void reconnect_mqtt() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32OPCClient")) {
      //      Serial.println("connected");
      client.subscribe(mqtt_topic_input);
    } else {
      //  Serial.print("failed, rc=");
      //  Serial.print(client.state());
      //  Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}
void updateOLED() {
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("ESP32 OPC-MQTT Monitor");
  display.drawLine(0, 12, 128, 12, SSD1306_WHITE);
  display.setCursor(0, 20);
  display.print("Input Data: ");
  display.setTextSize(2);
  display.println(inputData);
  display.setTextSize(1);
  display.setCursor(0, 45);
  display.print("Output Data: ");
  display.setTextSize(2);
  display.println(outputData);
  display.display();
}
void setupOLED() {
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.display();
  delay(2000);
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Initializing...");
  display.display();
  delay(1000);
}
void setup() {
  Serial.begin(9600);
  setupOLED();
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("Connecting WiFi");
  display.display();
  setup_wifi();
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("WiFi connected");
  display.print("IP: ");
  display.println(WiFi.localIP());
  display.display();
  delay(2000);
  client.setServer(mqtt_server, mqtt_port);
  client.setCallback(mqtt_callback);
  opc.addItem(
    "esp32.data",
    opc_readwrite,
    opc_byte,
    dataCallback
  );
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("System ready");
  display.print("MQTT: ");
  display.println(mqtt_server);
  display.display();
  delay(2000);
  updateOLED();
}
void loop() {
  if (!client.connected()) {
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0, 0);
    display.println("MQTT disconnected");
    display.print("Reconnecting...");
    display.display();
    reconnect_mqtt();
  }
  client.loop();
  opc.processOPCCommands();
}