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

const char* ssid = "New Boys Hostel";
const char* password = "nithostel%boys";
const char* mqtt_server = "broker.hivemq.com";
const char* topic_brake = "train/command/brake";
const char* topic_obstacle = "train/sensor/obstacle";

const int stepPin = 17;
const int dirPin = 16;
const int enablePin = 19;

const int trigPin = 5;
const int echoPin = 18;

long duration;
int distance;

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  Serial.begin(115200);

  pinMode(stepPin, OUTPUT);
  pinMode(dirPin, OUTPUT);
  pinMode(enablePin, OUTPUT);

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  digitalWrite(dirPin, HIGH);
  digitalWrite(enablePin, LOW);

  setup_wifi();

  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
}

void setup_wifi() {
  delay(10);
  Serial.println("Connecting to WiFi...");
  WiFi.begin("New Boys Hostel"," nithostel%boys");

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(".");
  }

  Serial.println("WiFi connected");
}

void callback(char* topic, byte* payload, unsigned int length) {
  String message;
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }
  Serial.print("Message arrived: ");
  Serial.println(message);

  if (String(topic) == topic_brake) {
    if (message == "STOP") {
      stopMotor();
    } else if (message == "START") {
      startMotor();
    }
  }
}

void startMotor() {
  digitalWrite(enablePin, LOW);
  digitalWrite(dirPin, HIGH);

  for (int i = 0; i < 2000; i++) {
    digitalWrite(stepPin, HIGH);
    delayMicroseconds(1000);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(1000);
  }

  Serial.println("Motor started!");
}

void stopMotor() {
  digitalWrite(enablePin, HIGH);
  Serial.println("Motor stopped!");
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;

  if (distance < 20) {
    String obstacleMsg = String(distance);
    client.publish(topic_obstacle, obstacleMsg.c_str());
    Serial.println("Obstacle detected: " + obstacleMsg + " cm");
  }

  delay(2000);
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("ESP32Client")) {
      Serial.println("connected");
      client.subscribe(topic_brake);
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      delay(5000);
    }
  }
}