#include <WiFi.h>
#include <ThingSpeak.h>

// Ultrasonic Sensor Pins
#define trigPin 5     // Trigger pin
#define echoPin 18    // Echo pin

// Wi-Fi
const char* ssid = "Wokwi-GUEST";     // Change as needed
const char* password = "";            // Change as needed

// ThingSpeak
WiFiClient client;
unsigned long channelID = 2869806;       // Change to your ThingSpeak channel ID
const char* writeAPIKey = "6Y3JTFY09CMPEMNC";  // Change to your Write API Key

void setup() {
  Serial.begin(115200);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  WiFi.begin(ssid, password);
  Serial.print("Connecting to Wi-Fi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(1000);
  }
  Serial.println("\nWi-Fi Connected");

  ThingSpeak.begin(client);
}

void loop() {
  long duration;
  float distance;

  // Trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo
  duration = pulseIn(echoPin, HIGH);

  // Calculate distance in cm
  distance = duration * 0.0343 / 2;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check for space availability
  String dockStatus;
  if (distance < 100) {   // Example threshold
    dockStatus = "OCCUPIED";
  } else {
    dockStatus = "AVAILABLE";
  }

  Serial.print("Dock Status: ");
  Serial.println(dockStatus);

  // ✅ Send distance to ThingSpeak Field 2
  ThingSpeak.setField(2, distance);  // Sending only distance as you mentioned

  int statusCode = ThingSpeak.writeFields(channelID, writeAPIKey);

  if (statusCode == 200) {
    Serial.println("ThingSpeak update successful.");
  } else {
    Serial.print("Problem updating channel. HTTP error code: ");
    Serial.println(statusCode);
  }

  delay(15000); // ThingSpeak minimum update interval is 15 seconds
}