#include "WiFi.h"
#include <HTTPClient.h>

const char* ssid = "Wokwi-GUEST";
const char* password = "";

const String url = "https://4ceb-41-251-102-134.eu.ngrok.io/bdia.php";



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

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;
float distanceInch;


unsigned long currentTime; 
unsigned long startTime = 0; 
unsigned long period = 3000;


void setup() {
  Serial.begin(115200); // Starts the serial communication
  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
  pinMode(echoPin, INPUT); // Sets the echoPin as an Input


  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }


  Serial.print("OK! IP=");
  Serial.println(WiFi.localIP());

}

void loop() {
  currentTime = millis();

  if (currentTime - startTime > period) {

    // Clears the trigPin
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    // Sets the trigPin on HIGH state for 10 micro seconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    
    // Reads the echoPin, returns the sound wave travel time in microseconds
    duration = pulseIn(echoPin, HIGH);
    
    // Calculate the distance
    distanceCm = duration * SOUND_SPEED/2;
    
    // Convert to inches
    distanceInch = distanceCm * CM_TO_INCH;
    
    // Prints the distance in the Serial Monitor
    Serial.print("Distance (cm): ");
    Serial.println(distanceCm);
    Serial.print("Distance (inch): ");
    Serial.println(distanceInch);

    
    if (distanceCm < 50) {
      HTTPClient http;
      http.begin(url);
      http.addHeader("Content-Type", "application/x-www-form-urlencoded");

      Serial.println("Sending data to server each 5s");
      char d = distanceCm;
      int status = http.POST("distance=" + String(distanceCm));
      delay(1000);
      Serial.print("HTTP ");
      Serial.println(status);

      String payload = http.getString();

      Serial.println();
      Serial.println(payload);
      
    }
    
    startTime = millis();
  }
}