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

int TRIG_PIN = 14; // ESP32 pin GPIO23 connected to Ultrasonic Sensor's TRIG pin
int ECHO_PIN = 27; // ESP32 pin GPIO22 connected to Ultrasonic Sensor's ECHO pin

float duration_us, distance_cm;
float cal_distance();

char ssid[] = "Wokwi-GUEST";
char pass[] = "";
WiFiClient client;
unsigned long myChannelNumber = 2580525;
const char * myWriteAPIKey = "DJQJRHIORQTZBNLP";
int statusCode;

void setup() {
  // begin serial port
  Serial.begin (115200);
  WiFi.mode(WIFI_STA);
  ThingSpeak.begin(client);

  // configure the trigger pin to output mode
  pinMode(TRIG_PIN, OUTPUT);
  // configure the echo pin to input mode
  pinMode(ECHO_PIN, INPUT);

  pinMode(5, OUTPUT);

  if(WiFi.status() != WL_CONNECTED)
  {
    Serial.print("Attempting to connect");
    while(WiFi.status() != WL_CONNECTED)
    {
    WiFi.begin(ssid, pass); 
    Serial.print(".");
    delay(5000);
    }
  Serial.println("\nConnected.");
  }

}

void loop() {
  distance_cm = cal_distance();
  Serial.print("distance: ");
  Serial.print(distance_cm);
  Serial.println(" cm");

  ThingSpeak.setField(1, distance_cm);

  if((distance_cm>=200)||(distance_cm<=50))
  {
    digitalWrite(5, HIGH);
  }
  else
  {
    digitalWrite(5, LOW);
  }

  statusCode = ThingSpeak.writeFields(myChannelNumber,myWriteAPIKey);
  

  if(statusCode == 200) { //successful writing code
    Serial.println("Channel update successful.");
  }
  else {
    Serial.println("Problem Writing data. HTTP error code :" +
    String(statusCode));
  }
  delay(100);

}

float cal_distance()
{
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  // generate 10-microsecond pulse to TRIG pin
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  //digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin
  duration_us = pulseIn(ECHO_PIN, HIGH);

  // return the distance
  return( (0.034 * duration_us)/2);
}