#include <WiFi.h> //Enables the ESP32 to connect to a Wi-Fi netwrok 
#include <WiFiClient.h> //Handles the connection to a server over Wi-Fi
#include "ThingSpeak.h" //provides function to send and recive data to/from ThingSpeak
 
#define Low_LED_Pin 12 //name for GPIO pins conneted to the LED(red)
#define High_LED_Pin 14 //name for GPIO pins conneted to the LED(green)
#define PIN_TRIG 5 //GPIO pin used to send trigger signals to the ultrasonic sensor
#define PIN_ECHO 17 //GPIO pin used to read the echo signal from ultrasonic sensor

const char* WIFI_NAME = "Wokwi-GUEST"; //Wi-Fi credentials for connection
const char* WIFI_PASSWORD = ""; //Wi-Fi credentials for connection
const int myChannelNumber = 2786848 ;  //ThingSpeak channel ID
const char* myApiKey = "KXEX3ZBUWR5B44O9"; //API key for authenticating to ThingSpeak
const char* server = "api.thingspeak.com"; //Specifies the ThingSpeak server URL

WiFiClient client; //cretes a client object for establishing the connection to the ThingSpeak server

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200); //Intializes serial communication for debugging
  pinMode(Low_LED_Pin, OUTPUT); //Configures pin as OUTPUT or INPUT
  pinMode(High_LED_Pin, OUTPUT); //Configures pin as OUTPUT or INPUT
  pinMode(PIN_TRIG, OUTPUT); //Configures pin as OUTPUT or INPUT
  pinMode(PIN_ECHO, INPUT); //Configures pin as OUTPUT or INPUT
  WiFi.begin(WIFI_NAME, WIFI_PASSWORD); //Starts Wi-Fi connection with the specified credentials
  ThingSpeak.begin(client); //Links the client object to the ThingSpeak Library for data operations
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(PIN_TRIG, HIGH);  //sends 10 microsecond pulse to the trigger pin, activating the ultrasonic sensor
  delayMicroseconds(10); 
  digitalWrite(PIN_TRIG, LOW); 
 
  int duration = pulseIn(PIN_ECHO, HIGH); //Measures the duration of the echo pulse in microseconds
  int distance = duration / 58; //Converts the duration into distance in cm
  Serial.print("Distance in CM: "); //prints the calc distance to the monitor
  Serial.println(distance); 
  ThingSpeak.setField(1,distance); //sets the first field in ypur ThingSpeak channel with the distance vlaue
  ThingSpeak.writeFields(myChannelNumber,myApiKey); //.sends the data to the ThingSpeak channel
 
  if (distance < 20) { 
    digitalWrite(High_LED_Pin, HIGH); //distance less than 20 light green LED
    digitalWrite(Low_LED_Pin, LOW); 
  } 
  else if (distance >300){ 
    digitalWrite(Low_LED_Pin, HIGH);   //distance more than 300 light red LED
    digitalWrite(High_LED_Pin, LOW); 
  } 
  else{ 
    digitalWrite(High_LED_Pin, LOW); //if none no LED is lit
    digitalWrite(Low_LED_Pin, LOW); 
  } 
  delay(1000); //wait for 1 swcond before repeating the loop
}