#include <WiFi.h>                // Include WiFi library to connect to the internet
#include <WiFiClient.h>          // Include WiFi client library for communication
#include <ThingSpeak.h>          // Include ThingSpeak library to send data to the cloud

// Wi-Fi credentials (network name and password)
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ThingSpeak channel details
unsigned long myChannelNumber = 2914414;   //channel number            
const char* myWriteAPIKey = "7D4F9BCU4N6V41PT";   //API key      

WiFiClient client;  // Create a WiFi client for ThingSpeak

// Define pins for the ultrasonic sensor
const int trigPin = 18;
const int echoPin = 19;

// Variables for distance calculation
long duration;
float cm;

void setup() {
  Serial.begin(115200);  // Start the serial monitor for debugging output
  
  pinMode(trigPin, OUTPUT);  // Set trig pin as output
  pinMode(echoPin, INPUT);   // Set echo pin as input

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

  ThingSpeak.begin(client);  // Initialize ThingSpeak connection
}

void loop() {
  // Send an ultrasonic pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure how long it takes for the echo to return
  duration = pulseIn(echoPin, HIGH);

  // Convert time to distance in cm
  cm = duration * 0.034 / 2;

  // Print the measured distance (water level) to the serial monitor
  Serial.print("Water Level (cm): ");
  Serial.println(cm);

  // Send the water level data to ThingSpeak (Field 1)
  ThingSpeak.setField(1, cm);
  int response = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

  // Check if data was sent successfully
  if (response == 200) {
    Serial.println("✅ Data sent to ThingSpeak!");
  } else {
    Serial.print("❌ Error sending data. Code: ");
    Serial.println(response);
  }

  delay(20000);  // Wait for 20 seconds before measuring and sending again
}