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

// Wi-Fi credentials
const char* WIFI_NAME = "Wokwi-GUEST";  // Use "Wokwi-GUEST" for Wokwi simulation
const char* WIFI_PASSWORD = "";         // No password for Wokwi

// ThingSpeak credentials
const int myChannelNumber = 2944152; 
const char* myApiKey = "TS1MM4OZTGNVV9AQ";  
const char* server = "api.thingspeak.com"; 

// Ultrasonic sensor pins (same logical connections)
#define TRIG_PIN_1 5
#define ECHO_PIN_1 18
#define TRIG_PIN_2 19
#define ECHO_PIN_2 21
#define TRIG_PIN_3 2
#define ECHO_PIN_3 4

// Distance threshold (in cm)
#define THRESHOLD 50

WiFiClient client;

void setup() {
  Serial.begin(9600);

  // Configure ultrasonic sensor pins
  pinMode(TRIG_PIN_1, OUTPUT);
  pinMode(ECHO_PIN_1, INPUT);
  pinMode(TRIG_PIN_2, OUTPUT);
  pinMode(ECHO_PIN_2, INPUT);
  pinMode(TRIG_PIN_3, OUTPUT);
  pinMode(ECHO_PIN_3, INPUT);

  // Connect to Wi-Fi
  //WiFi.mode(WIFI_STA); // Set to station mode
  WiFi.begin(WIFI_NAME, WIFI_PASSWORD, 6);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
    // WiFi.begin("Wokwi-GUEST", "", 6);
  }
  Serial.println("Connected to WiFi!");
  Serial.print("Local IP: ");
  Serial.println(WiFi.localIP());

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

void loop() {
  // Get distances
  float distance1 = getDistance(TRIG_PIN_1, ECHO_PIN_1);
  float distance2 = getDistance(TRIG_PIN_2, ECHO_PIN_2);
  float distance3 = getDistance(TRIG_PIN_3, ECHO_PIN_3);

  // Determine parking status (1 = Occupied, 0 = Free)
  int status1 = (distance1 < THRESHOLD) ? 1 : 0;
  int status2 = (distance2 < THRESHOLD) ? 1 : 0;
  int status3 = (distance3 < THRESHOLD) ? 1 : 0;

  int alert = 0;
  if(status1 == 1 && status2 == 1 && status3 == 1){
    alert = 1;
    Serial.print("Alert: All parking areas are full!\n");
  }
  else{
    alert = 0;
  }

  // Print distances and statuses
  Serial.print("Distance 1: "); Serial.print(distance1); Serial.print(" cm | Status: "); Serial.println(status1 ? "Occupied" : "Free");
  Serial.print("Distance 2: "); Serial.print(distance2); Serial.print(" cm | Status: "); Serial.println(status2 ? "Occupied" : "Free");
  Serial.print("Distance 3: "); Serial.print(distance3); Serial.print(" cm | Status: "); Serial.println(status3 ? "Occupied" : "Free");

  // Send data to ThingSpeak
  ThingSpeak.setField(1, status1);
  ThingSpeak.setField(2, status2);
  ThingSpeak.setField(3, status3);
  ThingSpeak.setField(4, alert);
  
  int httpCode = ThingSpeak.writeFields(myChannelNumber, myApiKey);

  Serial.print("ThingSpeak Response: ");
  Serial.println(httpCode);

  if (httpCode == 200) {
      Serial.println("Data pushed successfully!");
  } else if (httpCode == -301) {
      Serial.println("Error: Invalid API key or incorrect server setup.");
  } else {
      Serial.println("Unknown error occurred.");
  }

  delay(15000);  
}

// Function to measure distance
float getDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  return duration * 0.017;  // Convert duration to distance (in cm)
}