#include <WiFi.h>
#include <PubSubClient.h>

const int RELAY_PIN = 4;
const int SWITCH_PIN = 5;

const char* ssid =  "Wokwi-GUEST";
const char* password = "";
const char* mqtt_server = "broker.hivemq.com";

const char* topic_command = "myUniqueSwitch123/command"; 
const char* topic_state   = "myUniqueSwitch123/state";

WiFiClient espClient;
PubSubClient client(espClient);

int relayState = LOW;
int currentSwitchState;
int lastSwitchState = HIGH;

unsigned long lastDebounceTime = 0;  
unsigned long debounceDelay = 50;

void mqttCallback(char* topic, byte* payload, unsigned int length) {
  String message;
  for (int i = 0; i < length; i++) {
    message += (char)payload[i];
  }
  Serial.print("Cloud Command Received: ");
  Serial.println(message);

  // If the cloud says ON, and we are currently OFF, turn it ON
  if (message == "ON" && relayState == LOW) {
    relayState = HIGH;
    digitalWrite(RELAY_PIN, relayState);
    client.publish(topic_state, "ON"); // Confirm back to cloud
  } 
  // If the cloud says OFF, and we are currently ON, turn it OFF
  else if (message == "OFF" && relayState == HIGH) {
    relayState = LOW;
    digitalWrite(RELAY_PIN, relayState);
    client.publish(topic_state, "OFF"); // Confirm back to cloud
  }
}


void reconnect() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    // Create a random client ID
    String clientId = "ESP32Client-";
    clientId += String(random(0, 0xffff), HEX);
    
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected to Cloud!");
      // Subscribe to our command topic so we can listen to the App
      client.subscribe(topic_command);
      // Publish our initial state
      client.publish(topic_state, relayState ? "ON" : "OFF");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

void setup() {
  // put your setup code here, to run once:

  Serial.begin(115200);
  Serial.println("started");
  pinMode(RELAY_PIN, OUTPUT);
  pinMode(SWITCH_PIN, INPUT_PULLUP);
  digitalWrite(RELAY_PIN, relayState); 

  // Connect to simulated Wi-Fi
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi Connected!");

  // Setup MQTT
  client.setServer(mqtt_server, 1883);
  client.setCallback(mqttCallback);
}



  
void loop() {
  // 1. Maintain Cloud Connection
  if (!client.connected()) {
    reconnect();
  }
  client.loop(); // Keeps the MQTT connection alive

  // 2. Read Physical Wall Switch (Edge Detection)
  int reading = digitalRead(SWITCH_PIN);

  if (reading != lastSwitchState) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > debounceDelay) {
    if (reading != currentSwitchState) {
      currentSwitchState = reading; 

      // EDGE DETECTED: Flip the relay state
      relayState = !relayState; 
      digitalWrite(RELAY_PIN, relayState);
      
      Serial.print("Wall Switch Flipped! Light is now: ");
      Serial.println(relayState ? "ON" : "OFF");

      // CRITICAL: Tell the cloud that the physical switch changed the light!
      client.publish(topic_state, relayState ? "ON" : "OFF");
    }
  }
  lastSwitchState = reading; 
}