#include <WiFi.h> 
#include <PubSubClient.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

const int TRIG_PIN = 5;   // Pin connected to ultrasonic sensor TRIG
const int ECHO_PIN = 18;   // Pin connected to ultrasonic sensor ECHO
const int LDR_PIN = 34;    // Pin connected to LDR (light sensor)

const char* ssid = "Wokwi-GUEST";  // Your Wi-Fi SSID
const char* password = "";         // Your Wi-Fi Password
const char* mqtt_server = "broker.hivemq.com";  // MQTT Broker

WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastDistMsg = 0; // Variable for ultrasonic reading interval
unsigned long lastLdrMsg = 0;  // Variable for LDR reading interval
float distance = 0;  // Distance variable for ultrasonic sensor
long duration;       // Duration for ultrasonic sensor pulse

// LCD setup using I2C
LiquidCrystal_I2C lcd(0x27, 16, 2);  // LCD display address, columns, rows

// Setup function for WiFi and MQTT
void setup_wifi() {
  delay(10);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  randomSeed(micros());

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

// Callback for incoming MQTT messages
void callback(char* topic, byte* payload, unsigned int length) {
  Serial.print("Message arrived [");
  Serial.print(topic);
  Serial.print("] ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);
  }
  Serial.println();
}

// Reconnect to the MQTT server if disconnected
void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    String clientId = "ESP32Client-";
    clientId += String(random(0xffff), HEX);
    if (client.connect(clientId.c_str())) {
      Serial.println("Connected");
      client.publish("/ThinkIOT/Publish", "Welcome");
      client.subscribe("/ThinkIOT/Subscribe");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}

// Function to determine waste level based on ultrasonic sensor distance
String determineWasteLevel(long distance) {
  const long MAX_HEIGHT = 30;  // Example: Change this based on actual container height in cm
  float fillPercentage = ((float)(MAX_HEIGHT - distance) / MAX_HEIGHT) * 100;

  if (fillPercentage < 20) {
    return "Waste Bin is full!";
  } else if (fillPercentage >= 20 && fillPercentage < 40) {
    return "Waste Bin is almost full.";
  } else if (fillPercentage >= 40 && fillPercentage < 60) {
    return "Waste Bin is halfway full.";
  } else if (fillPercentage >= 60 && fillPercentage < 80) {
    return "Waste Bin is nearly empty.";
  } else {
    return "Waste Bin is Empty.";
  }
}

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(LDR_PIN, INPUT);
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  // Initialize LCD
  lcd.init();   // Initialize the LCD
  lcd.backlight();  // Turn on the backlight for better visibility
  lcd.clear();   // Clear the LCD
  lcd.print("Connecting...");  // Display initial message
}

void loop() {
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  unsigned long now = millis();

  // Read distance data from ultrasonic sensor every 1 second
  if (now - lastDistMsg > 1000) {
    lastDistMsg = now;

    // Send trigger pulse
    digitalWrite(TRIG_PIN, LOW);
    delayMicroseconds(2);
    digitalWrite(TRIG_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIG_PIN, LOW);

    // Measure duration of pulse
    duration = pulseIn(ECHO_PIN, HIGH);
    distance = duration * 0.034 / 2; // Calculate distance in cm

    // Send the raw distance data to Node-RED
    String distanceStr = String(distance);
    client.publish("/ThinkIOT/distance", distanceStr.c_str());  // Sending the distance data to Node-RED

    // Output to Serial Monitor
    Serial.print("Distance: ");
    Serial.println(distance);

    // Determine waste level and message for display
    String wasteLevelMessage = determineWasteLevel(distance);

    // Display the waste level message on the LCD
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Dist: ");
    lcd.print(distance);
    lcd.print(" cm");

    lcd.setCursor(0, 1);
    lcd.print(wasteLevelMessage);
  }

  // Read LDR data (light sensor) every 2 seconds
  if (now - lastLdrMsg > 2000) {
    lastLdrMsg = now;
    
    int ldrValue = analogRead(LDR_PIN);
    
    // Adjust the backlight of the LCD based on LDR value
    if (ldrValue < 1000) {
      lcd.noBacklight();  // Low light -> turn off the backlight
    } else {
      lcd.backlight(); // Sufficient light -> turn on the backlight
    }

    // Output to Serial Monitor
    Serial.print("LDR Value: ");
    Serial.println(ldrValue);
  }
}