//Monitoring the Tank water level
#include <WiFi.h>
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
#include <EEPROM.h>
#include <LiquidCrystal_I2C.h>

// Function prototypes
long microsecondsToInches(long microseconds);
long microsecondsToCentimeters(long microseconds);
void connectToWiFi();
void printWiFiStatus();
void connectToAdafruit();

// Initialize I2C LCD (change address if needed)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Adafruit IO credentials
#define AIO_SERVER      "io.adafruit.com"  // adafruit server
#define AIO_SERVERPORT  1883
#define AIO_USERNAME    "kamaladhi"      //adafruit username
#define AIO_KEY         "aio_TWZW3153YXMV2m3w2FGhLoFLxTiT"   //adafruit api key

//MQTT is used here 
WiFiClient client;
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);
Adafruit_MQTT_Publish send = Adafruit_MQTT_Publish(&mqtt, AIO_USERNAME "/feeds/water-level");

// Pin definitions
const int trigPin = 13; // ultrasonic sensor trigger pin
const int echoPin = 12; // ultrasonic sensor echo pin
const int relayPin = 14; //relay pin
int lastPublishedPercentage = -1;

// Variables declaration
long duration, inches;
int set_val, percentage;
bool pump;

// WiFi credentials
const char* ssid = "Wokwi-GUEST";     
const char* password = ""; 

void setup() {
  Serial.begin(115200);
  delay(1000); // Wait for serial monitor

  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.print("Initializing...");

  // Initialize pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, HIGH); // Relay off initially

  // Initialize EEPROM
  EEPROM.begin(512);
  set_val = EEPROM.read(0);
  if (set_val > 150 || set_val <= 0) {
    set_val = 100; // Default value
    EEPROM.write(0, set_val);
    EEPROM.commit();
  }

  // Connect to WiFi
  connectToWiFi();

  // Initialize MQTT
  if (WiFi.status() == WL_CONNECTED) {
    connectToAdafruit();
  }
}

void loop() {
  // Check WiFi connection
  if (WiFi.status() != WL_CONNECTED) {
    lcd.clear();
    lcd.print("WiFi Disconnected");
    printWiFiStatus();
    connectToWiFi();
    delay(5000);
    return;
  }

  // Check MQTT connection
  if (!mqtt.ping(3) && !mqtt.connected()) {
    lcd.clear();
    lcd.print("MQTT Disconnected");
    connectToAdafruit();
    delay(5000);
    return;
  }

  // Read water level
  digitalWrite(trigPin, LOW);  //trig pin of ultrasonic sensor
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH, 30000); // 30ms timeout
  if (duration == 0) {
    Serial.println("Sensor timeout");
    lcd.clear();
    lcd.print("Sensor Error");
    delay(2000);
    return;
  }

 //converts the timetaken for the ultrasonic pulse to bounce back into inches
  inches = microsecondsToInches(duration);  
  percentage = (set_val - inches) * 100 / set_val;//Calculates the water level percentage
  percentage = constrain(percentage, 0, 100);

  // Display water level
  lcd.clear();
  lcd.print("WATER LEVEL:");
  lcd.setCursor(12, 0);
  lcd.print(percentage);
  lcd.print("%");
  
  // Control pump
  pump = (percentage < 30);
  digitalWrite(relayPin, !pump);
  
  lcd.setCursor(0, 1);
  lcd.print("PUMP: ");
  lcd.print(pump ? "ON " : "OFF");


  // Publish to Adafruit IO
  if (abs(percentage - lastPublishedPercentage) >= 1) {
    if (!send.publish((int32_t)percentage)) {
      Serial.println("Publish failed");
    } else {
      Serial.println("Published");
      lastPublishedPercentage = percentage; // Update last published value
    }
  }
  delay(2000); // Wait between readings
}
// Error Handling ....................................................................
// WiFi connection function
void connectToWiFi() {
  Serial.println("\nConnecting to WiFi...");
  lcd.clear();
  lcd.print("Connecting WiFi");

  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);
  WiFi.begin(ssid, password);

  unsigned long startTime = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startTime < 20000) {
    delay(500);
    Serial.print(".");
    lcd.print(".");
  }

  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nConnected!");
    Serial.print("IP: ");
    Serial.println(WiFi.localIP());
    lcd.clear();
    lcd.print("WiFi Connected");
    lcd.setCursor(0, 1);
    lcd.print("IP: ");
    lcd.print(WiFi.localIP().toString());
    delay(2000);
  } else {
    Serial.println("\nConnection Failed!");
    lcd.clear();
    lcd.print("WiFi Failed!");
    printWiFiStatus();
  }
}

// Adafruit IO connection function
void connectToAdafruit() {
  Serial.print("Connecting to Adafruit IO... ");
  lcd.clear();
  lcd.print("Connecting MQTT");

  int8_t ret;
  int attempts = 0;
  
  while ((ret = mqtt.connect()) != 0 && attempts < 3) {
    attempts++;
    switch (ret) {
      case 1: Serial.println("Wrong protocol"); break;
      case 2: Serial.println("ID rejected"); break;
      case 3: Serial.println("Server unavailable"); break;
      case 4: Serial.println("Bad credentials"); break;
      default: Serial.println("Connection failed"); break;
    }
    
    lcd.clear();
    lcd.print("MQTT Fail ");
    lcd.print(attempts);
    delay(5000);
  }

  if (mqtt.connected()) {
    Serial.println("Connected!");
    lcd.clear();
    lcd.print("MQTT Connected");
    delay(1000);
  } else {
    Serial.println("Failed after 3 attempts");
    lcd.clear();
    lcd.print("MQTT Failed");
  }
}

// WiFi status printer
void printWiFiStatus() {
  Serial.print("WiFi Status: ");
  switch(WiFi.status()) {
    case WL_NO_SHIELD: Serial.println("No WiFi shield"); break;
    case WL_IDLE_STATUS: Serial.println("Idle"); break;
    case WL_NO_SSID_AVAIL: Serial.println("SSID not available"); break;
    case WL_SCAN_COMPLETED: Serial.println("Scan completed"); break;
    case WL_CONNECTED: Serial.println("Connected"); break;
    case WL_CONNECT_FAILED: Serial.println("Connect failed"); break;
    case WL_CONNECTION_LOST: Serial.println("Connection lost"); break;
    case WL_DISCONNECTED: Serial.println("Disconnected"); break;
    default: Serial.println("Unknown status"); break;
  }
}
//...........................................................................
//helper functions :
// Conversion functions
long microsecondsToInches(long microseconds) {
  return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds) {
  return microseconds / 29 / 2;
}