#define BLYNK_TEMPLATE_ID "TMPL6mW7nWxRf"
#define BLYNK_TEMPLATE_NAME "Water Level2"
#define BLYNK_AUTH_TOKEN "XM4z4sg4DQVo77uDLnSgNLrY1VeMhFbR"

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <WiFi.h>
#include <BlynkSimpleEsp32.h>
#include <HTTPClient.h>  // For sending data to ThingSpeak

// Initialize LCD with I2C address, columns, and rows
LiquidCrystal_I2C lcd(0x27, 16, 2);  // Adjust the I2C address if needed

// Ultrasonic sensor pins for ESP32
const int trigPin = 18;  // GPIO pin for trigger (adjust as per wiring)
const int echoPin = 19;  // GPIO pin for echo (adjust as per wiring)

// Battery voltage pin and settings
const int batteryPin = 34;  // Analog pin connected to potentiometer wiper
const float maxBatteryVoltage = 5.0;  // Maximum expected battery voltage
const float referenceVoltage = 3.3;   // ESP32 reference voltage
const int adcResolution = 4095;       // ADC resolution for ESP32
const float lowBatteryThreshold = 4.5;  // Voltage threshold for low battery warning

// Tank dimensions (adjust based on your tank's actual height)
const float tankHeight = 500.0; // Height of the tank in cm

// WiFi and Blynk credentials
char ssid[] = "Wokwi-GUEST";
char pass[] = "";
char auth[] = BLYNK_AUTH_TOKEN;  // Use defined Blynk Auth Token

// ThingSpeak credentials
const char* thingSpeakAPIKey = "0B18ROG1LWRCMEXY";  // Replace with your ThingSpeak API key
const char* server = "http://api.thingspeak.com/update";

float readBatteryVoltage() {
  int rawReading = analogRead(batteryPin);
  float voltageRatio = maxBatteryVoltage / referenceVoltage;
  float batteryVoltage = (rawReading / (float)adcResolution) * referenceVoltage * voltageRatio;
  return batteryVoltage;
}

void setup() {
  lcd.init();  // Initialize LCD with I2C
  lcd.backlight();  // Turn on the backlight
  lcd.setCursor(0, 0);
  lcd.print("Tank Level:");

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  Serial.begin(115200);  // Higher baud rate for ESP32

  // Connect to WiFi
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, pass);
  unsigned long startAttemptTime = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startAttemptTime < 15000) {
    delay(500);
    Serial.print(".");
  }
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nConnected to WiFi");
  } else {
    Serial.println("\nFailed to connect to WiFi");
  }

  Blynk.config(auth);
  if (Blynk.connect()) {
    Serial.println("Connected to Blynk");
  } else {
    Serial.println("Failed to connect to Blynk");
  }
}

void loop() {
  Blynk.run();

  float batteryVoltage = readBatteryVoltage();
  Serial.print("Battery Voltage: ");
  Serial.print(batteryVoltage, 2);
  Serial.println(" V");

  // Always send battery level to Blynk
  if (batteryVoltage <= lowBatteryThreshold) {
    Blynk.virtualWrite(V3, String("Low Battery: ") + String(batteryVoltage, 2) + "V");
  } else {
    Blynk.virtualWrite(V3, String("Battery Voltage: ") + String(batteryVoltage, 2) + "V");
  }

  lcd.clear();
  if (batteryVoltage <= lowBatteryThreshold) {
    lcd.setCursor(0, 0);
    lcd.print("LOW BATTERY");
    lcd.setCursor(0, 1);
    lcd.print("Voltage: ");
    lcd.print(batteryVoltage, 2);
    lcd.print("V");
    delay(5000);  // Display LOW BATTERY warning for 5 seconds
  } else {
    lcd.setCursor(0, 0);
    lcd.print("Battery Voltage:");
    lcd.setCursor(0, 1);
    lcd.print(batteryVoltage, 2);
    lcd.print("V");
    delay(5000);
  }

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  long duration = pulseIn(echoPin, HIGH);
  float distance = (duration * 0.0343) / 2;  // Convert time to distance in cm

  float waterLevel = tankHeight - distance;
  if (waterLevel < 0) waterLevel = 0;
  if (waterLevel > tankHeight) waterLevel = tankHeight;

  float percentage = (waterLevel / tankHeight) * 100;

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  Serial.print("Water Level: ");
  Serial.print(waterLevel);
  Serial.println(" cm");

  Serial.print("Percentage: ");
  Serial.print(percentage);
  Serial.println("%");

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Tank Level:");

  lcd.setCursor(0, 1);
  lcd.print("Level: ");
  lcd.print(percentage, 1);
  lcd.print("%   ");

  Blynk.virtualWrite(V2, percentage);   // Send percentage to Virtual Pin 2

  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    String url = String(server) + "?api_key=" + thingSpeakAPIKey + "&field1=" + String(percentage);
    http.begin(url);
    int httpResponseCode = http.GET();

    if (httpResponseCode > 0) {
      Serial.print("ThingSpeak Response Code: ");
      Serial.println(httpResponseCode);
    } else {
      Serial.print("Error sending to ThingSpeak: ");
      Serial.println(http.errorToString(httpResponseCode).c_str());
    }

    http.end();
  }

  delay(15000);
}