#include <ESP8266WiFi.h>             // Library to enable WiFi for ESP8266
#include <BlynkSimpleEsp8266.h>      // Blynk library for ESP8266 to connect and control via Blynk app
#include <OneWire.h>                 // OneWire library to communicate with the temperature sensor (DS18B20)
#include <DallasTemperature.h>       // DallasTemperature library to handle temperature data from the DS18B20 sensor
#include <LiquidCrystal_I2C.h>       // Library to control an I2C-based LCD display
LiquidCrystal_I2C lcd(0x27, 16, 2);  // Create an LCD object with I2C address 0x27, 16 columns, 2 rows

#define BLYNK_PRINT Serial           // Define Blynk print to use the Serial monitor
#define ONE_WIRE_BUS 12              // Define the data pin (GPIO12) where the DS18B20 temperature sensor is connected

int fanPin = 16;                     // Define the GPIO pin (GPIO16) where the fan is connected
int dutyCycle = 0;                   // Variable to store the PWM duty cycle for fan speed control

float temp = 0;                      // Variable to store the temperature value
int threshold = 30;                  // Default threshold temperature value (30°C)

OneWire oneWire(ONE_WIRE_BUS);       // Create a OneWire object to communicate with the temperature sensor
DallasTemperature sensors(&oneWire); // Create a DallasTemperature object to handle temperature readings

WidgetLED FAN(V0);                   // Create a virtual LED in the Blynk app to show fan status (V0 virtual pin)

char auth[] = "*********************"; // Blynk authentication token (replace with your token)
char ssid[] = "*********************"; // WiFi SSID (replace with your WiFi network name)
char pass[] = "*********************"; // WiFi password (replace with your WiFi password)

void setup() {
  Serial.begin(115200);              // Start the Serial monitor with baud rate of 115200 for debugging
  sensors.begin();                   // Start the temperature sensor
  pinMode(fanPin, OUTPUT);           // Set the fanPin as an OUTPUT pin to control the fan

  lcd.init();                        // Initialize the LCD
  lcd.backlight();                   // Turn on the LCD backlight
  lcd.setCursor(0, 0);               // Set the LCD cursor to the first row, first column
  lcd.print("  Temperature ");       // Display "Temperature" on the LCD
  lcd.setCursor(0, 1);               // Set the LCD cursor to the second row, first column
  lcd.print("Monitoring System");    // Display "Monitoring System" on the LCD
  delay(4000);                       // Wait for 4 seconds to let the message display
  lcd.clear();                       // Clear the LCD screen

  analogWriteRange(100);             // Set the range for PWM from 0 to 100 (for controlling fan speed)
  analogWriteFreq(10000);            // Set the PWM frequency to 10 kHz

  Blynk.begin(auth, ssid, pass, "blynk.cloud", 80); // Connect to Blynk cloud with the given credentials
}

BLYNK_WRITE(V7) {
  threshold = param.asInt();         // Read the threshold value from Blynk app (slider on virtual pin V7)
  Serial.print(" The Threshold value is: ");
  Serial.println(threshold);         // Print the new threshold value to the Serial monitor
  Serial.println();
}

void controlFanSpeed(int fanSpeedPercent) {
  analogWrite(fanPin, fanSpeedPercent);  // Adjust the fan speed using PWM according to the percentage

  Serial.print("Fan Speed: ");
  Serial.print(fanSpeedPercent);         // Print the current fan speed to the Serial monitor
  Serial.println("%");

  lcd.setCursor(0, 1);                   // Set the LCD cursor to the second row
  lcd.print("Fan Speed: ");
  lcd.print(fanSpeedPercent);            // Display the current fan speed on the LCD
  lcd.print("%");
}

void loop() {
  Blynk.run();                           // Run the Blynk process to handle communication with the Blynk app

  sensors.requestTemperatures();         // Request the temperature from the DS18B20 sensor
  temp = sensors.getTempCByIndex(0);     // Get the temperature in Celsius from the sensor (index 0 since only one sensor is connected)

  Serial.print("Temperature: ");
  Serial.print(temp);                    // Print the temperature value to the Serial monitor
  Serial.println("*C");

  lcd.setCursor(0, 0);                   // Set the LCD cursor to the first row
  lcd.print("Temp: ");
  lcd.print(temp);                       // Display the temperature value on the LCD
  lcd.print("*C");

  Blynk.virtualWrite(V3, temp);          // Send the temperature value to the Blynk app (virtual pin V3)

  if (temp >= threshold) {               // If the temperature exceeds or equals the threshold
    FAN.on();                            // Turn on the virtual LED on the Blynk app (indicating the fan is on)
    
    // Map the temperature to the fan speed: threshold (min) to 55°C (max) maps to 10% (min) to 100% (max) fan speed
    int fanSpeedPercent = map(temp, threshold, 55, 10, 100); 
    controlFanSpeed(fanSpeedPercent);    // Control the fan speed based on the temperature
    Blynk.virtualWrite(V4, fanSpeedPercent);  // Send the fan speed percentage to the Blynk app (virtual pin V4)
  }
  else if (temp < threshold) {           // If the temperature is below the threshold
    FAN.off();                           // Turn off the virtual LED on the Blynk app (indicating the fan is off)
    int fanSpeedPercent = 0;             // Set fan speed to 0%
    controlFanSpeed(fanSpeedPercent);    // Stop the fan
    Blynk.virtualWrite(V4, fanSpeedPercent);  // Send 0% fan speed to the Blynk app (virtual pin V4)
  }
}