#define BLYNK_TEMPLATE_ID           "TMPL6SZpMNJxe"
#define BLYNK_TEMPLATE_NAME         "Real Time Environmental Sensing and Control"
#define BLYNK_AUTH_TOKEN            "CjyYn6P9lOIkOa75qlaRPwKb6cPr_vvu"

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>
#include <DHT.h>  // Library for DHT22 sensor

// Your WiFi credentials
char ssid[] = "Wokwi-GUEST";
char pass[] = "";

// Pin Definitions
#define DHTPIN 23               // GPIO pin for DHT22 data
#define DHTTYPE DHT22           // Define the DHT sensor type
#define TRIGPIN 12              // GPIO pin for HC-SR04 Trig
#define ECHOPIN 14              // GPIO pin for HC-SR04 Echo
#define LDRPIN 34               // ADC pin for LDR (ensure it's connected to an analog input pin)
#define RELAYPIN 16             // GPIO pin for Relay control
#define BUTTONPIN 18            // GPIO pin for manual control button

// Initialize the DHT22 sensor
DHT dht(DHTPIN, DHTTYPE);

// Variables for sensors
float temperature;
float humidity;
long duration;
float distance;
int lightLevel;
bool manualControl = false;     // Manual HVAC control flag
float thresholdDistance = 200.0;
int lightThreshold = 500;

// Timeout-related variables
unsigned long lastMovementTime = 0;  // Track the last time movement was detected
unsigned long timeoutDuration = 300000;  // Timeout period for lights (5 minutes)

// Variables for scheduling feature
int currentHour = 9;            // Starting at 9 AM (simulated time)
int lightSamples[10];           // Buffer to store light readings
int sampleIndex = 0;
int totalLight = 0;

// Temperature thresholds for HVAC control
float upperTempThreshold = 28.0; // HVAC turns ON above this temperature
float lowerTempThreshold = 25.0; // HVAC turns OFF below this temperature

// Blynk timer instance
BlynkTimer timer;

// Virtual pin assignments from Blynk interface
#define VIRTUAL_PIN_TEMP V0
#define VIRTUAL_PIN_HUMIDITY V1
#define VIRTUAL_PIN_OCCUPANCY V2
#define VIRTUAL_PIN_LIGHT V3
#define VIRTUAL_PIN_RELAY V4

// This function sends Arduino's up time every second to Virtual Pin (5).
void myTimerEvent() {
  Blynk.virtualWrite(V5, millis() / 1000);
}

void setup() {
  // Debug console
  Serial.begin(115200);

  // Initialize Blynk
  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  // Initialize sensors
  dht.begin();

  // Set pin modes
  pinMode(TRIGPIN, OUTPUT);
  pinMode(ECHOPIN, INPUT);
  pinMode(RELAYPIN, OUTPUT);
  pinMode(BUTTONPIN, INPUT_PULLUP);  // Manual button for HVAC control

  // Relay starts in OFF position
  digitalWrite(RELAYPIN, LOW);

  // Setup a function to be called every second
  timer.setInterval(1000L, myTimerEvent);

  Serial.println(F("System Initialized!"));
  printUserGuide();  // Print the user guide on startup
}

void loop() {
  // Simulate the passage of time
  currentHour++;
  if (currentHour > 23) {
    currentHour = 0;  // Reset at midnight
  }

  // Run Blynk
  Blynk.run();
  timer.run(); // Initiates BlynkTimer

  // Read sensors separately to avoid overloading
  readTemperatureHumidity();
  readUltrasonicDistance();
  readLightLevel();
  checkManualControl();
  controlRelay();
  controlScheduler();  // Handle scheduling for HVAC system
  printSystemStatus(); // Enhanced UI feedback

  delay(3000);  // 3 seconds delay to avoid constant polling and memory overload
}

void printUserGuide() {
  Serial.println(F("\nUser Guide:"));
  Serial.println(F("1. DHT22 measures temperature and humidity."));
  Serial.println(F("2. HC-SR04 detects occupancy (distance)."));
  Serial.println(F("3. LDR measures light levels."));
  Serial.println(F("4. Relay controls HVAC based on temperature or manual mode."));
  Serial.println(F("5. Press the button to toggle between manual and automatic HVAC control."));
  Serial.println(F("6. System operates automatically between 9 AM and 5 PM."));
  Serial.println(F("7. HVAC operates based on a temperature range (25°C to 28°C).\n"));
}

void readTemperatureHumidity() {
  // Reading temperature and humidity from DHT22
  temperature = dht.readTemperature();
  humidity = dht.readHumidity();

  if (isnan(temperature) || isnan(humidity)) {
    Serial.println(F("Failed to read from DHT sensor!"));
  } else {
    Serial.print(F("Temperature: "));
    Serial.print(temperature);
    Serial.print(F(" °C, Humidity: "));
    Serial.print(humidity);
    Serial.println(F(" %"));

    // Send temperature and humidity to Blynk
    Blynk.virtualWrite(VIRTUAL_PIN_TEMP, temperature);
    Blynk.virtualWrite(VIRTUAL_PIN_HUMIDITY, humidity);
  }
}

void readUltrasonicDistance() {
  // Reading distance from HC-SR04
  digitalWrite(TRIGPIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGPIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGPIN, LOW);
  duration = pulseIn(ECHOPIN, HIGH);
  distance = (duration * 0.034 / 2);  // Convert to cm

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

  // Send occupancy status to Blynk
  Blynk.virtualWrite(VIRTUAL_PIN_OCCUPANCY, distance);

  // Occupancy-based control: Detect movement and reset timeout
  if (distance < thresholdDistance) {
    lastMovementTime = millis();  // Reset the timer on movement detection
    Serial.println(F("Movement detected. Resetting timeout."));
  }

  // Turn off HVAC and lights if no movement for the timeout period
  if (millis() - lastMovementTime > timeoutDuration) {
    Serial.println(F("No occupancy detected for 5 minutes. Turning off HVAC and lights."));
    digitalWrite(RELAYPIN, LOW);  // Turn off the relay (lights and HVAC)
  }
}

void readLightLevel() {
  // Reading light level from LDR
  totalLight -= lightSamples[sampleIndex];  // Subtract the oldest sample
  lightSamples[sampleIndex] = analogRead(LDRPIN);  // Read the new sample
  totalLight += lightSamples[sampleIndex];  // Add the new sample
  sampleIndex = (sampleIndex + 1) % 10;     // Circular buffer
  int avgLightLevel = totalLight / 10;      // Calculate the average light level

  Serial.print(F("Light Level (Avg): "));
  Serial.println(avgLightLevel);

  // Send light levels to Blynk
  Blynk.virtualWrite(VIRTUAL_PIN_LIGHT, avgLightLevel);

  // Dimming logic based on light level
  if (avgLightLevel > lightThreshold) {
    Serial.println(F("Dimming lights due to high ambient light."));
    digitalWrite(RELAYPIN, LOW);  // Turn off the relay (dimming lights)
  } else {
    Serial.println(F("Turning on lights due to low ambient light."));
    digitalWrite(RELAYPIN, HIGH);  // Turn on the relay
  }
}

void checkManualControl() {
  if (digitalRead(BUTTONPIN) == LOW) {   // If button is pressed
    manualControl = !manualControl;      // Toggle manual control
    Serial.print(F("Manual control "));
    Serial.println(manualControl ? "ON" : "OFF");
    delay(500);  // Debounce delay
  }
}

void controlRelay() {
  if (manualControl) {
    Serial.println(F("Manual control active: Relay OFF."));
    digitalWrite(RELAYPIN, LOW);  // Manual control overrides automatic
    Blynk.virtualWrite(VIRTUAL_PIN_RELAY, 0);
  } else {
    if (temperature > upperTempThreshold) {
      digitalWrite(RELAYPIN, HIGH);   // Turn relay ON
      Serial.println(F("Relay ON: Temperature is above 28°C"));
      Blynk.virtualWrite(VIRTUAL_PIN_RELAY, 1);
    } else if (temperature < lowerTempThreshold) {
      digitalWrite(RELAYPIN, LOW);    // Turn relay OFF
      Serial.println(F("Relay OFF: Temperature is below 25°C"));
      Blynk.virtualWrite(VIRTUAL_PIN_RELAY, 0);
    }
  }
}

void controlScheduler() {
  // Simulate scheduling: HVAC is on between 9 AM and 5 PM
  if (currentHour >= 9 && currentHour <= 17) {
    Serial.println(F("Within working hours (9 AM - 5 PM): Relay ON"));
    digitalWrite(RELAYPIN, HIGH);  // Turn on the HVAC system
  } else {
    Serial.println(F("Outside working hours: Relay OFF"));
    digitalWrite(RELAYPIN, LOW);   // Turn off the HVAC system
  }
}
// Print system status
void printSystemStatus() {
  Serial.println(F("============================="));
  Serial.println(F("     SYSTEM STATUS UPDATE     "));
  Serial.println(F("============================="));
  Serial.print(F("Current Hour (Simulated): "));
  Serial.println(currentHour);

  Serial.print(F("Temperature: "));
  Serial.print(temperature);
  Serial.println(F(" °C"));

  Serial.print(F("Light Level: "));
  Serial.println(totalLight / 10);

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

  Serial.print(F("Relay Status: "));
  Serial.println(digitalRead(RELAYPIN) == HIGH ? "ON" : "OFF");
  Serial.println(F("=============================\n"));
}