#include <Arduino.h>
#include <DHT.h>

#define DHT_PIN 4      // DHT Sensor Pin
#define LED_R 16       // Red LED Pin
#define LED_G 17       // Green LED Pin
#define LED_B 18       // Blue LED Pin
#define BUZZER 19      // Buzzer Pin
#define SWITCH 21      // Slide Switch Pin

DHT dht(DHT_PIN, DHT22);

// Struct to hold sensor data
struct SensorData {
  float temperature;
  float humidity;
};

bool isAsleep = false;  // State to track sleep mode
unsigned long lastSwitchTime = 0;  // To debounce switch press
const unsigned long debounceDelay = 200;  // Debounce time (ms)

// RTC variable to track sleep state across wakeups
RTC_DATA_ATTR bool wakeUpFlag = false;

// Function Prototypes
SensorData readDHTData();
void updateLED(SensorData data);
void handleBuzzer(SensorData data);
void setColor(int red, int green, int blue);
void IRAM_ATTR handleSleepWakeup();  // Interrupt function
void goToSleep();          // Deep sleep function
void wakeUp();             // Wakeup function
void checkWakeupCause();   // Check wakeup cause

void setup() {
  Serial.begin(115200);
  dht.begin();

  pinMode(LED_R, OUTPUT);
  pinMode(LED_G, OUTPUT);
  pinMode(LED_B, OUTPUT);
  pinMode(BUZZER, OUTPUT);
  pinMode(SWITCH, INPUT_PULLUP);

  // Check for wakeup cause
  checkWakeupCause();

  // Check if the system woke up from deep sleep
  if (wakeUpFlag) {
    Serial.println("System Woke Up from Deep Sleep.");
    wakeUpFlag = false;  // Reset the flag after waking up
  } else {
    Serial.println("System Initialized.");
  }

  attachInterrupt(digitalPinToInterrupt(SWITCH), handleSleepWakeup, FALLING);  // Trigger on switch press
}

void loop() {
  // If system is asleep, do not continue further
  if (isAsleep) {
    Serial.println("Entering Deep Sleep Mode...");
    setColor(0, 0, 0);  // Turn off RGB LEDs before sleep
    delay(1000);  // Brief delay to allow message printing
    goToSleep();  // Call the goToSleep function to put the ESP32 in deep sleep
  } else {
    // Read sensor data every 2 seconds when awake
    unsigned long currentMillis = millis();
    static unsigned long previousMillis = 0;
    const long interval = 2000;  // 2 seconds

    if (currentMillis - previousMillis >= interval) {
      previousMillis = currentMillis;
      
      SensorData data = readDHTData();  // Read sensor data into struct

      if (isnan(data.humidity) || isnan(data.temperature)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
      }

      Serial.print("Humidity: ");
      Serial.print(data.humidity);
      Serial.print("%  Temperature: ");
      Serial.print(data.temperature);
      Serial.println("°C");

      updateLED(data);
      handleBuzzer(data);
    }
  }
}

void IRAM_ATTR handleSleepWakeup() {
  unsigned long currentMillis = millis();
  
  // Only process the switch toggle if debounce delay has passed
  if (currentMillis - lastSwitchTime > debounceDelay) {
    lastSwitchTime = currentMillis;
    isAsleep = !isAsleep;  // Toggle the sleep state
    if (isAsleep) {
      
      wakeUpFlag = true;  // Set wakeup flag to true before deep sleep
    } else {
      
      wakeUp();  // Call the wakeUp function when switching back from sleep
    }
  }
}

SensorData readDHTData() {
  SensorData data;
  data.humidity = dht.readHumidity();
  data.temperature = dht.readTemperature();
  return data;
}

void updateLED(SensorData data) {
  // Only update LED if the system is awake
  if (isAsleep) return;  // Skip if in deep sleep mode
  
  if (data.humidity < 40) {
    setColor(0, 0, 255); // Blue
    Serial.println("Blue LED ON - Humidity < 40%");
  } else if (data.humidity >= 40 && data.humidity <= 60) {
    setColor(0, 255, 0); // Green
    Serial.println("Green LED ON - Humidity 40-60%");
  } else if (data.humidity > 60 && data.humidity <= 70) {
    setColor(255, 0, 0); // Red
    Serial.println("Red LED ON - Humidity > 60%");
  } else if (data.humidity > 70) {
    setColor(255, 0, 0); // Red
    Serial.println("Red LED ON - Humidity > 70% - Critical");
  }
}

void handleBuzzer(SensorData data) {
  if (data.humidity > 60) {
    digitalWrite(BUZZER, HIGH); // Short beep
    Serial.println("Buzzer ON - High Humidity");
  } else if (data.humidity > 70) {
    digitalWrite(BUZZER, HIGH); // Continuous beep
    Serial.println("Buzzer ON - Critical Humidity");
  } else {
    digitalWrite(BUZZER, LOW);
  }

  if (data.temperature > 30.0) {
    digitalWrite(BUZZER, HIGH); // Short beep
    Serial.println("Buzzer ON - High Temperature");
  }
}

void setColor(int red, int green, int blue) {
  digitalWrite(LED_R, red);
  digitalWrite(LED_G, green);
  digitalWrite(LED_B, blue);
}

// Function to put ESP32 into deep sleep
void goToSleep() {
  // Disable any automatic wakeup timers and use GPIO wakeup
  Serial.println("Disabling automatic wakeup timers");
  
  // Set the wakeup source to be the SWITCH pin (GPIO 21 is for the switch)
  esp_sleep_enable_ext0_wakeup(GPIO_NUM_21, 0);  // Pin 21 is the switch (active low)
  
  Serial.println("Entering deep sleep...");
  esp_deep_sleep_start();  // Enter deep sleep mode
}

// Function to handle wakeup after deep sleep
void wakeUp() {
  // ESP32 wakes up automatically and resumes from where it left off
  Serial.println("ESP32 woke up from deep sleep");
}

// Function to check wakeup cause
void checkWakeupCause() {
  esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
  switch (cause) {
    case ESP_SLEEP_WAKEUP_EXT0: 
      Serial.println("Woke up due to GPIO external interrupt");
      break;
    case ESP_SLEEP_WAKEUP_EXT1: 
      Serial.println("Woke up due to GPIO external interrupt (EXT1)");
      break;
    case ESP_SLEEP_WAKEUP_TIMER: 
      Serial.println("Woke up due to timer");
      break;
    default: 
      Serial.println("Woke up due to unknown cause");
      break;
  }
}