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

// --- Pin Definitions (Corrected) ---
#define DHT_PIN 15
#define DHT_TYPE DHT22
#define IR_RECEIVE_PIN 23    // MOVED to a safe, non-ADC2 pin
#define SMOKE_PIN 34
#define METHANE_PIN 35
#define CO_PIN 32
#define LDR_PIN 36
#define BUTTON_PIN 5

// --- Sensor Objects ---
DHT dht(DHT_PIN, DHT_TYPE);

// --- Hazard & Alert Logic ---
enum HazardLevel { SAFE, ALERT };
HazardLevel currentHazard = SAFE;
volatile bool isAlarmMuted = false;

// --- THRESHOLDS (CRITICAL: These are placeholders and MUST be calibrated) ---
// Calibrate by noting the sensor's reading in clean air, then in a test environment.
const int SMOKE_THRESHOLD = 1500;
const int METHANE_THRESHOLD = 1800;
const int CO_THRESHOLD = 1600;

// --- Non-Blocking Timers ---
unsigned long previousSensorReadMillis = 0;
const long sensorReadInterval = 2000; // Read sensors every 2 seconds

unsigned long lastButtonPressMillis = 0;
const long debounceDelay = 50; // Debounce time for button

void setup() {
  Serial.begin(115200);
  Serial.println("ShieldSense System Initialized (Corrected Version)");

  dht.begin();

  // Initialize IR receiver on the new, safe pin
  IrReceiver.begin(IR_RECEIVE_PIN, ENABLE_LED_FEEDBACK);
  
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(SMOKE_PIN, INPUT);
  pinMode(METHANE_PIN, INPUT);
  pinMode(CO_PIN, INPUT);
  pinMode(LDR_PIN, INPUT);
}

void loop() {
  unsigned long currentMillis = millis();

  // --- Handle Inputs (Non-Blocking) ---
  handleButton();
  handleIR();

  // --- Timed Sensor Reading (Non-Blocking) ---
  if (currentMillis - previousSensorReadMillis >= sensorReadInterval) {
    previousSensorReadMillis = currentMillis;
    
    // Read all sensors
    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();
    int smokeVal = analogRead(SMOKE_PIN);
    int methaneVal = analogRead(METHANE_PIN);
    int coVal = analogRead(CO_PIN);
    int ldrVal = analogRead(LDR_PIN);

    // Check for sensor read errors
    if (isnan(humidity) || isnan(temperature)) {
      Serial.println("Failed to read from DHT sensor!");
    }

    // Evaluate the hazard level based on new readings
    if (smokeVal > SMOKE_THRESHOLD || methaneVal > METHANE_THRESHOLD || coVal > CO_THRESHOLD) {
      currentHazard = ALERT;
    } else {
      currentHazard = SAFE;
    }

    // Display the updated status
    printStatus(temperature, humidity, smokeVal, methaneVal, coVal, ldrVal);
    
    // Trigger the alarm if necessary
    triggerAlarm();
  }
}

// --- Input Handling Functions ---

void handleButton() {
  // Non-blocking button press check with debounce
  if (millis() - lastButtonPressMillis > debounceDelay) {
    if (digitalRead(BUTTON_PIN) == LOW) {
      toggleMute();
      lastButtonPressMillis = millis(); // Reset debounce timer
    }
  }
}

void handleIR() {
  // NOTE: The LDR logic to disable the IR receiver is kept as requested,
  // but consider if this feature is truly necessary for your project.
  int ldrVal = analogRead(LDR_PIN);
  if (ldrVal < 500) { // Dark environment
    IrReceiver.start();
    if (IrReceiver.decode()) {
      Serial.print("IR Code Received: 0x");
      Serial.println(IrReceiver.decodedIRData.decodedRawData, HEX);
      toggleMute();
      IrReceiver.resume(); // Prepare for the next signal
    }
  } else { // Light environment
    IrReceiver.stop();
  }
}

// --- Alert & Mute Functions ---

void toggleMute() {
  isAlarmMuted = !isAlarmMuted;
  if (isAlarmMuted) {
    Serial.println(">>>> ALARM MUTED <<<<");
  } else {
    Serial.println(">>>> ALARM UNMUTED <<<<");
  }
}

void triggerAlarm() {
  if (currentHazard == ALERT && !isAlarmMuted) {
    // This is where you would activate a real buzzer or light
    Serial.println("!!! HAZARD DETECTED - ALARM ACTIVE !!!");
  }
}

// --- Display Function ---

void printStatus(float temp, float hum, int smoke, int methane, int co, int ldr) {
  Serial.print("Temp: ");
  Serial.print(temp, 1);
  Serial.print("°C | Hum: ");
  Serial.print(hum, 1);
  Serial.print("% | Smoke: ");
  Serial.print(smoke);
  Serial.print(" | Methane: ");
  Serial.print(methane);
  Serial.print(" | CO: ");
  Serial.print(co);
  Serial.print(" | LDR: ");
  Serial.print(ldr);

  if (currentHazard == ALERT) {
    Serial.print(" -> [ALERT]");
  } else {
    Serial.print(" -> [SAFE]");
  }
  Serial.println();
}