#include <Wire.h>
#include <BH1750.h>
#include <OneWire.h>
#include <DallasTemperature.h>

// Pin Definitions
const int buttonPin = 13;     // Pin where the button is connected
const int ledPin = 12;        // Pin where the LED is connected
const int buzzerPin = 14;     // Pin where the buzzer is connected
const int oneWireBus = 2;     // GPIO pin for DS18B20 data
const int irSensorPin = 4;   // GPIO pin for IR sensor signal
const int mq7Pin = 5;        // GPIO pin for MQ7 analog output (ADC)

// Thresholds
const float tempThreshold = 30.0;  // Temperature threshold (Celsius)
const int lightThreshold = 50;     // Light intensity threshold (lux)
const int gasThreshold = 400;      // CO concentration threshold (arbitrary value based on the sensor's output range)

// Set up the OneWire and DallasTemperature instances for DS18B20
OneWire oneWire(oneWireBus);
DallasTemperature sensors(&oneWire);

// Set up the BH1750 light sensor
BH1750 lightMeter;

// Variable to store button state
int buttonState = 0;
float temperatureC = 0.0;
uint16_t lux = 0; // Light intensity in lux
int irState = 0;  // Variable to store IR sensor state
int mq7Value = 0; // Variable to store MQ7 sensor reading (analog value)

void setup() {
  // Initialize the LED, buzzer, and button pin as output/input
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP); // Use internal pull-up resistor
  pinMode(irSensorPin, INPUT);      // Set IR sensor pin as input

  // Initialize both the LED and buzzer as OFF
  digitalWrite(ledPin, LOW);
  digitalWrite(buzzerPin, LOW);

  // Start the serial communication
  Serial.begin(115200);

  // Start the DS18B20 sensor
  sensors.begin();

  // Start the BH1750 sensor
  Wire.begin(); // Start I2C communication
  if (lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
    Serial.println(F("BH1750 started successfully"));
  } else {
    Serial.println(F("Error initializing BH1750"));
  }
}

void loop() {
  // Read the state of the button
  buttonState = digitalRead(buttonPin);

  // Read the temperature from the DS18B20 sensor
  sensors.requestTemperatures();              // Request temperature reading
  temperatureC = sensors.getTempCByIndex(0);  // Get the temperature in Celsius

  // Read the light intensity from the BH1750 sensor
  lux = lightMeter.readLightLevel();          // Get light level in lux

  // Read the state of the IR sensor
  irState = digitalRead(irSensorPin);         // HIGH when no obstacle, LOW when an obstacle is detected

  // Read the gas concentration from the MQ7 sensor (analog value)
  mq7Value = analogRead(mq7Pin);

  // Display the readings in the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.print(" °C, Light: ");
  Serial.print(lux);
  Serial.print(" lux, IR State: ");
  Serial.print(irState == LOW ? "Object detected" : "No object");
  Serial.print(", CO Level (MQ7): ");
  Serial.println(mq7Value);

  // Button logic
  if (buttonState == LOW) {
    // Turn the LED and buzzer ON if the button is pressed
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  } 
  // Temperature threshold logic
  else if (temperatureC > tempThreshold) {
    // Turn the LED and buzzer ON if temperature exceeds the threshold
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  } 
  // Light threshold logic
  else if (lux < lightThreshold) {
    // Turn the LED and buzzer ON if light intensity is below the threshold
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  } 
  // IR sensor logic
  else if (irState == LOW) {
    // Turn the LED and buzzer ON if the IR sensor detects an object
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  }
  // Gas sensor logic
  else if (mq7Value > gasThreshold) {
    // Turn the LED and buzzer ON if CO concentration exceeds the threshold
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  }
  else {
    // Turn the LED and buzzer OFF if none of the conditions are met
    digitalWrite(ledPin, LOW);
    digitalWrite(buzzerPin, LOW);
  }

  // Small delay to avoid excessive readings
  delay(500);
}