const int POT_PIN = A2;
const int LDR_PIN = A1;
const int THERMISTOR_PIN = A0;
const int BUZZER_PIN = 8;
const int ALARM_LED_PIN = 13;

const float VOLTAGE_MIN = 1.0;
const float VOLTAGE_MAX = 4.0;
const int LIGHT_MIN = 200;
const int LIGHT_MAX = 800;
const float TEMP_MIN = 10.0;
const float TEMP_MAX = 35.0;

const int BUFFER_SIZE = 100;
float voltageHistory[BUFFER_SIZE];
int lightHistory[BUFFER_SIZE];
float tempHistory[BUFFER_SIZE];
int bufferIndex = 0;
bool bufferFull = false;

const unsigned long MEASURE_INTERVAL = 500;
unsigned long lastMeasureTime = 0;

const int NUM_READINGS = 10;
int voltageReadings[NUM_READINGS] = {0};
int voltageReadIndex = 0;
int voltageTotal = 0;

void setup() {
  pinMode(ALARM_LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  
  for (int i = 0; i < NUM_READINGS; i++) {
    voltageReadings[i] = analogRead(POT_PIN);
    voltageTotal += voltageReadings[i];
  }
}

void loop() {
  unsigned long currentTime = millis();
  
  if (currentTime - lastMeasureTime >= MEASURE_INTERVAL) {
    lastMeasureTime = currentTime;
    
    float voltage = readVoltage();
    int lightLevel = readLightLevel();
    float temperature = readTemperature();
    
    saveToHistory(voltage, lightLevel, temperature);
    
    bool alarm = checkAlarm(voltage, lightLevel, temperature);
    
    handleAlarm(alarm);
  }
}

float readVoltage() {
  voltageTotal -= voltageReadings[voltageReadIndex];
  voltageReadings[voltageReadIndex] = analogRead(POT_PIN);
  voltageTotal += voltageReadings[voltageReadIndex];
  voltageReadIndex = (voltageReadIndex + 1) % NUM_READINGS;
  
  int average = voltageTotal / NUM_READINGS;
  float voltage = average * (5.0 / 1023.0);
  
  return voltage;
}

int readLightLevel() {
  return analogRead(LDR_PIN);
}

float readTemperature() {
  int raw = analogRead(THERMISTOR_PIN);
  float voltage = raw * (5.0 / 1023.0);
  float tempC = (voltage - 0.5) * 100.0;
  return tempC;
}

void saveToHistory(float voltage, int light, float temp) {
  voltageHistory[bufferIndex] = voltage;
  lightHistory[bufferIndex] = light;
  tempHistory[bufferIndex] = temp;
  
  bufferIndex = (bufferIndex + 1) % BUFFER_SIZE;
  
  if (bufferIndex == 0) {
    bufferFull = true;
  }
}

bool checkAlarm(float voltage, int light, float temp) {
  bool voltageAlarm = (voltage < VOLTAGE_MIN || voltage > VOLTAGE_MAX);
  bool lightAlarm = (light < LIGHT_MIN || light > LIGHT_MAX);
  bool tempAlarm = (temp < TEMP_MIN || temp > TEMP_MAX);
  
  return voltageAlarm || lightAlarm || tempAlarm;
}

void handleAlarm(bool alarm) {
  if (alarm) {
    digitalWrite(ALARM_LED_PIN, HIGH);
    tone(BUZZER_PIN, 1000, 200);
  } else {
    digitalWrite(ALARM_LED_PIN, LOW);
  }
}