#include <EEPROM.h>

#define pinMessung 3
#define pinLED 4
#define internADW A0  //interner AD-Wandler

#define luxMIN  0
#define luxMAX 20000
#define adcMax 1023
#define eeAdresse 0

float adcWert = 0;
float luxWert = 0;
float luxTMP = 0;   // Temporary
float luxAVG = 0;

int g;     // Grenzwert


// Source: https://forum.arduino.cc/t/clearing-serial-buffer-solved/227853
void clearSerialBuffer() {
  while (Serial.available() > 0) {
    Serial.read(); // Read and discard each byte
  }
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(pinMessung, INPUT_PULLUP);
  //pinMode(internADW, INPUT);
  pinMode(pinLED, OUTPUT);
  EEPROM.get(eeAdresse, g);

  // nur fuer den allerersten Durchlauf
  if (g >= 0 && g <= 20000){}
  else
  {
    g = 10001;
    EEPROM.put(eeAdresse, g);
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  if(digitalRead(pinMessung) == LOW)
  {
    for(int i = 0; i < 10; i++)
    {
      adcWert = analogRead(internADW);
      luxWert = luxMAX / adcMax * adcWert;
      luxTMP = luxTMP + luxWert;
      delay(500);
    }
    luxAVG = luxTMP / 10;
    luxTMP = 0;
    if(luxAVG > g)
    {
      digitalWrite(pinLED, HIGH);
      Serial.print("Mittelwert: ");
      Serial.println(luxAVG);
      Serial.print("Grenzwert ueberschriettet: ");
      Serial.println(g);
    }
    else
    {
      digitalWrite(pinLED, LOW);
      Serial.print("Mittelwert: ");
      Serial.println(luxAVG);
      Serial.print("Grenzwert: ");
      Serial.println(g);
    }
  }
  else
  {
    digitalWrite(pinLED, LOW);
  }
  if (Serial.available() > 0)
  {
    int wert = Serial.parseInt();
    if(wert >= 0 && wert <= 20000)
    {
      g = wert;
      EEPROM.put(eeAdresse, g);
      Serial.print("Grenzwert aktualisiert auf: "); 
      Serial.println(g);
      clearSerialBuffer();
    }
    else
    {
      Serial.println("Grenzwertbereich muss von 0 bis 20000 sein!");
      clearSerialBuffer();
    }
  }
}