#include <LiquidCrystal_I2C.h>

// LCD panel
#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

// Gomb
#define BUTTON_PIN  12
unsigned long TIME_START;  //Lenyomás kezdete
unsigned long TIME_END;    //Lenyomás vége
unsigned long TIME_VALUE;  // eltelt idő
unsigned long STATE_START; // 
int lastState = HIGH;
int value;

// Led RED
#define LED_R 8

// Photo resistor
#define PR_VCC 7
#define PR_DO 2
unsigned long TIME_START_PR; //Mérés kezdete
unsigned long TIME_END_PR;   //Mérés vége
float TIME_VALUE_PR;        //Eltelt idő
unsigned long STATE_START_PR; 
unsigned long LAST_STATE_START_PR;
int lastState_PR =  LOW;
int value_PR = digitalRead(PR_DO);
int PR_VCC_State = HIGH;

int EZER;
float HANYAD;

// Függvények
void isr_PR(void);


void setup() {
  // Init
  lcd.init();
  lcd.backlight();
  
  Serial.begin(115200);
  
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  digitalWrite(BUTTON_PIN, HIGH);

  pinMode(PR_VCC, OUTPUT);
  digitalWrite(PR_VCC, HIGH);

  pinMode(PR_DO, INPUT_PULLUP);
  digitalWrite(PR_DO, LOW);

  attachInterrupt(digitalPinToInterrupt(2), isr_PR, CHANGE);

  TIME_START = millis();
  
}

void loop() {
  // Nyomogomb 
  value = digitalRead((BUTTON_PIN));
  if (lastState != value and millis() >= STATE_START + 3)  {
    lastState = value;
    if (value == HIGH) {
      // RELEASED
      STATE_START = millis();
      TIME_END = millis();
      TIME_VALUE = TIME_END - TIME_START;      
      HANYAD = TIME_VALUE;
      int H = 1/(HANYAD/10000); 
      Serial.print(" released :");
      Serial.println(TIME_VALUE);
      Serial.print("1/");
      Serial.println(H);
      digitalWrite(LED_R, LOW);
      digitalWrite(PR_VCC, PR_VCC_State );
    }
    if (value == LOW) {
      // PRESSED
      STATE_START = millis();
      TIME_START = millis();
      Serial.println(" pressed");
      digitalWrite(LED_R, HIGH);
      PR_VCC_State = !PR_VCC_State;
    }
}
// Érzékelő
  value_PR = digitalRead(PR_DO);
  if (lastState_PR != value_PR)  {
    lastState_PR = value_PR;
    if (value_PR == HIGH) {
      Serial.print(" NO LIGHT :");
      TIME_VALUE_PR = TIME_END_PR - TIME_START_PR;
      Serial.println(TIME_VALUE_PR);
      EZER=(TIME_VALUE_PR/1000);

      lcd.setCursor(0, 0);
      lcd.print("                ");      
      if (EZER > 0) {
        Serial.print(EZER);
        Serial.print(" + 1/");
        Serial.println(float((1/TIME_VALUE_PR)*1000)); 
        lcd.setCursor(0, 0);
        lcd.print(EZER);
        lcd.print(" + 1/");        
        lcd.print(float((1/TIME_VALUE_PR-(EZER*1000))*1000));
      }
      else {
        Serial.print("   1/");
        Serial.println(float((1/TIME_VALUE_PR)*1000));
        lcd.setCursor(3, 0);
        lcd.print(" 1/");
        lcd.print(float((1/TIME_VALUE_PR)*1000));   
      }
    } 
    else {
      Serial.println(" LIGHT ");
    }
  }
}

void isr_PR(void) {

if (digitalRead(PR_DO) == HIGH) {
      STATE_START_PR = millis();
      TIME_END_PR = millis();
}
else {
  if (digitalRead(PR_DO) == LOW) {
  STATE_START_PR = millis();
  TIME_START_PR = millis();
  }
}
}