#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2

#define BUTTON_PIN  12
#define LED_R 8
#define IR_VCC 7
#define IR_DO 4

unsigned long TIME_START;
unsigned long TIME_END;
unsigned long TIME_VALUE;
unsigned long STATE_START;

unsigned long TIME_START_IR;
unsigned long TIME_END_IR;
float TIME_VALUE_IR;
unsigned long STATE_START_IR;

int EZER;
int lastState = HIGH;
int lastState_IR =  LOW;

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);


void setup() {
  // Init
  lcd.init();
  lcd.backlight();

  Serial.begin(115200);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(IR_VCC, OUTPUT);
  pinMode(IR_DO, INPUT);
  TIME_START = millis();
  digitalWrite(IR_VCC, HIGH);
  digitalWrite(IR_DO, LOW);
}



void loop() {
  int value = digitalRead((BUTTON_PIN));
  if (lastState != value and millis() >= STATE_START+5)  {
    lastState = value;
    if (value == HIGH) {
      STATE_START = millis();
      TIME_END = millis();
      Serial.print(" released :");
      TIME_VALUE = TIME_END-TIME_START;
      Serial.println(TIME_VALUE);
      digitalWrite(LED_R, LOW);
    }
    if (value == LOW) {
      STATE_START = millis();
      TIME_START = millis();
      Serial.println(" pressed");
      digitalWrite(LED_R, HIGH);
    }
}
int value_IR = digitalRead((IR_DO));
  if (lastState_IR != value_IR)  {
    lastState_IR = value_IR;
    if (value_IR == HIGH) {
      STATE_START_IR = millis();
      TIME_END_IR = millis();
      Serial.print(" NO LIGHT :");
      TIME_VALUE_IR = TIME_END_IR-TIME_START_IR;
      Serial.println(TIME_VALUE_IR);
      EZER=int (TIME_VALUE_IR/1000);
      Serial.print(EZER);
      Serial.print(" 1/");
      lcd.setCursor(0, 0);
      lcd.print("                ");      
      if (EZER > 0) {
        lcd.setCursor(0, 0);
        lcd.print(EZER);
        lcd.print(" + 1/");
        Serial.println(int (10000/(TIME_VALUE_IR - EZER * 1000)));  
        lcd.print(int (10000/(TIME_VALUE_IR - EZER * 1000)));
      }
      else {
        lcd.setCursor(3, 0);
        lcd.print(" 1/");
        Serial.println(int (10000/TIME_VALUE_IR));
        lcd.print(int (10000/TIME_VALUE_IR));     
      }      
    }
    if (value_IR == LOW) {
      STATE_START_IR = millis();
      TIME_START_IR = millis();
      Serial.println(" LIGHT ");      
    }  
  }
}