// Program for attiny3216 to respons the rotary encode for menu navigation
// created by Jans Hendry
// Universitas Gadjah Mada, Indonesia
// Kamakura Node, Japan
// fab academy MIT - 2022
// This program still have many aspect to improve. Please do...

// the directives/predecessor
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// create lcd as an object
// format: address, num of columns, num of rows
LiquidCrystal_I2C lcd(0x27, 20, 4);

// create costum character on LCD
byte ch0[8] = {
  0b00001,
  0b00011,
  0b00111,
  0b11111,
  0b11111,
  0b00111,
  0b00011,
  0b00001
};

// variables
const int sw = 4; // sw pin
const int dt = 3; // dt pin
const int clk = 7; // clk pin
int inc = 0, oldState, newState, dta;
int pos;

void setup() {
  Serial.begin(9600); // start serial

  // begin lcd
  lcd.begin(20, 4);

  // setting up
  lcd.init();

  // turn on backlight <- the variable resistor has been adjusted
  lcd.backlight();

  // clear screen
  lcd.clear();

  // create costum character
  lcd.createChar(8, ch0); // arrow

  // pin mode
  pinMode(sw, INPUT_PULLUP);
  pinMode(dt, INPUT_PULLUP);
  pinMode(clk, INPUT_PULLUP);
  oldState = digitalRead(clk);

  // static text
  defDisplay();

  lcd.setCursor(19, 0);
  lcd.write((byte)8);

  delay(500); // take a breath
}

void loop() {
  // check current state
  newState = digitalRead(clk);
  // conditional IF
  if (newState != oldState)
  {
    dta = digitalRead(dt);
    if (dta != newState)
    {
      inc++;
    }
    else {
      inc--;
    }

    // check max increment
    if (inc >= 6) {
      inc = 6;
    }
    // check min decrement
    if ((inc <= 0) && (inc >= -6)){
      inc = -1 * inc;
    }
    // display arrow
    clearAnc(); // clear arrow
    if (inc % 2 == 0) {
      pos = inc / 2;
      lcd.setCursor(19, pos);
      lcd.write((byte)8);
    }
    else if (inc % 2 != 0) {
      pos = (inc - 1) / 2;
      lcd.setCursor(19, pos);
      lcd.write((byte)8);
    }
    else {
      pos = 0;
      lcd.setCursor(19, pos);
      lcd.write((byte)8);
    }
  }

  if (digitalRead(sw) == LOW) {
    lcd.clear();
    lcd.setCursor(4, 1);
    lcd.print("DEMO MENU ");
    lcd.setCursor(15, 1);
    lcd.print(pos + 1);
    delay(3000);
    defDisplay();
    lcd.setCursor(19, pos);
    lcd.write((byte)8);
  }
  oldState = newState; // update previous state
}

void defDisplay() {
  lcd.clear(); // clear display

  lcd.setCursor(0, 0);
  lcd.print("DEMO MENU 1");

  lcd.setCursor(0, 1);
  lcd.print("DEMO MENU 2");

  lcd.setCursor(0, 2);
  lcd.print("DEMO MENU 3");

  lcd.setCursor(0, 3);
  lcd.print("DEMO MENU 4");
}

void clearAnc() {
  for (int i = 0; i < 4; i++) {
    lcd.setCursor(19, i);
    lcd.print(" ");
  }
}