/*
  Forum: https://forum.arduino.cc/t/oled-rotary-encoder/1175366
  Wokwi: https://wokwi.com/projects/377762218537644033
*/

//Screen
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

//Rotary Encoder

// Rotary Encoder Inputs
#define inputCLK 4
#define inputDT 5

String encdir = "";  //String to be populated with either ClockWise or CounterClockWise

//Variables
int Length    = 20;
int oldLength = 0;

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

void setup() {
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();

  //RotaryEncoder
  // Set encoder pins as inputs
  pinMode(inputCLK, INPUT);
  pinMode(inputDT, INPUT);

}

void loop() {
  readEncoder();
  printToDisplay();
}

void readEncoder() {
  static int previousStateCLK = HIGH;  // Store the previous state for the next call of readEncoder()
  //Rotary Encoder
  // Read the current state of inputCLK
  int currentStateCLK = digitalRead(inputCLK);
  // If the previous and the current state of the inputCLK are different then a pulse has occured
  if (currentStateCLK != previousStateCLK) {
    int dtValue = digitalRead(inputDT);
    if (currentStateCLK == LOW && dtValue == HIGH) {
      // Encoder is rotating clockwise
      Length++;
    }
    if (currentStateCLK == LOW && dtValue == LOW) {
      // Encoder is rotating counterclockwise
      Length--;
      if (Length < 0) {
        Length = 0;
      }
    };
  }
  // Update previousStateCLK with the current state
  previousStateCLK = currentStateCLK;
}

void printToDisplay() {
  if (Length != oldLength) {
    //Oled
    oldLength = Length;
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(WHITE);
    //Timer
    display.setCursor(0, 10);
    display.print("Timer - ");
    display.print(Length);
    display.println(" Minutes");
    display.display();
  }
}