// Copied from https://wokwi.com/projects/353963309327616001
//
// Changes:
//  1. millis() needs "unsigned long" variables.
//  2. Changed variable names of "t1" and "t1_prev".
//  3. Moved the rpm calculation to the main section of the loop().
//  4. There is no need to use "String", so I replaced those.
//  5. Printing the encoder counter is now after increment or decrement.
//  6. After thinking very hard, I think multiply by 3 is okay.
//
// Notes:
//  I don't have a rotary encoder, does 20 steps mean that both the CLK and DT 
//  have a ring with 10 teeth ?
//  I think that "pulse_cnt * 3" is good.
//  Do you see how coarse the rpm value changes ? When displaying a low rpm very often, 
//  it is better to calculate the time between the pulses.
//  If you add more code to the sketch, then you might need to start using interrupts. 
//  The Encoder library is super extra optimized: 
//    https://www.pjrc.com/teensy/td_libs_Encoder.html
//


#define ENCODER_CLK 2
#define ENCODER_DT  3

// define the pins for the RGB LED
#define LED_RED_PIN 9
#define LED_GREEN_PIN 10
#define LED_BLUE_PIN 11

int lastClk = HIGH;
int pulse_cnt = 0;
unsigned long previousMillis = 0;
unsigned long previousPulseMillis = 0;


void setup() {
  Serial.begin(115200);
  pinMode(ENCODER_CLK, INPUT);
  pinMode(ENCODER_DT, INPUT);

  // set the pins for the RGB LED as outputs
  pinMode(LED_RED_PIN, OUTPUT);
  pinMode(LED_GREEN_PIN, OUTPUT);
  pinMode(LED_BLUE_PIN, OUTPUT);
}

void loop() {
  unsigned long currentMillis = millis();

  int newClk = digitalRead(ENCODER_CLK);
  if (newClk != lastClk) {
    // There was a change on the CLK pin
    lastClk = newClk;
    //add to rmp count
    pulse_cnt++;
  }

  // Calculate speed by counting the pulses during a second
  if (currentMillis-previousMillis >= 1000) {
    // After counting the pulses we have to calculate the speed(revolutions per minute),
    // by knowing that KY-040 Rotary Encoder module has 20 steps per revolution.
    // We derive the equation: RPM =(counts_second / 20)* 60s = counts_second * 3
    int RPM = pulse_cnt * 3;
    previousMillis = currentMillis;
    pulse_cnt = 0;

    Serial.print("RPM = ");
    Serial.println(RPM);


    if(RPM < 10){
      //turn LED red
      Serial.print("Speed Up");
      setColor(255, 0, 0);
    }
    else if(RPM > 25){
      //turn LED blue
      Serial.print("Slow Down");
      analogWrite(LED_RED_PIN, 0);
      analogWrite(LED_GREEN_PIN, 0);
      analogWrite(LED_BLUE_PIN, 255);
    }
    else{
      //turn LED green
      Serial.print("All Good");
      analogWrite(LED_RED_PIN, 0);
      analogWrite(LED_GREEN_PIN, 255);
      analogWrite(LED_BLUE_PIN, 0);
    }
    Serial.print("\n");
  }
}

void setColor(int red, int green, int blue)
{
  analogWrite(LED_RED_PIN, 255-red);
  analogWrite(LED_GREEN_PIN, 255-green);
  analogWrite(LED_BLUE_PIN, 255-blue);
}