// https://forum.arduino.cc/t/msp430f5529lp-double-click/1136526/2
// https://wokwi.com/projects/367172147215229953

// pins
#define RED_LED 5 // LED pin
#define GREEN_LED 3 // LED pin
#define buttonPin2 4
#define buttonPin4 2

// pushbuttons
int buttonPressLeft = 0;
int buttonPressRight = 0;

// states
bool RED_LED_state = HIGH;
bool GREEN_LED_state = HIGH;

// interval timers
int PERIOD = 500; // initial interval
int RED_LED_period = PERIOD;
int GREEN_LED_period = PERIOD;

// event timers
unsigned long RED_LED_previous_time = 0;
unsigned long GREEN_LED_previous_time = 0;

unsigned long currentMillis();

void setup() {
  Serial.begin(115200);
  welcome();

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);

  pinMode(buttonPin2, INPUT_PULLUP);
  pinMode(buttonPin4, INPUT_PULLUP);
}

void loop() {

  unsigned long currentTime = millis();  // start main timer

  buttonPressRight = digitalRead(buttonPin2);
  buttonPressLeft = digitalRead(buttonPin4);

  if ( currentTime - RED_LED_previous_time >= RED_LED_period ) {  // check event timer
    RED_LED_state = !RED_LED_state; // change LED state
    digitalWrite(RED_LED, RED_LED_state); // write to LED pin
    RED_LED_previous_time = currentTime;    //update new start timer
  }

  if ( currentTime - GREEN_LED_previous_time >= GREEN_LED_period ) {  // check event timer
    GREEN_LED_state = !GREEN_LED_state; // change LED state
    digitalWrite(GREEN_LED, GREEN_LED_state); // write to LED pin
    GREEN_LED_previous_time = currentTime;    //update new start timer
  }

  if (!buttonPressRight) {
    delay(150); // debounce the button
    GREEN_LED_period = GREEN_LED_period - 50;
    if (GREEN_LED_period > 199) {
      Serial.print("RED ");
      Serial.print(RED_LED_period);
      Serial.print(" GREEN ");
      Serial.println(GREEN_LED_period);
    }
    else {
      GREEN_LED_period = PERIOD;
      Serial.print("RED ");
      Serial.print(RED_LED_period);
      Serial.print(" GREEN ");
      Serial.println(GREEN_LED_period);
    }
  }

  if (!buttonPressLeft) {
    delay(150); // debounce the button
    RED_LED_period = RED_LED_period - 50;
    if (RED_LED_period > 199) {
      Serial.print("RED ");
      Serial.print(RED_LED_period);
      Serial.print(" GREEN ");
      Serial.println(GREEN_LED_period);
    }
    else {
      RED_LED_period = PERIOD;
      Serial.print("RED ");
      Serial.print(RED_LED_period);
      Serial.print(" GREEN ");
      Serial.println(GREEN_LED_period);
    }
  }
}

void welcome() {
  Serial.print("Frequency for each LED starts at ");
  Serial.print(PERIOD);
  Serial.println("ms.");
  Serial.println("Pressing either button reduces the LED frequency by 50ms.");
  Serial.print("Reducing either LED frequency below 200ms resets frequency to ");
  Serial.print(PERIOD);
  Serial.println("ms.\n");
  Serial.print("RED ");
  Serial.print(RED_LED_period);
  Serial.print(" GREEN ");
  Serial.println(GREEN_LED_period);
}