#include <JC_Button.h> // https://github.com/JChristensen/JC_Button

struct button_t
{
  const Button jc_button;
  const uint16_t period;
  const uint8_t power;
};

const button_t buttons[] =
{
  { Button( 4 ), 1000, 10 },
  { Button( 5 ), 2000, 20 },
};

const uint8_t buttonsCount = sizeof( buttons ) / sizeof( button_t );


enum State : uint8_t
{
  Initialize,
  SelectPeriod,
  SelectPower,

  Invalid,
};


void setup()
{
  pinMode( LED_BUILTIN, OUTPUT );
  Serial.begin( 115200 );

  for ( uint8_t i = 0; i < buttonsCount; i++ )
  {
    buttons[i].jc_button.begin();
  }
}


void loop()
{
  static uint8_t state = State::Initialize;
  static uint8_t state_previous = State::Invalid;
  static uint32_t timer_start = 0;
  static uint32_t timer_duration = 0;
  button_t * button;

  for ( uint8_t i = 0; i < buttonsCount; i++ )
  {
    button = &buttons[i];
    button->jc_button.read();
    
    if ( button->jc_button.wasReleased() )
    {
      state++;
      break;
    }
  }

  if ( state_previous != state )
  {
    state_previous = state;

    static uint32_t period;
    static uint32_t power;

    switch ( state )
    {
      case State::Initialize :
      {
        timer_duration = 0;
        digitalWrite( LED_BUILTIN, LOW );

        Serial.print( "Choose period : " );
        break;
      }

      case State::SelectPeriod :
      {
        period = button->period;
        Serial.println( period );

        Serial.print( "Choose power : " );
        break;
      }

      case State::SelectPower :
      {
        power = button->power;
        Serial.println( power );

        timer_start = millis();
        timer_duration = period * power / 100UL;
        digitalWrite( LED_BUILTIN, HIGH );

        Serial.print( "LED on for " );
        Serial.print( timer_duration );
        Serial.println( " ms..." );
        break;
      }

      default :
      {
        state = State::Initialize;
        Serial.println( "Reset" );
        break;
      }
    }
  }

  if ( timer_duration > 0 )
  {
    if ( millis() - timer_start >= timer_duration )
    {
      state = State::Initialize;
      Serial.println( "Done" );
    }
  }
}