//How to control groups of leds in FastLed Library with Arduino and WS2812B - Tips & Tricks FastLed Library - by Fedaceag Ionut ( Youtube - Think small, build big! )
#include <FastLED.h>            // FastLed library version 3.2.1 - https://github.com/FastLED/FastLED/wiki/Overview or http://fastled.io/ with NEOPIXEL or WS2812B
#define LED_TYPE  WS2812B       // define the led type
#define NUM_STRIPS 1            // number of led strips
#define NUM_LEDS_PER_STRIP 50   // total number of leds per strip
CRGB leds[NUM_STRIPS][NUM_LEDS_PER_STRIP];

const int btn1 = 2;
const int btn2 = 3;
const int btn3 = 4;
const int btn4 = 5;

const int pot1 = A0;
const int pot2 = A1;

int btn1Val = 1;
int btn2Val = 1;
int btn3Val = 1;
int btn4Val = 1;

int pot1Val = 0;
int pot2Val = 0;

int signalState = 0;
int signalAnim = 2;
int delaySignalAnim = 1;
int delaySignalOff = 250;
unsigned long currentMillis = 0; 
unsigned long previousMillis = 0;

void setup() {
  Serial.begin(115200);
  
  pinMode(btn1, INPUT);
  pinMode(btn2, INPUT);
  pinMode(btn3, INPUT);
  pinMode(btn4, INPUT);
  
  pinMode(pot1, INPUT);
  pinMode(pot2, INPUT);

  FastLED.addLeds<NEOPIXEL, 12>(leds[0], NUM_LEDS_PER_STRIP); //define the pin output for led strip one

  fill_solid(leds[0], NUM_LEDS_PER_STRIP, CRGB::Black); // some led strips are all on at power on, so let's power them off at boot
  FastLED.show();
}

void loop() {
  btn1Val = digitalRead(btn1);
  btn2Val = digitalRead(btn2);
  btn3Val = digitalRead(btn3);
  btn4Val = digitalRead(btn4);
  
  pot1Val = analogRead(pot1);
  pot2Val = analogRead(pot2);


  //grouping leds with for loop
  if(btn1Val == 1){
    for(int pixel = 4; pixel < 45; pixel++) { 
      leds[0][pixel] = CHSV( 0, 255, 255);
    }
  }

  //grouping leds with fill_gradient
  if(btn2Val == 1){
    fill_gradient(leds[0],14,CHSV( 96, 255, 150),44,CHSV( 96, 255, 150));
  }
  
  //grouping leds with fill_gradient and changing start and end position with potentiometer
  if(btn3Val == 1){
    pot1Val = map(pot1Val,0,1023,0,NUM_LEDS_PER_STRIP);
    pot2Val = map(pot2Val,0,1023,0,NUM_LEDS_PER_STRIP); //comment this line for microphone/music test
    //pot2Val = constrain(pot2Val,0,150); //uncomment this line for microphone/music test
    //Serial.println(pot2Val); //uncomment this line for microphone/music test
    //pot2Val = map(pot2Val,0,150,0,NUM_LEDS_PER_STRIP); //uncomment this line for microphone/music test
    
    fill_gradient(leds[0],pot1Val,CHSV(160, 255, 150),pot2Val,CHSV( 160, 255, 150));
  }

  //signal made with fill_gradient
  if(btn4Val == 1 || signalState != 0){

    for(int endSignal = 0; endSignal < NUM_LEDS_PER_STRIP; endSignal++){
      fill_gradient(leds[0],0,CHSV( 40, 255, 150),endSignal,CHSV( 40, 255, 150));
      
      currentMillis = previousMillis = millis();
      while(previousMillis + delaySignalAnim >= currentMillis){
        FastLED.show();
        currentMillis = millis();
      }
    }

    currentMillis = previousMillis = millis();
    while(previousMillis + delaySignalOff >= currentMillis){
      FastLED.show();
      currentMillis = millis();
    }
    
    fill_solid(leds[0], NUM_LEDS_PER_STRIP, CRGB::Black);
    
    currentMillis = previousMillis = millis();
    while(previousMillis + delaySignalOff >= currentMillis){
      FastLED.show();
      currentMillis = millis();
    }

    signalState++;
    if(signalState == signalAnim){
      signalState = 0;
    }
    
  }

  if(btn1Val == 0 && btn2Val == 0 && btn4Val == 0 && signalState == 0){ //except btn3Val
    fadeToBlackBy( leds[0], NUM_LEDS_PER_STRIP,50);
  }
  
  FastLED.show();
}