#include <FastLED.h>

#define NUM_LEDS 50
#define DATA_PIN 4
#define INTR_PIN 2
#define VIZUALIZATIONS 2

CRGB pixels[NUM_LEDS];
unsigned char offset = 0;
void (*viz[VIZUALIZATIONS])(unsigned char);
volatile unsigned char currentViz = 0;

void viz1(unsigned char offset) {
  for (unsigned char i = 0; i < NUM_LEDS; i++)
    pixels[(i + offset) % NUM_LEDS] = CRGB(128 + floor(127 * sin(2 * 3.1415926 * i / NUM_LEDS)), 0, 0);
}
void viz2(unsigned char offset) {
  for (unsigned char i = 0; i < NUM_LEDS; i++)
    pixels[i] = 0;
  pixels[offset % NUM_LEDS]        = CRGB(0x0F, 0xF, 0xF);
  pixels[(offset + 1) % NUM_LEDS]  = CRGB(0x1F, 0xE, 0xE);
  pixels[(offset + 2) % NUM_LEDS]  = CRGB(0x2F, 0xD, 0xD);
  pixels[(offset + 3) % NUM_LEDS]  = CRGB(0x3F, 0xC, 0xC);
  pixels[(offset + 4) % NUM_LEDS]  = CRGB(0x4F, 0xB, 0xB);
  pixels[(offset + 5) % NUM_LEDS]  = CRGB(0x5F, 0xA, 0xA);
  pixels[(offset + 6) % NUM_LEDS]  = CRGB(0x6F, 0x9, 0x9);
  pixels[(offset + 7) % NUM_LEDS]  = CRGB(0x7F, 0x8, 0x8);
  pixels[(offset + 8) % NUM_LEDS]  = CRGB(0x8F, 0x7, 0x7);
  pixels[(offset + 9) % NUM_LEDS]  = CRGB(0x9F, 0x6, 0x6);
  pixels[(offset + 10) % NUM_LEDS] = CRGB(0xAF, 0x5, 0x5);
  pixels[(offset + 11) % NUM_LEDS] = CRGB(0xBF, 0x4, 0x4);
  pixels[(offset + 12) % NUM_LEDS] = CRGB(0xCF, 0x3, 0x3);
  pixels[(offset + 13) % NUM_LEDS] = CRGB(0xDF, 0x2, 0x2);
  pixels[(offset + 14) % NUM_LEDS] = CRGB(0xEF, 0x1, 0x1);
  pixels[(offset + 15) % NUM_LEDS] = CRGB(0xFF, 0x0, 0x0);
}

void changeViz(void) {
  currentViz = (currentViz + 1) % VIZUALIZATIONS;
}

void setup() {
  FastLED.addLeds<WS2812B, DATA_PIN>(pixels, NUM_LEDS);
  FastLED.setBrightness(255);
  for (int i = 0; i < NUM_LEDS; i++)
    pixels[i] = CRGB(0, 0, 0);
  FastLED.show();
  viz[0] = &viz1;
  viz[1] = &viz2;
  pinMode(INTR_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(INTR_PIN), changeViz, FALLING);
}

void loop() {
  (*viz[currentViz])(offset);
  FastLED.show();
  delay(100);
  offset++;
}