#include <FastLED.h>

#define pWIDTH 5
#define pHEIGHT 8
#define NUM_LEDS ((pWIDTH) * (pHEIGHT))

extern CRGBPalette16 gCurrentGradientPalette;
extern CRGBPalette16 gTargetGradientPalette;

CRGB leds[NUM_LEDS];
bool loadingFlag = true;

void drawPixelXY(int8_t x, int8_t y, CRGB color) {
  if (leds == nullptr) return;
  if (x < 0 || x > pWIDTH - 1 || y < 0 || y > pHEIGHT - 1) return;
  int16_t thisPixel = getPixelNumber(x, y);
  if (thisPixel >= 0 && thisPixel < NUM_LEDS) leds[thisPixel] = color;
}

uint16_t getPixelNumber(uint8_t x, uint8_t y) {
  if (x >= pWIDTH || y >= pHEIGHT)
    return NUM_LEDS-1;
  if (y & 1)
    x = pWIDTH - 1 - x;
   return x + (y * pWIDTH);
}

uint32_t getPixColor(int16_t thisPixel) {
  if (leds == nullptr) return 0;
  if (thisPixel < 0 || thisPixel > NUM_LEDS - 1) return 0;
  return (((uint32_t)leds[thisPixel].r << 16) | ((uint32_t)leds[thisPixel].g << 8 ) | (uint32_t)leds[thisPixel].b);
}

uint32_t getPixColorXY(int8_t x, int8_t y) {
  return getPixColor(getPixelNumber(x, y));
}

uint16_t XY(uint8_t x, uint8_t y) {
  int16_t idx = getPixelNumber(x, y);
  if (idx >= 0 && idx < NUM_LEDS) return idx;
}

void shiftDown() {
  for (uint8_t x = 0; x < pWIDTH; x++) {
    for (uint8_t y = 0; y < pHEIGHT - 1; y++) {
      drawPixelXY(x, y, getPixColorXY(x, y - (y>0)?1:0));
    }
  }
}

void shiftUp() {
  for (uint8_t x = 0; x < pWIDTH; x++) {
    for (uint8_t y = pHEIGHT - 1; y > 0; y--) {
      drawPixelXY(x, y, getPixColorXY(x, y - 1));
    }
  }
}

void setup() {
  FastLED.addLeds<WS2812B, 3, GRB>(leds, NUM_LEDS);
}

void loop() {
    if (loadingFlag) {
    loadingFlag = false;
    FastLED.clear();
  }
  draw();
  FastLED.delay(120);
}


void draw() {
  
  static uint8_t step=0, row=0, col=0;
  static bool dir=true;

  //fadeToBlackBy(leds, NUM_LEDS, 16);
  shiftUp();

  if (step==0){
    for(uint8_t x=0; x<pWIDTH; x++){
      if(x==col) drawPixelXY(x, 0, CHSV(48, 255, 255));
      else drawPixelXY(x, 0, CHSV(0, 0, 0));
      // if (row>0) drawPixelXY(x, row-1, CHSV(0, 0, 0));
      // if (row==0) drawPixelXY(x, pHEIGHT-1, CHSV(0, 0, 0));
    }
  }
  
  if (++step>1) {
    step=0;
    if (++row>pHEIGHT) row=0;
    if (col<pWIDTH-1&&dir) {
      col++;
      if (col==pWIDTH-1) dir = false;
    }
    else {
      col--;
      if (col==0) dir = true;
    }
  }

  // EVERY_N_MILLISECONDS(20) {hue++;}
  // EVERY_N_SECONDS(10) {chooseNextPalette();}
  // EVERY_N_MILLISECONDS(12) nblendPaletteTowardPalette( gCurrentGradientPalette, gTargetGradientPalette, 12);

}