#include "FastLED.h"

#define NUM_LEDS     100
#define LED_DATA_PIN 3
#define BRIGHTNESS   255      // low brightness for stability
#define DELAY_MS     50      // controls speed of the wave
#define TAIL_LENGTH  10      // length of the fading tail

CRGB leds[NUM_LEDS];

void setup() {
    FastLED.addLeds<WS2812B, LED_DATA_PIN, GRB>(leds, NUM_LEDS);
    FastLED.setBrightness(BRIGHTNESS);
    fill_solid(leds, NUM_LEDS, CRGB::Black);
    FastLED.show();
}

void loop() {
    for (int head = 0; head < NUM_LEDS + TAIL_LENGTH; head++) {
        // First, fade all LEDs slightly to create a tail effect
        for (int i = 0; i < NUM_LEDS; i++) {
            leds[i].nscale8(200); // 200/255 ≈ 78% brightness remaining
        }

        // Light up the head LED in full red
        if (head < NUM_LEDS) {
            leds[head] = CRGB::Red;
        }

        FastLED.show();
        delay(DELAY_MS);
    }
}