// https://forum.arduino.cc/t/delay-help-with-neopixel-strip/1414520

#include <Adafruit_NeoPixel.h>
#define LED_PIN     3
#define LED_COUNT 100
Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

#define BUTTON_PIN  2

int clickCount = 0, start, stop, added;
bool currentButtonRead, lastButtonRead, currentButtonState, done = 0;

int index;
unsigned long buttonTimer, buttonTimeout = 50;
unsigned long caseTimer, caseTimeout = 50;

int casePixels[][3] = { // [row][col = 3]
  {9, 9, 9}, // case 1 {start pixel, end pixel, added pixel}
  {8, 3, 2}, // case 2
  {29, 1, 0}, // case 3a
  {34, 37, 38}, // case 3b
  {39, 46, 47}, // casae 4a
  {48, 51, 52}, // case 4b
  {53, 61, 62}, // case 5
  {62, 34, 34}, // case 6
  {29, 1, 0} // case 7
};

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP); // configure button pin
  Serial.begin(115200); // Serial communications

  strip.begin();
  strip.setBrightness(0); // adjust brightness
  strip.clear(); // clear buffer
  strip.show(); // display buffer
  strip.setBrightness(255); // adjust brightness

  Serial.print("Click count: ");
  Serial.println(clickCount);
}

void loop() {
  showStrip(); // Adafruit_NeoPixel library calls interfere with button reading
  readButton(); // button reading routine
}

void showStrip() {
  switch (clickCount) { // count the button presses
    case 0: // starting value, clear pixels
      strip.clear();
      break;
    case 1: // light pixel 9
      lightPixels();
      // strip.setPixelColor(9, strip.Color(255, 0, 0)); // red
      break;
    case 2:
      done = 0;
      lightPixels();
      break;
    case 3: // fill pixels 34 - 38 one at a time
      lightPixels();
      break;
    case 4:
      lightPixels();
      break;
    case 5:
      lightPixels();
      break;
    case 6:
      lightPixels();
      break;
    case 7:
      lightPixels();
      break;
    default:
      break;
  }
}

void lightPixels() {
  start = casePixels[clickCount - 1][0];
  stop  = casePixels[clickCount - 1][1];
  added =  casePixels[clickCount - 1][2];

  if ((millis() - caseTimer > caseTimeout) && !done) { // next pixel lighting time

    Serial.print(start);
    Serial.print(",");
    Serial.print(stop);
    Serial.print(",");
    Serial.println(added);

    caseTimer = millis(); // reset timer
    strip.setPixelColor(start + index, strip.Color(0, 255, 0)); // green
    strip.show(); // display the pixels
    if (stop - start > 0) // increasing pixel index
      index++; // increment counter
    else if (stop - start < 0) // decreasing pixel index
      index--; // decrement counter
    if (start + index == stop) { // at end of pixel count
      index = stop;
      done = 1; // do not re-enter
    }
    strip.show();
  }
  strip.setPixelColor(added, strip.Color(255, 0, 0)); // red
  strip.show();
}

void readButton() {
  bool currentButtonRead = digitalRead(BUTTON_PIN);             // read button pin
  if (currentButtonRead != lastButtonRead) {                    // if button pin changes...
    buttonTimer = millis();                                           // ...start a timer
    lastButtonRead = currentButtonRead;                         // ... and store current state
  }
  if ((millis() - buttonTimer) > buttonTimeout) {                           // if button change was longer than debounce timeout
    if (currentButtonState == HIGH && lastButtonRead == LOW) {  // ... and State is "NOT pressed" while Button "IS PRESSED"
      digitalWrite(LED_BUILTIN, HIGH); // The button was pressed...
      clickCount++; // increment count
      if (clickCount == 8) // check clickCount
        clickCount = 0; // reset clickCount
      Serial.print("Click count: ");
      Serial.println(clickCount);
      digitalWrite(LED_BUILTIN, LOW); // "L" LED off
    }
    currentButtonState = currentButtonRead; // update button state
  }
}