#include <EEPROM.h>

int leds[16] = {2,3,4,5,6,7,8,9,10,11,12,13,A0,A1,A2,A3};

#define BTN_PIN A4     // Digital button to go next pattern + auto save
#define SPEED_PIN A5   // Speed control pot

int pattern = 0;
bool lastBtn = HIGH;

void setup() {
  for (int i = 0; i < 16; i++) pinMode(leds[i], OUTPUT);

  pinMode(BTN_PIN, INPUT_PULLUP);

  // Load last saved pattern
  pattern = EEPROM.read(0);
  if (pattern > 5) pattern = 0;
}

void loop() {

  int speedVal = analogRead(SPEED_PIN);
  int delayTime = map(speedVal, 0, 1023, 20, 400);

  // ---- NEXT PATTERN ON BUTTON PRESS ----
  bool btn = digitalRead(BTN_PIN);

  if (btn == LOW && lastBtn == HIGH) {   // Detect falling edge
    pattern++;
    if (pattern > 5) pattern = 0;

    EEPROM.write(0, pattern);            // Auto save
    delay(250);                          // Debounce
  }
  lastBtn = btn;

  // ---- RUN SELECTED PATTERN ----
  switch (pattern) {
    case 0: pattern_normal(delayTime); break;
    case 1: pattern_reverse(delayTime); break;
    case 2: pattern_pingpong(delayTime); break;
    case 3: pattern_inout(delayTime); break;
    case 4: pattern_alternate(delayTime); break;
    case 5: pattern_randomSparkle(delayTime); break;
  }
}

// ---------------------------------------------------------
void pattern_normal(int d) {
  for (int i = 0; i < 16; i++) {
    allOff(); digitalWrite(leds[i], HIGH); delay(d);
  }
}

void pattern_reverse(int d) {
  for (int i = 15; i >= 0; i--) {
    allOff(); digitalWrite(leds[i], HIGH); delay(d);
  }
}

void pattern_pingpong(int d) {
  pattern_normal(d);
  pattern_reverse(d);
}

void pattern_inout(int d) {
  for (int i = 0; i < 8; i++) {
    allOff();
    digitalWrite(leds[7 - i], HIGH);
    digitalWrite(leds[8 + i], HIGH);
    delay(d);
  }
  for (int i = 7; i >= 0; i--) {
    allOff();
    digitalWrite(leds[7 - i], HIGH);
    digitalWrite(leds[8 + i], HIGH);
    delay(d);
  }
}

void pattern_alternate(int d) {
  allOff();
  for (int i = 0; i < 16; i += 2) digitalWrite(leds[i], HIGH);
  delay(d);

  allOff();
  for (int i = 1; i < 16; i += 2) digitalWrite(leds[i], HIGH);
  delay(d);
}

void pattern_randomSparkle(int d) {
  allOff();
  digitalWrite(leds[random(0,16)], HIGH);
  delay(d);
}

void allOff() {
  for (int i = 0; i < 16; i++) digitalWrite(leds[i], LOW);
}