const int led_pins[] = { 2, 3, 4, 5 };  // LEDs connected to pins
const int switch_pin = 12;              // Pin for the switch

// Arrays related to LED Patterns
const int pattern_lengths[] = { 2, 2, 4, 2, 2 };
const int patterns[][4][4] = {
  { { 1, 1, 1, 1 }, { 0, 0, 0, 0 } },                                  // Pattern 0
  { { 1, 0, 1, 0 }, { 0, 1, 0, 1 } },                                  // Pattern 1
  { { 1, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 1 } },  // Pattern 2
  { { 1, 1, 0, 0 }, { 0, 0, 1, 1 } },                                  // Pattern 3
  { { 1, 0, 0, 1 }, { 0, 1, 1, 0 } }                                   // Pattern 4
};

unsigned int flag_check = 1;           // Controls the execution of the current pattern
int pattern_index = 0;                 // Current pattern index
unsigned long debounce_delay = 50;     // Debounce delay in milliseconds
int last_button_state = 1;             // Previous button state (1: not pressed, 0: pressed)
int current_button_state = 1;          // Current button state
unsigned long last_debounce_time = 0;  // Timestamp of the last button state change

void setup() {

  for (int i = 0; i < 4; i++) {
    pinMode(led_pins[i], OUTPUT);
  }

  pinMode(switch_pin, INPUT_PULLUP);
}

void loop() {
  // Execute the selected pattern
  while (flag_check) {
    // Iterate through each step of the current pattern
    for (int j = 0; j < pattern_lengths[pattern_index]; j++) {
      set_leds(patterns[pattern_index][j]);       // Set LEDs for the current step
      flag_check = delay_with_button_check(500);  // Wait with button check
      if (!flag_check) break;                     // Exit if the button is pressed
    }
    if (!flag_check) break;  // Exit the pattern loop if the button is pressed
  }
  flag_check = 1;  // Reset flag after pattern completion
}


// Checks if the button is pressed and debounced.

bool is_debounced_press(int button_pin) {
  int reading = digitalRead(button_pin);

  // If the button state has changed, reset the debounce timer
  if (reading != last_button_state) {
    last_debounce_time = millis();
  }
  last_button_state = reading;
  // If the button state is stable for more than 50 msec the debounce delay, update the state.
  if ((millis() - last_debounce_time) > debounce_delay) {
    if (reading != current_button_state) {
      current_button_state = reading;

      // Return true if the button is pressed (LOW state)
      if (current_button_state == 0) {
        return true;  // valid press detected
      }
    }
  }
  return false;  // No valid press detected
}


// Implements a delay while checking for button press.

bool delay_with_button_check(long delay_duration) {
  long delay_start_time = millis();  // Record the start time of the delay
  while ((millis() - delay_start_time) < delay_duration) {
    if (is_debounced_press(switch_pin)) {
      pattern_index = (pattern_index + 1) % 5;  // Cycle to the next pattern
      return false;                             // Exit delay early
    }
  }
  return true;  // Continue executing the pattern
}

// Set the states of the LEDs
void set_leds(const int states[]) {
  for (int i = 0; i < 4; i++) {
    digitalWrite(led_pins[i], states[i]);
  }
}