// ============================================================
// explode.ino  —  Bomb Detector
//
//   Place a piece on either promotion rank (row 0 or row 7)
//   and that square counts down to detonation.
//   8 blinks: slow → exponentially faster, like a bomb fuse.
//   The square stays lit red at the end.
//   Pieces placed on any other row are ignored.
//   Only the triggered square ever lights up — nothing else.
//
//   Place another piece on a back rank to trigger again.
// ============================================================

#include <Adafruit_NeoPixel.h>

// ── Hardware ─────────────────────────────────────────────────
#define LED_PIN    1
#define LED_COUNT  64
#define BRIGHTNESS 150

#define SER_PIN    45
#define RCLK_PIN   47
#define SRCLK_PIN  46

const int ROW_PINS[8] = {42, 41, 40, 39, 38, 37, 36, 35};

Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_RGBW + NEO_KHZ800);

// ── Sensor state ──────────────────────────────────────────────
bool sensor[8][8], sensorPrev[8][8];
bool exploded[8][8];   // squares currently glowing red after a countdown

// ── Hardware helpers ──────────────────────────────────────────
void setColumn(int col) {
  digitalWrite(RCLK_PIN, LOW);
  for (int i = 7; i >= 0; i--) {
    digitalWrite(SRCLK_PIN, LOW);
    digitalWrite(SER_PIN, (i == col) ? HIGH : LOW);
    digitalWrite(SRCLK_PIN, HIGH);
  }
  digitalWrite(RCLK_PIN, HIGH);
}
void clearCols() {
  digitalWrite(RCLK_PIN, LOW);
  for (int i = 0; i < 8; i++) {
    digitalWrite(SRCLK_PIN, LOW);
    digitalWrite(SER_PIN, LOW);
    digitalWrite(SRCLK_PIN, HIGH);
  }
  digitalWrite(RCLK_PIN, HIGH);
}
void readSensors() {
  for (int c = 0; c < 8; c++) {
    setColumn(c);
    delayMicroseconds(10);
    for (int r = 0; r < 8; r++)
      sensor[r][c] = (digitalRead(ROW_PINS[r]) == LOW);
  }
  clearCols();
}

// ── Red color — strip is physically GRBW so swap R↔G ─────────
#define RED strip.Color(0, 255, 0, 0)

// ── Blink intervals (ms) — exponential decay, 8 steps ────────
// 2 slow, then ripping faster each time
const int BLINK_MS[8] = { 450, 380, 260, 170, 110, 70, 40, 20 };

// ── Countdown and hold on a single pixel ─────────────────────
void detonate(int row, int col) {
  int px = row * 8 + col;

  for (int i = 0; i < 8; i++) {
    // ON
    strip.setPixelColor(px, RED);
    strip.show();
    delay(BLINK_MS[i]);

    // OFF  (skip the last off so it stays lit)
    if (i < 7) {
      strip.setPixelColor(px, 0);
      strip.show();
      delay(BLINK_MS[i]);
    }
  }

  // Leave the square lit red while the piece is still there
  strip.setPixelColor(px, RED);
  strip.show();
  exploded[row][col] = true;
}

// ── Setup ─────────────────────────────────────────────────────
void setup() {
  pinMode(SER_PIN,   OUTPUT);
  pinMode(RCLK_PIN,  OUTPUT);
  pinMode(SRCLK_PIN, OUTPUT);
  for (int i = 0; i < 8; i++) pinMode(ROW_PINS[i], INPUT_PULLUP);

  strip.begin();
  strip.setBrightness(BRIGHTNESS);
  strip.clear();
  strip.show();

  memset(exploded, 0, sizeof(exploded));
  readSensors();
  memcpy(sensorPrev, sensor, sizeof(sensor));
}

// ── Loop ──────────────────────────────────────────────────────
void loop() {
  readSensors();

  for (int r = 0; r < 8; r++) {
    for (int c = 0; c < 8; c++) {
      // Piece removed from an exploded square — clear the light
      if (exploded[r][c] && !sensor[r][c]) {
        strip.setPixelColor(r * 8 + c, 0);
        strip.show();
        exploded[r][c] = false;
      }
      // New piece placed on a back rank — trigger countdown
      if (sensor[r][c] && !sensorPrev[r][c] && (r == 0 || r == 7)) {
        detonate(r, c);
        readSensors();
        memcpy(sensorPrev, sensor, sizeof(sensor));
        return;
      }
    }
  }

  memcpy(sensorPrev, sensor, sizeof(sensor));
  delay(20);
}