#include <FastLED.h>
#include <avr/pgmspace.h>

// ================= HARDWARE =================
#define LED_PIN     12
#define COLOR_ORDER GRB
#define CHIPSET     WS2812
#define BRIGHTNESS  255

const uint8_t matrixWidth  = 32;
const uint8_t matrixHeight = 16;
#define NUM_LEDS (matrixWidth * matrixHeight)

CRGB leds[NUM_LEDS];   // Correct: no +1

// ================= 5x7 FONT =================
const uint8_t font5x7[96][5] PROGMEM = {
  {0,0,0,0,0},{0,0,95,0,0},{0,7,0,7,0},{20,127,20,127,20},
  {36,42,127,42,18},{35,19,8,100,98},{54,73,86,32,80},{0,7,0,0,0},
  {0,28,34,65,0},{0,65,34,28,0},{20,8,62,8,20},{8,8,62,8,8},
  {0,160,96,0,0},{8,8,8,8,8},{0,96,96,0,0},{32,16,8,4,2},
  {62,81,73,69,62},{0,66,127,64,0},{98,81,73,73,70},
  {34,65,73,73,54},{24,20,18,127,16},{39,69,69,69,57},
  {60,74,73,73,48},{1,113,9,5,3},{54,73,73,73,54},
  {6,73,73,41,30},{0,54,54,0,0},{0,182,102,0,0},
  {8,20,34,65,0},{20,20,20,20,20},{0,65,34,20,8},
  {2,1,89,9,6},{62,65,93,85,30},{126,17,17,17,126},
  {127,73,73,73,54},{62,65,65,65,34},{127,65,65,34,28},
  {127,73,73,73,65},{127,9,9,9,1},{62,65,73,73,122},
  {127,8,8,8,127},{0,65,127,65,0},{32,64,65,63,1},
  {127,8,20,34,65},{127,64,64,64,64},{127,2,12,2,127},
  {127,4,8,16,127},{62,65,65,65,62},{127,9,9,9,6},
  {62,65,97,33,94},{127,9,25,41,70},{38,73,73,73,50},
  {1,1,127,1,1},{63,64,64,64,63},{31,32,64,32,31},
  {63,64,56,64,63},{99,20,8,20,99},{3,4,120,4,3},
  {97,81,73,69,67},{0,127,65,65,0},{2,4,8,16,32},
  {0,65,65,127,0},{4,2,1,2,4},{64,64,64,64,64},
  {0,1,2,4,0},{32,84,84,84,120},{127,72,68,68,56},
  {56,68,68,68,32},{56,84,84,84,24},{8,126,9,1,2},
  {24,164,164,164,124},{127,8,4,4,120},{0,68,125,64,0},
  {64,128,128,122,0},{127,16,40,68,0},{0,65,127,64,0},
  {124,4,24,4,120},{124,8,4,4,120},{56,68,68,68,56},
  {124,20,20,20,8},{8,20,20,24,124},{124,8,4,4,8},
  {72,84,84,84,36},{4,63,68,64,32},{60,64,64,32,124},
  {28,32,64,32,28},{60,64,48,64,60},{68,40,16,40,68},
  {12,144,144,144,124},{68,100,84,76,68},{0,8,54,65,0},
  {0,0,119,0,0},{0,65,54,8,0},{2,1,2,4,2},{124,68,68,68,124}
};

// ================= XY =================
uint16_t XY(uint8_t x, uint8_t y) {
  if (x >= matrixWidth || y >= matrixHeight) return 0;
  if (y & 1) x = matrixWidth - 1 - x;   // serpentine layout
  return y * matrixWidth + x;
}

// ================= DRAW CHAR =================
void drawChar(int x, int y, char c, CRGB color) {
  if (c < 32 || c > 127) return;
  for (uint8_t col = 0; col < 5; col++) {
    uint8_t line = pgm_read_byte(&font5x7[c - 32][col]);
    for (uint8_t row = 0; row < 7; row++) {
      if (line & (1 << row))
        leds[XY(x + col, y + row)] = color;
    }
  }
}

// ================= DISPLAY NUMBER =================
void displayNumber(int num) {
  FastLED.clear();
  char buf[6];
  sprintf(buf, "%d", num);
  int startX = (matrixWidth - strlen(buf) * 6) / 2;
  int startY = 4;  // center vertically for 16 rows
  for (uint8_t i = 0; buf[i]; i++)
    drawChar(startX + i * 6, startY, buf[i], CRGB::Red);
  FastLED.show();
}

// ================= SERIAL VARIABLES =================
String serialText = "";
bool newData = false;

// ================= TIMER VARIABLES =================
unsigned long lastMillis = 0;
int countdown = 0;

// ================= READ SERIAL =================
void readSerial() {
  while (Serial.available()) {
    char c = Serial.read();
    if (c == '\n' || c == '\r') {
      if (serialText.length() > 0) newData = true;
    } else if (isDigit(c)) {
      serialText += c;
    }
  }
}

// ================= SETUP =================
void setup() {
  Serial.begin(9600);
  FastLED.addLeds<CHIPSET, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS);
  FastLED.setBrightness(BRIGHTNESS);

  displayNumber(88);   // show something immediately
  Serial.println("Enter countdown seconds and press ENTER:");
}

// ================= LOOP =================
void loop() {
  readSerial();

  // Start new countdown if Serial input received
  if (newData) {
    countdown = serialText.toInt();
    displayNumber(countdown);
    lastMillis = millis();
    Serial.print("Countdown started: ");
    Serial.println(countdown);
    serialText = "";
    newData = false;
  }

  // Countdown every second
  if (countdown > 0 && millis() - lastMillis >= 1000) {
    countdown--;
    displayNumber(countdown);
    lastMillis = millis();
  }
}