#include <Adafruit_NeoPixel.h>

// -----------------------------
// CONFIGURACIÓN DE PINES
// -----------------------------
#define LED_PIN       D0
#define LED_COUNT     16       // cambia según tu tira o aro RGB
#define BUZZER_PIN    D1

// UART hacia Nextion
#define NEXTION_SERIAL Serial1

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

// -----------------------------
// ESTADOS
// -----------------------------
enum TimerState {
  STOPPED,
  RUNNING,
  PAUSED,
  FINISHED
};

TimerState timerState = STOPPED;

// presets en segundos
const uint32_t PRESET_5_MIN = 300;
const uint32_t PRESET_4_MIN = 240;
const uint32_t PRESET_3_MIN = 180;

uint32_t selectedDuration = PRESET_5_MIN;
uint32_t remainingSeconds = PRESET_5_MIN;

unsigned long lastTickMs = 0;
unsigned long lastDisplayUpdateMs = 0;

bool buzzerActive = false;
unsigned long buzzerStartMs = 0;

// buffer serial
String rxLine = "";

// -----------------------------
// FUNCIONES AUXILIARES
// -----------------------------
void nextionEnd() {
  NEXTION_SERIAL.write(0xFF);
  NEXTION_SERIAL.write(0xFF);
  NEXTION_SERIAL.write(0xFF);
}

void nextionCommand(const String &cmd) {
  NEXTION_SERIAL.print(cmd);
  nextionEnd();
}

void updateDisplayTime(uint32_t totalSeconds) {
  uint32_t minutes = totalSeconds / 60;
  uint32_t seconds = totalSeconds % 60;

  char buffer[10];
  sprintf(buffer, "%02lu:%02lu", minutes, seconds);

  String cmd = "t0.txt=\"";
  cmd += buffer;
  cmd += "\"";
  nextionCommand(cmd);
}

void setAllPixels(uint8_t r, uint8_t g, uint8_t b) {
  for (int i = 0; i < LED_COUNT; i++) {
    strip.setPixelColor(i, strip.Color(r, g, b));
  }
  strip.show();
}

void updateLedByTime() {
  if (timerState == STOPPED || timerState == PAUSED) {
    // mostrar color según estado actual del tiempo
  }

  if (remainingSeconds <= 10) {
    // rojo
    setAllPixels(255, 0, 0);
  } else if (remainingSeconds <= (selectedDuration * 20UL) / 100UL) {
    // amarillo
    setAllPixels(255, 180, 0);
  } else {
    // verde
    setAllPixels(0, 255, 0);
  }
}

void stopTimerAndResetToSelected() {
  timerState = STOPPED;
  remainingSeconds = selectedDuration;
  updateDisplayTime(remainingSeconds);
  updateLedByTime();
}

void startTimer() {
  if (remainingSeconds == 0) {
    remainingSeconds = selectedDuration;
  }
  timerState = RUNNING;
  lastTickMs = millis();
  updateLedByTime();
}

void pauseTimer() {
  if (timerState == RUNNING) {
    timerState = PAUSED;
  }
}

void finishTimer() {
  timerState = FINISHED;
  remainingSeconds = 0;
  updateDisplayTime(remainingSeconds);
  setAllPixels(255, 0, 0);

  buzzerActive = true;
  buzzerStartMs = millis();
  tone(BUZZER_PIN, 2000);   // 2 kHz
}

void setPresetMinutes(uint8_t minutes) {
  switch (minutes) {
    case 5:
      selectedDuration = PRESET_5_MIN;
      break;
    case 4:
      selectedDuration = PRESET_4_MIN;
      break;
    case 3:
      selectedDuration = PRESET_3_MIN;
      break;
    default:
      return;
  }

  timerState = STOPPED;
  remainingSeconds = selectedDuration;
  updateDisplayTime(remainingSeconds);
  updateLedByTime();
}

void processCommand(String cmd) {
  cmd.trim();

  if (cmd == "START") {
    startTimer();
  }
  else if (cmd == "PAUSE") {
    pauseTimer();
  }
  else if (cmd == "RESET") {
    stopTimerAndResetToSelected();
  }
  else if (cmd.startsWith("PRESET:")) {
    int val = cmd.substring(7).toInt();
    setPresetMinutes(val);
  }
}

void readNextionSerial() {
  while (NEXTION_SERIAL.available()) {
    char c = NEXTION_SERIAL.read();

    // filtramos bytes FF de terminación si aparecen
    if ((uint8_t)c == 0xFF) continue;

    if (c == '\n' || c == '\r') {
      if (rxLine.length() > 0) {
        processCommand(rxLine);
        rxLine = "";
      }
    } else {
      rxLine += c;

      // por seguridad, si el comando ya es reconocible
      if (rxLine == "START" || rxLine == "PAUSE" || rxLine == "RESET" ||
          rxLine == "PRESET:5" || rxLine == "PRESET:4" || rxLine == "PRESET:3") {
        processCommand(rxLine);
        rxLine = "";
      }
    }
  }
}

// -----------------------------
// SETUP
// -----------------------------
void setup() {
  pinMode(BUZZER_PIN, OUTPUT);
  noTone(BUZZER_PIN);

  Serial.begin(115200);
  NEXTION_SERIAL.begin(9600);

  strip.begin();
  strip.show();

  selectedDuration = PRESET_5_MIN;
  remainingSeconds = selectedDuration;

  delay(500);
  updateDisplayTime(remainingSeconds);
  updateLedByTime();
}

// -----------------------------
// LOOP
// -----------------------------
void loop() {
  readNextionSerial();

  unsigned long now = millis();

  if (timerState == RUNNING) {
    if (now - lastTickMs >= 1000) {
      lastTickMs += 1000;

      if (remainingSeconds > 0) {
        remainingSeconds--;
        updateDisplayTime(remainingSeconds);
        updateLedByTime();
      }

      if (remainingSeconds == 0) {
        finishTimer();
      }
    }
  }

  if (buzzerActive) {
    if (now - buzzerStartMs >= 5000) {
      noTone(BUZZER_PIN);
      buzzerActive = false;
    }
  }
}