#include <math.h>

// --- デバッグモード有効 ---
#define DEBUG

// --- モールスデコーダ設定パラメータ ---
#define WPM 20                    // 受信速度 (Words Per Minute)
#define GOERTZEL_N 48             // Goertzelアルゴリズムのサンプル数
#define THRESHOLD 10000           // トーン検出の閾値
#define LED_PIN 13                // デバッグ用LED出力ピン
#define SAMPLE_RATE 8900          // サンプリングレート(Hz)
#define TARGET_FREQ 700           // 検出対象周波数(Hz)
#define AUDIO_PIN A0              // オーディオ入力ピン
#define MAX_MORSE_LEN 10          // 1文字あたりの最大モールス長

#define ADC_READ_US 100           // ADC読み取りにかかる時間(マイクロ秒)
#define LOOP_DELAY_MS 2           // メインループ遅延(ミリ秒)
#define VARIABLE_DELAY_COEFF 0.05 // 可変遅延補正係数
#define ADAPTIVE_BUF_LEN 10       // ドット長適応用バッファサイズ

// --- タイミング補正値 ---
const float goertzelDelay = (float)GOERTZEL_N * 1000.0 / SAMPLE_RATE;
const float adcDelay = (float)GOERTZEL_N * ADC_READ_US / 1000.0;
const float baseDelay = goertzelDelay + adcDelay + LOOP_DELAY_MS;

// --- モールス符号バッファ ---
char morseBuffer[MAX_MORSE_LEN + 1]; // 1文字分の.と-を記録
uint8_t morseLen = 0;                // morseBufferの長さ

// --- タイミング管理 ---
unsigned long lastOnTime = 0;        // 直前のON開始時刻
unsigned long lastOffTime = 0;       // 直前のOFF開始時刻
unsigned long spaceStartTime = 0;    // スペース開始時刻
bool lastTone = false;               // 直前のトーン状態

// --- ドット長適応用バッファ ---
float dotBuf[ADAPTIVE_BUF_LEN] = {0};
uint8_t dotIdx = 0, dotCount = 0;
float adaptiveDotLen = 1200.0 / WPM; // 適応的ドット長（ms）

// --- ON区間一時バッファ ---
float pendingOnDuration = 0;         // ON区間長の一時保存
bool pendingOnValid = false;         // pendingOnDurationが有効か

// --- デバッグ出力ON/OFFトグル用 ---
bool debugEnabled = true;

// --- モールス符号テーブル（線形探索） ---
struct MorseTable {
  const char* code;
  char letter;
};
const MorseTable morseTable[] = {
  {".-", 'A'},   {"-...", 'B'}, {"-.-.", 'C'}, {"-..", 'D'}, {".", 'E'},
  {"..-.", 'F'}, {"--.", 'G'},  {"....", 'H'}, {"..", 'I'},  {".---", 'J'},
  {"-.-", 'K'},  {".-..", 'L'}, {"--", 'M'},   {"-.", 'N'},  {"---", 'O'},
  {".--.", 'P'}, {"--.-", 'Q'}, {".-.", 'R'},  {"...", 'S'}, {"-", 'T'},
  {"..-", 'U'},  {"...-", 'V'}, {".--", 'W'},  {"-..-", 'X'},{"-.--", 'Y'},
  {"--..", 'Z'},
  {"-----", '0'},{".----", '1'},{"..---", '2'},{"...--", '3'},{"....-", '4'},
  {".....", '5'},{"-....", '6'},{"--...", '7'},{"---..", '8'},{"----.", '9'},
  {".-.-.-", '.'},{"--..--", ','},{"..--..", '?'},{"-..-.", '/'},
  {"-...=", '='},{".-.-.", '+'},{"-....-", '-'},{"---...", ':'},
  {".----.", '\''},{"-.--.", '('},{"-.--.-", ')'}, {".--.-.", '@'},{"-.-.--", '!'}
};
const int morseTableSize = sizeof(morseTable) / sizeof(MorseTable);

// --- バッファの中央値計算（ドット長適応用） ---
float median(float* arr, uint8_t len) {
  float temp[ADAPTIVE_BUF_LEN];
  for (uint8_t i = 0; i < len; i++) temp[i] = arr[i];
  for (uint8_t i = 0; i < len - 1; i++)
    for (uint8_t j = i + 1; j < len; j++)
      if (temp[i] > temp[j]) { float t = temp[i]; temp[i] = temp[j]; temp[j] = t; }
  if (len % 2 == 1) return temp[len / 2];
  else return (temp[len / 2 - 1] + temp[len / 2]) / 2.0;
}

// --- Goertzelアルゴリズムによるトーン検出 ---
float goertzel(uint8_t pin) {
  float s_prev = 0, s_prev2 = 0, coeff, Q;
  float omega = (2.0 * 3.141592653589793 * TARGET_FREQ) / SAMPLE_RATE;
  coeff = 2.0 * cos(omega);

  for (int i = 0; i < GOERTZEL_N; i++) {
    int sample = analogRead(pin) - 512;
    Q = coeff * s_prev - s_prev2 + sample;
    s_prev2 = s_prev;
    s_prev = Q;
    delayMicroseconds(1000000 / SAMPLE_RATE);
  }
  float power = s_prev2 * s_prev2 + s_prev * s_prev - coeff * s_prev * s_prev2;
  return power;
}

// --- モールス符号列をテーブル照合でデコード ---
char decodeMorse(const char* code) {
  for (int i = 0; i < morseTableSize; i++) {
    if (strcmp(code, morseTable[i].code) == 0) return morseTable[i].letter;
  }
  return '?';
}

// --- モールスバッファクリア ---
void clearMorseBuffer() {
  for (uint8_t i = 0; i < MAX_MORSE_LEN + 1; i++) morseBuffer[i] = 0;
  morseLen = 0;
}

// --- バッファ内容をデコード・出力しクリア ---
void decodeAndClearBuffer() {
  morseBuffer[morseLen] = '\0';
  if (morseLen >= 1 && morseLen <= 6) {
    char decoded = decodeMorse(morseBuffer);
    Serial.print(decoded);
#ifdef DEBUG
    if (debugEnabled) Serial.println();
#endif
  }
  clearMorseBuffer();
}

// --- ドット長適応処理（移動中央値） ---
void updateAdaptiveDotLen(float pulse) {
  if (pulse > 30 && pulse < 1.5 * adaptiveDotLen) {
    dotBuf[dotIdx] = pulse;
    dotIdx = (dotIdx + 1) % ADAPTIVE_BUF_LEN;
    if (dotCount < ADAPTIVE_BUF_LEN) dotCount++;
    adaptiveDotLen = median(dotBuf, dotCount);
  }
}

// --- ON→OFFエッジ処理：ON区間長バッファリングとノイズ除去 ---
void handleOnToOffEdge(unsigned long now, unsigned long &lastOnTime, unsigned long &lastOffTime, unsigned long &spaceStartTime, bool &lastTone, float power) {
  unsigned long rawOnDuration = now - lastOnTime;
  float variableOnDelay = VARIABLE_DELAY_COEFF * rawOnDuration;
  unsigned long onDuration = (rawOnDuration > baseDelay + variableOnDelay) ? rawOnDuration - baseDelay - variableOnDelay : 0;

#ifdef DEBUG
  if (debugEnabled) {
    Serial.print("  [ON→OFF] now:"); Serial.print(now);
    Serial.print(" lastOnTime:"); Serial.print(lastOnTime);
    Serial.print(" rawOnDuration:"); Serial.print(rawOnDuration);
    Serial.print(" onDuration:"); Serial.print(onDuration);
    Serial.print(" ("); Serial.print((float)onDuration / adaptiveDotLen, 2); Serial.print("dot)");
    Serial.print(" power:"); Serial.print(power);
    Serial.print(" morseBuffer:[");
    for (uint8_t i = 0; i < morseLen; i++) Serial.print(morseBuffer[i]);
    Serial.print("]");
  }
#endif

  // --- 短いONノイズは無視 ---
  if (onDuration < 0.2 * adaptiveDotLen) {
    pendingOnValid = false;
#ifdef DEBUG
    if (debugEnabled) Serial.println(" [NOISE: short ON] (reset pending)");
#endif
    return;
  }

#ifdef DEBUG
  if (debugEnabled) Serial.println();
#endif

  // --- ON区間長を一時バッファに蓄積 ---
  if (pendingOnValid) {
    pendingOnDuration += onDuration;
  } else {
    pendingOnDuration = onDuration;
    pendingOnValid = true;
  }
  lastOffTime = now;
  spaceStartTime = now;
}

// --- OFF→ONエッジ処理：点・線判定とスペース判定 ---
void handleOffToOnEdge(unsigned long now, unsigned long &lastOnTime, unsigned long &lastOffTime, unsigned long &spaceStartTime, float power) {
  unsigned long rawOffDuration = now - lastOffTime;
  float variableOffDelay = VARIABLE_DELAY_COEFF * rawOffDuration;
  unsigned long offDuration = (rawOffDuration > baseDelay + variableOffDelay) ? rawOffDuration - baseDelay - variableOffDelay : 0;

#ifdef DEBUG
  if (debugEnabled) {
    Serial.print("  [OFF→ON] now:"); Serial.print(now);
    Serial.print(" lastOffTime:"); Serial.print(lastOffTime);
    Serial.print(" rawOffDuration:"); Serial.print(rawOffDuration);
    Serial.print(" offDuration:"); Serial.print(offDuration);
    Serial.print(" ("); Serial.print((float)offDuration / adaptiveDotLen, 2); Serial.print("dot)");
    Serial.print(" power:"); Serial.print(power);
  }
#endif

  // --- 短いOFFノイズは無視 ---
  if (offDuration < 0.2 * adaptiveDotLen) {
    pendingOnValid = false;
#ifdef DEBUG
    if (debugEnabled) Serial.println(" [NOISE: short OFF] (reset pending)");
#endif
    return;
  }

  lastOnTime = now;
  lastOffTime = now;

  // --- pendingOnDurationを点・線としてバッファに追加 ---
  if (pendingOnValid) {
    if (pendingOnDuration < 1.5 * adaptiveDotLen) {
      updateAdaptiveDotLen(pendingOnDuration);
      if (morseLen < MAX_MORSE_LEN) morseBuffer[morseLen++] = '.';
    } else {
      if (morseLen < MAX_MORSE_LEN) morseBuffer[morseLen++] = '-';
    }
    pendingOnValid = false;
  }

#ifdef DEBUG
  if (debugEnabled) {
    Serial.print(" morseBuffer:[");
    for (uint8_t i = 0; i < morseLen; i++) Serial.print(morseBuffer[i]);
    Serial.print("]");
  }
#endif

  // --- スペース長で文字・単語区切り判定 ---
  if (spaceStartTime > 0) {
    unsigned long spaceLen = now - spaceStartTime;
#ifdef DEBUG
    if (debugEnabled) {
      Serial.print(" spaceStartTime:"); Serial.print(spaceStartTime);
      Serial.print(" spaceLen:"); Serial.print(spaceLen);
      Serial.print(" ("); Serial.print((float)spaceLen / adaptiveDotLen, 2); Serial.print("dot)");
    }
#endif

    if ((spaceStartTime == 0 || spaceLen > 12 * adaptiveDotLen) && morseLen == 1) {
#ifdef DEBUG
      if (debugEnabled) Serial.println(" [clear morseBuffer:1char]");
#endif
      clearMorseBuffer();
    } 
    else if (spaceLen >= 6 * adaptiveDotLen) {
#ifdef DEBUG
      if (debugEnabled) Serial.print(" [単語間スペース]");
#endif
      if (morseLen > 0) {
#ifdef DEBUG
        if (debugEnabled) Serial.println(" decodeAndClearBuffer()");
#endif
        decodeAndClearBuffer();
      }
      Serial.print(' ');
#ifdef DEBUG
      if (debugEnabled) Serial.println();
#endif
    } 
    else if (spaceLen >= 2.2 * adaptiveDotLen) {
#ifdef DEBUG
      if (debugEnabled) Serial.print(" [文字間スペース]");
#endif
      if (morseLen > 0) {
#ifdef DEBUG
        if (debugEnabled) Serial.println(" decodeAndClearBuffer()");
#endif
        decodeAndClearBuffer();
      }
    } 
    else {
#ifdef DEBUG
      if (debugEnabled) Serial.println(" [文字中スペース]");
#endif
    }
  } else {
#ifdef DEBUG
    if (debugEnabled) Serial.println();
#endif
  }
  spaceStartTime = 0;
}

// --- 長いOFFで強制バッファ確定・デコード ---
void handleLongOff(unsigned long now, unsigned long &spaceStartTime) {
  if (!lastTone && spaceStartTime > 0) {
    unsigned long spaceLen = now - spaceStartTime;
    if (spaceLen >= 14 * adaptiveDotLen) {
#ifdef DEBUG
      if (debugEnabled) {
        Serial.print("  [OFF長] now:"); Serial.print(now);
        Serial.print(" spaceStartTime:"); Serial.print(spaceStartTime);
        Serial.print(" spaceLen:"); Serial.print(spaceLen);
        Serial.print(" ("); Serial.print((float)spaceLen / adaptiveDotLen, 2); Serial.print("dot) ");
      }
#endif
      if (pendingOnValid) {
        if (pendingOnDuration < 1.5 * adaptiveDotLen) {
          updateAdaptiveDotLen(pendingOnDuration);
          if (morseLen < MAX_MORSE_LEN) morseBuffer[morseLen++] = '.';
        } else {
          if (morseLen < MAX_MORSE_LEN) morseBuffer[morseLen++] = '-';
        }
        pendingOnValid = false;
        pendingOnDuration = 0;
      }
#ifdef DEBUG
      if (debugEnabled) {
        Serial.print(" morseBuffer:[");
        for (uint8_t i = 0; i < morseLen; i++) Serial.print(morseBuffer[i]);
        Serial.print("]");
      }
#endif
      if (morseLen > 0) {
#ifdef DEBUG
        if (debugEnabled) {
          Serial.print(" 強制デコード");
          Serial.println();
        }
#endif
        decodeAndClearBuffer();
        Serial.print(' ');
#ifdef DEBUG
        if (debugEnabled) Serial.println();
#endif
      }
      spaceStartTime = 0;
    }
  }
}

// --- Arduinoセットアップ ---
void setup() {
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(115200);
  lastOnTime = 0;
  lastOffTime = 0;
  spaceStartTime = 0;
  clearMorseBuffer();
#ifdef DEBUG
  Serial.println("CW Decoder (Goertzel, Table Matching) started.");
  Serial.print("WPM: "); Serial.println(WPM);
  Serial.print("dotLen: "); Serial.print(adaptiveDotLen); Serial.print(" ms (adaptive) ");
  Serial.print("GOERTZEL_N: "); Serial.println(GOERTZEL_N);
  Serial.print("THRESHOLD: "); Serial.println(THRESHOLD);
  Serial.print("goertzelDelay: "); Serial.print(goertzelDelay); Serial.print(" ms ");
  Serial.print("adcDelay: "); Serial.print(adcDelay); Serial.print(" ms ");
  Serial.print("baseDelay: "); Serial.print(baseDelay); Serial.print(" ms ");
  Serial.print("VARIABLE_DELAY_COEFF: "); Serial.print(VARIABLE_DELAY_COEFF); Serial.print(" ");
  Serial.println();
#endif
}

// --- メインループ ---
void loop() {
  // デバッグトグル処理（シリアルでd/D入力で切替）
  if (Serial.available() > 0) {
    char c = Serial.read();
    if (c == 'd' || c == 'D') {
      debugEnabled = !debugEnabled;
      Serial.print("Debug mode: ");
      Serial.println(debugEnabled ? "ON" : "OFF");
    }
  }

  float power;
  bool tone;
  // Goertzelでトーン検出
  while (true) {
    power = goertzel(AUDIO_PIN);
    if (power < THRESHOLD) {
      tone = false;
      break;
    } else if (power >= THRESHOLD * 2.0) {
      tone = true;
      break;
    }
  }

  digitalWrite(LED_PIN, tone ? HIGH : LOW);

  unsigned long now = millis();

  // エッジ検出と処理
  if (lastTone && !tone) {
    handleOnToOffEdge(now, lastOnTime, lastOffTime, spaceStartTime, lastTone, power);
  } else if (!lastTone && tone) {
    handleOffToOnEdge(now, lastOnTime, lastOffTime, spaceStartTime, power);
  }

  // 長いOFFで強制デコード
  handleLongOff(now, spaceStartTime);

  lastTone = tone;
}