/**
 * D3RO-VOICE 효과음 WAV 파일 생성 스크립트
 *
 * 생성 파일:
 *   resources/sounds/recording-start.wav  — 상승 톤 (440→880Hz, 150ms)
 *   resources/sounds/recording-stop.wav   — 하강 톤 (880→440Hz, 150ms)
 *   resources/sounds/error.wav            — 저음 비프 2회 (220Hz, 200ms×2)
 *
 * WAV 포맷: 16kHz, mono, 16bit PCM
 */

const fs = require('fs');
const path = require('path');

const SAMPLE_RATE = 16000;
const BIT_DEPTH = 16;
const NUM_CHANNELS = 1;
const BYTES_PER_SAMPLE = BIT_DEPTH / 8;

/**
 * 사인파 샘플 생성 (주파수 선형 스윕 지원)
 * @param {number} durationMs - 길이 (ms)
 * @param {number} freqStart - 시작 주파수 (Hz)
 * @param {number} freqEnd - 끝 주파수 (Hz)
 * @param {number} volume - 볼륨 (0.0~1.0)
 * @returns {Int16Array}
 */
function generateTone(durationMs, freqStart, freqEnd, volume = 0.6) {
  const numSamples = Math.floor((SAMPLE_RATE * durationMs) / 1000);
  const samples = new Int16Array(numSamples);
  const maxVal = 32767 * volume;

  // 페이드 인/아웃 길이 (클릭 방지)
  const fadeSamples = Math.min(Math.floor(numSamples * 0.05), 80);

  let phase = 0;
  for (let i = 0; i < numSamples; i++) {
    const t = i / numSamples;
    const freq = freqStart + (freqEnd - freqStart) * t;

    // 페이드 인/아웃 엔벨로프
    let envelope = 1.0;
    if (i < fadeSamples) {
      envelope = i / fadeSamples;
    } else if (i > numSamples - fadeSamples) {
      envelope = (numSamples - i) / fadeSamples;
    }

    samples[i] = Math.round(Math.sin(phase) * maxVal * envelope);
    phase += (2 * Math.PI * freq) / SAMPLE_RATE;
  }

  return samples;
}

/**
 * 무음 생성
 * @param {number} durationMs
 * @returns {Int16Array}
 */
function generateSilence(durationMs) {
  const numSamples = Math.floor((SAMPLE_RATE * durationMs) / 1000);
  return new Int16Array(numSamples);
}

/**
 * 여러 샘플 배열을 이어붙임
 * @param {Int16Array[]} arrays
 * @returns {Int16Array}
 */
function concatenate(arrays) {
  const totalLength = arrays.reduce((sum, arr) => sum + arr.length, 0);
  const result = new Int16Array(totalLength);
  let offset = 0;
  for (const arr of arrays) {
    result.set(arr, offset);
    offset += arr.length;
  }
  return result;
}

/**
 * PCM 데이터를 WAV 파일 버퍼로 변환
 * @param {Int16Array} samples
 * @returns {Buffer}
 */
function createWavBuffer(samples) {
  const dataSize = samples.length * BYTES_PER_SAMPLE;
  const headerSize = 44;
  const buffer = Buffer.alloc(headerSize + dataSize);

  // RIFF header
  buffer.write('RIFF', 0);
  buffer.writeUInt32LE(headerSize - 8 + dataSize, 4);
  buffer.write('WAVE', 8);

  // fmt chunk
  buffer.write('fmt ', 12);
  buffer.writeUInt32LE(16, 16); // chunk size
  buffer.writeUInt16LE(1, 20); // PCM format
  buffer.writeUInt16LE(NUM_CHANNELS, 22);
  buffer.writeUInt32LE(SAMPLE_RATE, 24);
  buffer.writeUInt32LE(SAMPLE_RATE * NUM_CHANNELS * BYTES_PER_SAMPLE, 28); // byte rate
  buffer.writeUInt16LE(NUM_CHANNELS * BYTES_PER_SAMPLE, 32); // block align
  buffer.writeUInt16LE(BIT_DEPTH, 34);

  // data chunk
  buffer.write('data', 36);
  buffer.writeUInt32LE(dataSize, 40);

  // PCM data (Int16 little-endian)
  const pcmBuffer = Buffer.from(samples.buffer, samples.byteOffset, samples.byteLength);
  pcmBuffer.copy(buffer, headerSize);

  return buffer;
}

// --- 효과음 생성 ---

const outputDir = path.resolve(__dirname, '..', 'resources', 'sounds');
fs.mkdirSync(outputDir, { recursive: true });

// 1. recording-start.wav: 상승 톤 440→880Hz, 150ms
const startSamples = generateTone(150, 440, 880, 0.5);
const startWav = createWavBuffer(startSamples);
const startPath = path.join(outputDir, 'recording-start.wav');
fs.writeFileSync(startPath, startWav);
console.log(`Created: ${startPath} (${startWav.length} bytes)`);

// 2. recording-stop.wav: 하강 톤 880→440Hz, 150ms
const stopSamples = generateTone(150, 880, 440, 0.5);
const stopWav = createWavBuffer(stopSamples);
const stopPath = path.join(outputDir, 'recording-stop.wav');
fs.writeFileSync(stopPath, stopWav);
console.log(`Created: ${stopPath} (${stopWav.length} bytes)`);

// 3. error.wav: 220Hz 비프 200ms × 2회, 중간 100ms 무음
const beep1 = generateTone(200, 220, 220, 0.5);
const gap = generateSilence(100);
const beep2 = generateTone(200, 220, 220, 0.5);
const errorSamples = concatenate([beep1, gap, beep2]);
const errorWav = createWavBuffer(errorSamples);
const errorPath = path.join(outputDir, 'error.wav');
fs.writeFileSync(errorPath, errorWav);
console.log(`Created: ${errorPath} (${errorWav.length} bytes)`);

console.log('\nDone! All 3 sound files generated.');