VoiceRSSSummary/services/text-converter.ts

import Kuroshiro from "kuroshiro";
import KuroshiroAnalyzerMecab from "kuroshiro-analyzer-mecab";
import { toKatakana } from "wanakana";

// Global instance to avoid recreating the analyzer
let kuroshiroInstance: Kuroshiro | null = null;

// Basic English to Katakana mapping for common words
const englishToKatakanaMap: Record<string, string> = {
  "hello": "ハロー",
  "world": "ワールド",
  "this": "ディス",
  "is": "イズ",
  "a": "ア",
  "test": "テスト",
  "javascript": "ジャバスクリプト",
  "typescript": "タイプスクリプト",
  "and": "アンド",
  "api": "エーピーアイ",
  "endpoint": "エンドポイント",
  "machine": "マシン",
  "learning": "ラーニング",
  "model": "モデル",
  "analysis": "アナリシス",
  "computer": "コンピューター",
  "data": "データ",
  "software": "ソフトウェア",
  "program": "プログラム",
  "system": "システム",
  "network": "ネットワーク",
  "server": "サーバー",
  "client": "クライアント",
  "database": "データベース",
  "file": "ファイル",
  "user": "ユーザー",
  "password": "パスワード",
  "login": "ログイン",
  "logout": "ログアウト",
  "website": "ウェブサイト",
  "browser": "ブラウザー",
  "application": "アプリケーション",
  "service": "サービス"
};

/**
 * Convert English word to Katakana using predefined mapping or phonetic approximation
 */
function convertEnglishWordToKatakana(word: string): string {
  const lowerWord = word.toLowerCase();
  
  // Check predefined mapping first
  if (englishToKatakanaMap[lowerWord]) {
    return englishToKatakanaMap[lowerWord];
  }
  
  // Try using wanakana for romanized pronunciation
  try {
    // Convert to a rough romanized version and then to katakana
    const katakana = toKatakana(word.toLowerCase());
    if (katakana && katakana !== word.toLowerCase()) {
      return katakana;
    }
  } catch {
    // Fallback if wanakana fails
  }
  
  // Fallback: simple phonetic approximation
  return approximateEnglishToKatakana(word);
}

/**
 * Simple phonetic approximation for English to Katakana
 */
function approximateEnglishToKatakana(word: string): string {
  const phoneticMap: Record<string, string> = {
    'a': 'ア', 'b': 'ブ', 'c': 'ク', 'd': 'ド', 'e': 'エ',
    'f': 'フ', 'g': 'グ', 'h': 'ハ', 'i': 'イ', 'j': 'ジ',
    'k': 'ク', 'l': 'ル', 'm': 'ム', 'n': 'ン', 'o': 'オ',
    'p': 'プ', 'q': 'ク', 'r': 'ル', 's': 'ス', 't': 'ト',
    'u': 'ウ', 'v': 'ブ', 'w': 'ワ', 'x': 'クス', 'y': 'ワイ', 'z': 'ズ'
  };
  
  return word.toLowerCase()
    .split('')
    .map(char => phoneticMap[char] || char)
    .join('');
}

/**
 * Initialize kuroshiro with MeCab analyzer
 * This should be called once during application startup
 */
export async function initializeTextConverter(): Promise<void> {
  if (kuroshiroInstance) {
    return; // Already initialized
  }

  try {
    console.log("Kuroshiroテキストコンバーターを初期化中...");
    kuroshiroInstance = new Kuroshiro();
    await kuroshiroInstance.init(new KuroshiroAnalyzerMecab());
    console.log("Kuroshiroテキストコンバーター初期化完了");
  } catch (error) {
    console.error("Kuroshiroの初期化に失敗しました:", error);
    throw error;
  }
}

/**
 * Convert English words and mixed text to katakana
 * @param text - Input text (may contain Japanese, English, and other characters)
 * @returns Text with English words converted to katakana
 */
export async function convertEnglishToKatakana(text: string): Promise<string> {
  if (!kuroshiroInstance) {
    await initializeTextConverter();
  }

  if (!kuroshiroInstance) {
    throw new Error("Failed to initialize kuroshiro");
  }

  try {
    // Convert the entire text to katakana
    // This will convert both Japanese hiragana and English words to katakana
    const convertedText = await kuroshiroInstance.convert(text, {
      to: "katakana",
      mode: "normal",
    });

    return convertedText;
  } catch (error) {
    console.error("テキスト変換エラー:", error);
    // Return original text if conversion fails
    return text;
  }
}

/**
 * Convert only English words to katakana while preserving Japanese text
 * This is a more selective approach that tries to preserve Japanese characters
 * @param text - Input text
 * @returns Text with only English words converted to katakana
 */
export async function convertEnglishWordsOnly(text: string): Promise<string> {
  if (!kuroshiroInstance) {
    await initializeTextConverter();
  }

  if (!kuroshiroInstance) {
    throw new Error("Failed to initialize kuroshiro");
  }

  try {
    // Extract English words using regex
    const englishWordPattern = /\b[a-zA-Z]+\b/g;
    let result = text;
    
    // Find all English words
    const matches = text.match(englishWordPattern);
    
    if (matches) {
      for (const englishWord of matches) {
        try {
          // Convert each English word to katakana using our custom function
          const converted = convertEnglishWordToKatakana(englishWord);
          
          // Replace the English word with its katakana equivalent
          // Use word boundary to avoid partial replacements
          const wordRegex = new RegExp(`\\b${englishWord.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}\\b`, 'g');
          result = result.replace(wordRegex, converted);
        } catch (convertError) {
          console.warn(`Failed to convert word "${englishWord}":`, convertError);
          // Keep original word if conversion fails
        }
      }
    }

    return result;
  } catch (error) {
    console.error("選択的テキスト変換エラー:", error);
    // Fallback to full conversion
    return convertEnglishToKatakana(text);
  }
}

/**
 * Check if kuroshiro is initialized
 */
export function isTextConverterInitialized(): boolean {
  return kuroshiroInstance !== null;
}