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import type { SpeechStatus, UseSpeechSynthesisReturn } from "../types";
// Chrome 15秒問題への対策: テキストをチャンクに分割
const CHUNK_SIZE = 200;
const DEFAULT_RATE = 1.0;
const MIN_RATE = 0.5;
const MAX_RATE = 2.0;
/**
* Web Speech API (SpeechSynthesis) を管理するカスタムフック
*/
export const useSpeechSynthesis = (): UseSpeechSynthesisReturn => {
const [status, setStatus] = useState<SpeechStatus>("idle");
const [rate, setRateState] = useState<number>(DEFAULT_RATE);
const [isSupported, setIsSupported] = useState<boolean>(false);
const [error, setError] = useState<string | null>(null);
const utteranceRef = useRef<SpeechSynthesisUtterance | null>(null);
const chunksRef = useRef<string[]>([]);
const currentChunkIndexRef = useRef<number>(0);
const synthRef = useRef<SpeechSynthesis | null>(null);
const currentLangRef = useRef<string>("ja-JP");
// ブラウザ対応チェック
useEffect(() => {
const supported =
typeof window !== "undefined" &&
"speechSynthesis" in window &&
"SpeechSynthesisUtterance" in window;
setIsSupported(supported);
if (supported) {
synthRef.current = window.speechSynthesis;
}
}, []);
// ページ遷移時のクリーンアップ
useEffect(() => {
return () => {
if (synthRef.current) {
synthRef.current.cancel();
}
};
}, []);
// 言語に適した音声を選択
const selectVoice = useCallback(
(lang: string): SpeechSynthesisVoice | null => {
Iif (!synthRef.current) return null;
const voices = synthRef.current.getVoices();
const langPrefix = lang.split("-")[0]; // 'ja-JP' -> 'ja'
// 優先順位: 完全一致 > プレフィックス一致 > デフォルト
return (
voices.find((v) => v.lang === lang) ||
voices.find((v) => v.lang.startsWith(langPrefix)) ||
voices.find((v) => v.default) ||
voices[0] ||
null
);
},
[],
);
// テキストを日本語/英語で判定
const detectLanguage = useCallback((text: string): string => {
const japaneseRegex = /[\u3040-\u309F\u30A0-\u30FF\u4E00-\u9FFF]/;
return japaneseRegex.test(text) ? "ja-JP" : "en-US";
}, []);
// テキストをチャンクに分割（Chrome 15秒問題対策）
const splitIntoChunks = useCallback((text: string): string[] => {
const chunks: string[] = [];
const sentences = text.split(/([。．.!?！？\n]+)/);
let currentChunk = "";
for (const sentence of sentences) {
Iif ((currentChunk + sentence).length > CHUNK_SIZE && currentChunk) {
chunks.push(currentChunk.trim());
currentChunk = sentence;
} else {
currentChunk += sentence;
}
}
Eif (currentChunk.trim()) {
chunks.push(currentChunk.trim());
}
return chunks.length > 0 ? chunks : [text];
}, []);
// 次のチャンクを読み上げ
const speakNextChunk = useCallback(() => {
Iif (!synthRef.current) return;
Iif (currentChunkIndexRef.current >= chunksRef.current.length) {
setStatus("idle");
currentChunkIndexRef.current = 0;
return;
}
const chunk = chunksRef.current[currentChunkIndexRef.current];
const utterance = new SpeechSynthesisUtterance(chunk);
utteranceRef.current = utterance;
utterance.rate = rate;
utterance.lang = currentLangRef.current;
const voice = selectVoice(currentLangRef.current);
Eif (voice) {
utterance.voice = voice;
}
utterance.onend = () => {
currentChunkIndexRef.current++;
speakNextChunk();
};
utterance.onerror = (event) => {
if (event.error !== "interrupted" && event.error !== "canceled") {
setError(`読み上げエラー: ${event.error}`);
setStatus("idle");
}
};
synthRef.current.speak(utterance);
setStatus("playing");
}, [rate, selectVoice]);
const speak = useCallback(
(text: string, lang?: string) => {
Iif (!synthRef.current || !isSupported) {
setError("このブラウザは読み上げ機能に対応していません");
return;
}
// 既存の読み上げをキャンセル
synthRef.current.cancel();
setError(null);
const detectedLang = lang || detectLanguage(text);
currentLangRef.current = detectedLang;
chunksRef.current = splitIntoChunks(text);
currentChunkIndexRef.current = 0;
// 音声リストの読み込みを待つ
setStatus("loading");
const startSpeaking = () => {
speakNextChunk();
};
if (synthRef.current.getVoices().length > 0) {
startSpeaking();
} else E{
synthRef.current.addEventListener("voiceschanged", startSpeaking, {
once: true,
});
}
},
[isSupported, detectLanguage, splitIntoChunks, speakNextChunk],
);
const pause = useCallback(() => {
if (synthRef.current && status === "playing") {
synthRef.current.pause();
setStatus("paused");
}
}, [status]);
const resume = useCallback(() => {
if (synthRef.current && status === "paused") {
synthRef.current.resume();
setStatus("playing");
}
}, [status]);
const stop = useCallback(() => {
if (synthRef.current) {
synthRef.current.cancel();
chunksRef.current = [];
currentChunkIndexRef.current = 0;
setStatus("idle");
}
}, []);
const setRate = useCallback((newRate: number) => {
const clampedRate = Math.max(MIN_RATE, Math.min(MAX_RATE, newRate));
setRateState(clampedRate);
}, []);
return {
status,
rate,
isSupported,
error,
speak,
pause,
resume,
stop,
setRate,
};
};
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