"use client";

import { useCallback, useEffect, useRef } from "react";
import { plainTextForSpeech } from "@/lib/voiceText";

function pickKoreanVoice(): SpeechSynthesisVoice | null {
  if (typeof window === "undefined" || !window.speechSynthesis) return null;
  return window.speechSynthesis.getVoices().find((v) => v.lang.startsWith("ko")) ?? null;
}

export function useBrowserTts() {
  const utterRef = useRef<SpeechSynthesisUtterance | null>(null);

  useEffect(() => {
    if (typeof window === "undefined" || !window.speechSynthesis) return;
    const onVoices = () => pickKoreanVoice();
    window.speechSynthesis.addEventListener("voiceschanged", onVoices);
    return () => window.speechSynthesis.removeEventListener("voiceschanged", onVoices);
  }, []);

  const stop = useCallback(() => {
    window.speechSynthesis?.cancel();
    utterRef.current = null;
  }, []);

  const speak = useCallback(
    (text: string, enabled: boolean): Promise<void> => {
      if (!enabled || !text.trim() || typeof window === "undefined" || !window.speechSynthesis) {
        return Promise.resolve();
      }

      stop();
      const spoken = plainTextForSpeech(text);
      if (!spoken) return Promise.resolve();

      return new Promise((resolve) => {
        const utter = new SpeechSynthesisUtterance(spoken);
        utter.lang = "ko-KR";
        utter.rate = 1;
        const ko = pickKoreanVoice();
        if (ko) utter.voice = ko;
        utter.onend = () => resolve();
        utter.onerror = () => resolve();
        utterRef.current = utter;
        window.speechSynthesis.resume();
        window.speechSynthesis.speak(utter);
      });
    },
    [stop],
  );

  return { speak, stop, supported: typeof window !== "undefined" && !!window.speechSynthesis };
}