nexus/ui/src/hooks/usePiperTts.ts

import { useState, useCallback, useRef } from "react";
import { tts } from "@mintplex-labs/piper-tts-web";

const DEFAULT_VOICE = "en_US-hfc_female-medium";

export type TtsStatus = "idle" | "downloading" | "ready" | "speaking" | "error";

export function usePiperTts() {
  const [status, setStatus] = useState<TtsStatus>("idle");
  const [progress, setProgress] = useState(0);
  const audioRef = useRef<HTMLAudioElement | null>(null);

  const prewarm = useCallback(async () => {
    if (status === "ready" || status === "downloading") return;
    setStatus("downloading");
    setProgress(0);
    try {
      const stored = await tts.stored();
      if (!stored.includes(DEFAULT_VOICE)) {
        await tts.download(DEFAULT_VOICE, (p: { loaded: number; total: number }) => {
          setProgress(Math.round((p.loaded / p.total) * 100));
        });
      }
      setStatus("ready");
      setProgress(100);
    } catch {
      setStatus("error");
    }
  }, [status]);

  const speak = useCallback(async (text: string) => {
    if (status !== "ready") return;
    // Stop any currently playing audio
    if (audioRef.current) {
      audioRef.current.pause();
      audioRef.current = null;
    }
    setStatus("speaking");
    try {
      const wav = await tts.predict({ text, voiceId: DEFAULT_VOICE });
      const audio = new Audio(wav);
      audioRef.current = audio;
      audio.onended = () => {
        audioRef.current = null;
        setStatus("ready");
      };
      audio.onerror = () => {
        audioRef.current = null;
        setStatus("ready");
      };
      await audio.play();
    } catch {
      setStatus("ready");
    }
  }, [status]);

  const stop = useCallback(() => {
    if (audioRef.current) {
      audioRef.current.pause();
      audioRef.current = null;
    }
    if (status === "speaking") setStatus("ready");
  }, [status]);

  return { status, progress, prewarm, speak, stop };
}