// ─── Audio playback hook — receives PCM from WebSocket and plays through Web Audio API ──
import { useCallback, useRef, useState } from "react";

const SAMPLE_RATE = 24000;
const CHANNELS = 1;

export function useAudioPlayback() {
  const [isListening, setIsListening] = useState(false);
  const [levels, setLevels] = useState<number[]>(Array.from({ length: 32 }, () => 0.04));
  const audioContextRef = useRef<AudioContext | null>(null);
  const userTimelinesRef = useRef(new Map<number, number>());

  const handleIncomingPcm = useCallback((data: ArrayBuffer) => {
    const headerView = new DataView(data, 0, 4);
    const userIdHash = headerView.getInt32(0, true);
    const audioData = data.slice(4);
    const int16Array = new Int16Array(audioData);
    let sum = 0;
    for (const sample of int16Array) sum += Math.abs(sample / 32768);
    const average = int16Array.length ? sum / int16Array.length : 0;
    setLevels((prev) =>
      prev.map((_, index) =>
        Math.max(0.04, average * (0.5 + Math.sin(index * 0.6 + Date.now() / 140) * 0.35 + 0.65) * 5),
      ),
    );

    const audioContext = audioContextRef.current;
    if (!isListening || !audioContext) return;
    const float32Array = new Float32Array(int16Array.length);
    for (let i = 0; i < int16Array.length; i++) float32Array[i] = int16Array[i] / 32768;
    const audioBuffer = audioContext.createBuffer(CHANNELS, float32Array.length / SAMPLE_RATE, SAMPLE_RATE);
    audioBuffer.getChannelData(0).set(float32Array);
    const source = audioContext.createBufferSource();
    source.buffer = audioBuffer;
    source.connect(audioContext.destination);
    const currentTime = audioContext.currentTime;
    let nextStart = userTimelinesRef.current.get(userIdHash) || 0;
    if (nextStart < currentTime) nextStart = currentTime + 0.05;
    source.start(nextStart);
    userTimelinesRef.current.set(userIdHash, nextStart + audioBuffer.duration);
  }, [isListening]);

  const toggleListening = useCallback(async () => {
    if (isListening) {
      await audioContextRef.current?.suspend();
      userTimelinesRef.current.clear();
      setIsListening(false);
      return;
    }
    const AudioContextCtor = window.AudioContext || (window as unknown as { webkitAudioContext: typeof AudioContext }).webkitAudioContext;
    audioContextRef.current ??= new AudioContextCtor({ sampleRate: SAMPLE_RATE });
    await audioContextRef.current.resume();
    setIsListening(true);
  }, [isListening]);

  return { isListening, levels, handleIncomingPcm, toggleListening, audioContextRef };
}