import { useRef, useState, useCallback } from 'react';

export interface AudioData {
  leftChannel: Float32Array;
  rightChannel: Float32Array;
  sampleRate: number;
  duration: number;
}

export function useAudioAnalyzer() {
  const [audioData, setAudioData] = useState<AudioData | null>(null);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [fileName, setFileName] = useState<string | null>(null);
  const [originalFile, setOriginalFile] = useState<File | null>(null);
  const audioContextRef = useRef<AudioContext | null>(null);

  const loadAudioFile = useCallback(async (file: File) => {
    setIsLoading(true);
    setError(null);
    setFileName(file.name);
    setOriginalFile(file);

    try {
      // Create or reuse AudioContext
      if (!audioContextRef.current) {
        audioContextRef.current = new AudioContext();
      }
      const audioContext = audioContextRef.current;

      // Read file as ArrayBuffer
      const arrayBuffer = await file.arrayBuffer();
      
      // Decode audio data
      const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);
      
      // Extract channel data
      const leftChannel = audioBuffer.getChannelData(0);
      const rightChannel = audioBuffer.numberOfChannels > 1 
        ? audioBuffer.getChannelData(1) 
        : audioBuffer.getChannelData(0); // Mono: duplicate left channel

      setAudioData({
        leftChannel: new Float32Array(leftChannel),
        rightChannel: new Float32Array(rightChannel),
        sampleRate: audioBuffer.sampleRate,
        duration: audioBuffer.duration,
      });
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to load audio file');
      setAudioData(null);
    } finally {
      setIsLoading(false);
    }
  }, []);

  const reset = useCallback(() => {
    setAudioData(null);
    setFileName(null);
    setOriginalFile(null);
    setError(null);
  }, []);

  return {
    audioData,
    isLoading,
    error,
    fileName,
    originalFile,
    loadAudioFile,
    reset,
  };
}