audio-ui/lib/hooks/useRecording.ts

'use client';

import * as React from 'react';

export interface RecordingState {
  isRecording: boolean;
  isPaused: boolean;
  duration: number;
  inputLevel: number;
}

export interface RecordingSettings {
  inputGain: number; // 0.0 to 2.0 (1.0 = unity)
  recordMono: boolean; // true = mono, false = stereo
  sampleRate: number; // target sample rate (44100, 48000, etc.)
}

export interface UseRecordingReturn {
  state: RecordingState;
  settings: RecordingSettings;
  startRecording: () => Promise<void>;
  stopRecording: () => Promise<AudioBuffer | null>;
  pauseRecording: () => void;
  resumeRecording: () => void;
  getInputDevices: () => Promise<MediaDeviceInfo[]>;
  selectInputDevice: (deviceId: string) => Promise<void>;
  requestPermission: () => Promise<boolean>;
  setInputGain: (gain: number) => void;
  setRecordMono: (mono: boolean) => void;
  setSampleRate: (sampleRate: number) => void;
}

export function useRecording(): UseRecordingReturn {
  const [state, setState] = React.useState<RecordingState>({
    isRecording: false,
    isPaused: false,
    duration: 0,
    inputLevel: 0,
  });

  const [settings, setSettings] = React.useState<RecordingSettings>({
    inputGain: 1.0,
    recordMono: false,
    sampleRate: 48000,
  });

  const mediaRecorderRef = React.useRef<MediaRecorder | null>(null);
  const audioContextRef = React.useRef<AudioContext | null>(null);
  const analyserRef = React.useRef<AnalyserNode | null>(null);
  const gainNodeRef = React.useRef<GainNode | null>(null);
  const streamRef = React.useRef<MediaStream | null>(null);
  const chunksRef = React.useRef<Blob[]>([]);
  const startTimeRef = React.useRef<number>(0);
  const animationFrameRef = React.useRef<number>(0);
  const selectedDeviceIdRef = React.useRef<string>('');
  const isMonitoringRef = React.useRef<boolean>(false);

  // Request microphone permission
  const requestPermission = React.useCallback(async (): Promise<boolean> => {
    try {
      const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
      stream.getTracks().forEach((track) => track.stop());
      return true;
    } catch (error) {
      console.error('Microphone permission denied:', error);
      return false;
    }
  }, []);

  // Get available input devices
  const getInputDevices = React.useCallback(async (): Promise<MediaDeviceInfo[]> => {
    try {
      const devices = await navigator.mediaDevices.enumerateDevices();
      return devices.filter((device) => device.kind === 'audioinput');
    } catch (error) {
      console.error('Failed to enumerate devices:', error);
      return [];
    }
  }, []);

  // Select input device
  const selectInputDevice = React.useCallback(async (deviceId: string): Promise<void> => {
    selectedDeviceIdRef.current = deviceId;
  }, []);

  // Convert linear amplitude to dB scale normalized to 0-1 range
  const linearToDbScale = React.useCallback((linear: number): number => {
    if (linear === 0) return 0;

    // Convert to dB (20 * log10(linear))
    const db = 20 * Math.log10(linear);

    // Normalize -60dB to 0dB range to 0-1
    // -60dB or lower = 0%, 0dB = 100%
    const minDb = -60;
    const maxDb = 0;
    const normalized = (db - minDb) / (maxDb - minDb);

    // Clamp to 0-1 range
    return Math.max(0, Math.min(1, normalized));
  }, []);

  // Monitor input level
  const monitorInputLevel = React.useCallback(() => {
    if (!analyserRef.current) return;

    const analyser = analyserRef.current;
    const dataArray = new Float32Array(analyser.fftSize);

    const updateLevel = () => {
      if (!isMonitoringRef.current) return;

      analyser.getFloatTimeDomainData(dataArray);

      // Calculate peak level using float data (-1 to +1 range)
      let peak = 0;
      for (let i = 0; i < dataArray.length; i++) {
        const abs = Math.abs(dataArray[i]);
        if (abs > peak) {
          peak = abs;
        }
      }

      // Convert linear peak to logarithmic dB scale
      const dbLevel = linearToDbScale(peak);

      setState((prev) => ({ ...prev, inputLevel: dbLevel }));

      animationFrameRef.current = requestAnimationFrame(updateLevel);
    };

    updateLevel();
  }, [linearToDbScale]);

  // Start recording
  const startRecording = React.useCallback(async (): Promise<void> => {
    try {
      // Get user media with selected device
      const constraints: MediaStreamConstraints = {
        audio: selectedDeviceIdRef.current
          ? { deviceId: { exact: selectedDeviceIdRef.current } }
          : true,
      };

      const stream = await navigator.mediaDevices.getUserMedia(constraints);
      streamRef.current = stream;

      // Create audio context with target sample rate
      const audioContext = new AudioContext({ sampleRate: settings.sampleRate });
      audioContextRef.current = audioContext;

      const source = audioContext.createMediaStreamSource(stream);

      // Create gain node for input gain control
      const gainNode = audioContext.createGain();
      gainNode.gain.value = settings.inputGain;
      gainNodeRef.current = gainNode;

      // Create analyser for level monitoring
      const analyser = audioContext.createAnalyser();
      analyser.fftSize = 256;
      analyser.smoothingTimeConstant = 0.3;

      // Connect: source -> gain -> analyser
      source.connect(gainNode);
      gainNode.connect(analyser);
      analyserRef.current = analyser;

      // Create MediaRecorder
      const mediaRecorder = new MediaRecorder(stream);
      mediaRecorderRef.current = mediaRecorder;
      chunksRef.current = [];

      mediaRecorder.ondataavailable = (event) => {
        if (event.data.size > 0) {
          chunksRef.current.push(event.data);
        }
      };

      // Start recording
      mediaRecorder.start();
      startTimeRef.current = Date.now();

      setState({
        isRecording: true,
        isPaused: false,
        duration: 0,
        inputLevel: 0,
      });

      // Start monitoring input level
      isMonitoringRef.current = true;
      monitorInputLevel();
    } catch (error) {
      console.error('Failed to start recording:', error);
      throw error;
    }
  }, [monitorInputLevel, settings.sampleRate, settings.inputGain]);

  // Stop recording and return AudioBuffer
  const stopRecording = React.useCallback(async (): Promise<AudioBuffer | null> => {
    return new Promise((resolve) => {
      if (!mediaRecorderRef.current || !streamRef.current) {
        resolve(null);
        return;
      }

      const mediaRecorder = mediaRecorderRef.current;

      mediaRecorder.onstop = async () => {
        // Stop all tracks
        streamRef.current?.getTracks().forEach((track) => track.stop());

        // Create blob from recorded chunks
        const blob = new Blob(chunksRef.current, { type: 'audio/webm' });

        // Convert blob to AudioBuffer
        try {
          const arrayBuffer = await blob.arrayBuffer();
          const audioContext = new AudioContext();
          let audioBuffer = await audioContext.decodeAudioData(arrayBuffer);

          // Convert to mono if requested
          if (settings.recordMono && audioBuffer.numberOfChannels > 1) {
            const monoBuffer = audioContext.createBuffer(
              1,
              audioBuffer.length,
              audioBuffer.sampleRate
            );
            const monoData = monoBuffer.getChannelData(0);

            // Mix all channels to mono by averaging
            for (let i = 0; i < audioBuffer.length; i++) {
              let sum = 0;
              for (let channel = 0; channel < audioBuffer.numberOfChannels; channel++) {
                sum += audioBuffer.getChannelData(channel)[i];
              }
              monoData[i] = sum / audioBuffer.numberOfChannels;
            }

            audioBuffer = monoBuffer;
          }

          // Clean up
          isMonitoringRef.current = false;
          if (audioContextRef.current) {
            await audioContextRef.current.close();
          }
          if (animationFrameRef.current) {
            cancelAnimationFrame(animationFrameRef.current);
          }

          setState({
            isRecording: false,
            isPaused: false,
            duration: 0,
            inputLevel: 0,
          });

          resolve(audioBuffer);
        } catch (error) {
          console.error('Failed to decode recorded audio:', error);
          resolve(null);
        }
      };

      mediaRecorder.stop();
    });
  }, [settings.recordMono]);

  // Pause recording
  const pauseRecording = React.useCallback(() => {
    if (mediaRecorderRef.current && state.isRecording && !state.isPaused) {
      mediaRecorderRef.current.pause();
      setState((prev) => ({ ...prev, isPaused: true }));

      isMonitoringRef.current = false;
      if (animationFrameRef.current) {
        cancelAnimationFrame(animationFrameRef.current);
      }
    }
  }, [state.isRecording, state.isPaused]);

  // Resume recording
  const resumeRecording = React.useCallback(() => {
    if (mediaRecorderRef.current && state.isRecording && state.isPaused) {
      mediaRecorderRef.current.resume();
      setState((prev) => ({ ...prev, isPaused: false }));
      isMonitoringRef.current = true;
      monitorInputLevel();
    }
  }, [state.isRecording, state.isPaused, monitorInputLevel]);

  // Update duration
  React.useEffect(() => {
    if (!state.isRecording || state.isPaused) return;

    const interval = setInterval(() => {
      const elapsed = (Date.now() - startTimeRef.current) / 1000;
      setState((prev) => ({ ...prev, duration: elapsed }));
    }, 100);

    return () => clearInterval(interval);
  }, [state.isRecording, state.isPaused]);

  // Cleanup on unmount
  React.useEffect(() => {
    return () => {
      isMonitoringRef.current = false;
      if (streamRef.current) {
        streamRef.current.getTracks().forEach((track) => track.stop());
      }
      if (audioContextRef.current) {
        audioContextRef.current.close();
      }
      if (animationFrameRef.current) {
        cancelAnimationFrame(animationFrameRef.current);
      }
    };
  }, []);

  // Settings setters
  const setInputGain = React.useCallback((gain: number) => {
    setSettings((prev) => ({ ...prev, inputGain: Math.max(0, Math.min(2, gain)) }));
    // Update gain node if recording
    if (gainNodeRef.current) {
      gainNodeRef.current.gain.value = Math.max(0, Math.min(2, gain));
    }
  }, []);

  const setRecordMono = React.useCallback((mono: boolean) => {
    setSettings((prev) => ({ ...prev, recordMono: mono }));
  }, []);

  const setSampleRate = React.useCallback((sampleRate: number) => {
    setSettings((prev) => ({ ...prev, sampleRate }));
  }, []);

  return {
    state,
    settings,
    startRecording,
    stopRecording,
    pauseRecording,
    resumeRecording,
    getInputDevices,
    selectInputDevice,
    requestPermission,
    setInputGain,
    setRecordMono,
    setSampleRate,
  };
}