import threading
import pydub
import av
import streamlit as st # Only imported for st.session_state access in recv method
from streamlit_webrtc import AudioProcessorBase

class AudioBufferProcessor(AudioProcessorBase):
    """
    An audio processor that buffers incoming audio frames.
    It accumulates audio only when `st.session_state.is_recording` is True.
    """
    def __init__(self) -> None:
        self._audio_buffer = pydub.AudioSegment.empty()
        self._lock = threading.Lock() # Use a lock for thread-safe access to the buffer

    def recv(self, frame: av.AudioFrame) -> None:
        """
        Receives audio frames from the WebRTC stream.
        If recording is active, appends the frame to the internal buffer.
        """
        if st.session_state.is_recording:
            sound = pydub.AudioSegment(
                data=frame.to_ndarray().tobytes(),
                sample_width=frame.format.bytes,
                frame_rate=frame.sample_rate,
                channels=len(frame.layout.channels),
            )
            sound = sound.set_channels(1).set_frame_rate(16000)
            with self._lock:
                self._audio_buffer += sound

    def get_and_clear_buffered_audio(self) -> pydub.AudioSegment:
        """
        Retrieves the accumulated audio and clears the buffer.
        This method is called when recording stops.
        """
        with self._lock:
            recorded_audio = self._audio_buffer
            self._audio_buffer = pydub.AudioSegment.empty() # Clear the buffer
            return recorded_audio