"""In-memory PCM ring buffer for a single utterance.

Kept deliberately dependency-free (REQ-002). The buffer accumulates the
current utterance's PCM and is flushed at end-of-speech, so STT always
transcribes one utterance, not a rolling window.
"""
from __future__ import annotations


class PCMBuffer:
    def __init__(self) -> None:
        self._chunks: list[bytes] = []
        self._bytes = 0

    def feed(self, pcm: bytes) -> None:
        self._chunks.append(bytes(pcm))
        self._bytes += len(pcm)

    def total_bytes(self) -> int:
        return self._bytes

    def get(self) -> bytes:
        data = b"".join(self._chunks)
        self.clear()
        return data

    def clear(self) -> None:
        self._chunks = []
        self._bytes = 0