"""Voice activity detection."""
from typing import Optional


class SileroVad:
    """Voice activity detection with silero VAD."""

    def __init__(self, threshold: float, trigger_level: int) -> None:
        from pysilero_vad import SileroVoiceActivityDetector

        self.detector = SileroVoiceActivityDetector()
        self.threshold = threshold
        self.trigger_level = trigger_level
        self._activation = 0

    def __call__(self, audio_bytes: Optional[bytes]) -> bool:
        if audio_bytes is None:
            # Reset
            self._activation = 0
            self.detector.reset()
            return False

        if self.detector(audio_bytes) >= self.threshold:
            # Speech detected
            self._activation += 1
            if self._activation >= self.trigger_level:
                self._activation = 0
                return True
        else:
            # Silence detected
            self._activation = max(0, self._activation - 1)

        return False