"""Per-hop noise gate for C920 mics (LiveKit active-speaker needs distinct energy)."""
from __future__ import annotations

import numpy as np

FLOOR_DB = -120.0


def rms_dbfs(pcm: np.ndarray) -> float:
    """RMS of int16 PCM in dBFS. Empty/zero -> FLOOR_DB."""
    x = np.asarray(pcm)
    if x.size == 0:
        return FLOOR_DB
    rms = float(np.sqrt(np.mean(np.square(x.astype(np.float64) / 32768.0))))
    if rms <= 1e-12:
        return FLOOR_DB
    return 20.0 * float(np.log10(rms))


def hop_mono_int16(pcm: np.ndarray) -> np.ndarray:
    x = np.asarray(pcm)
    if x.ndim == 2:
        return np.mean(x.astype(np.float32), axis=1).astype(np.int16)
    return np.asarray(x, dtype=np.int16)


def gate_enabled_for(identity: str, speaker_camera: str, enabled: bool) -> bool:
    """Dante/rally stays ungated; C920 seats are gated when enabled."""
    if not enabled:
        return False
    ident = (identity or "").strip()
    skip = (speaker_camera or "").strip()
    if ident and skip and ident == skip:
        return False
    return True


def hold_hops(hold_s: float, hop_s: float) -> int:
    hop = max(1e-6, float(hop_s))
    return max(1, int(round(float(hold_s) / hop)))


def make_gate(
    identity: str,
    speaker_camera: str,
    enabled: bool,
    open_db: float,
    close_db: float,
    hold_s: float,
    hop_s: float,
) -> HopGate | None:
    if not gate_enabled_for(identity, speaker_camera, enabled):
        return None
    return HopGate(
        open_db=open_db,
        close_db=close_db,
        hold_hops=hold_hops(hold_s, hop_s),
    )


class HopGate:
    """Open on close-talk energy; hangover then mute so neighbors stay silent."""

    def __init__(
        self,
        open_db: float = -32.0,
        close_db: float = -40.0,
        hold_hops: int = 3,
    ) -> None:
        self.open_db = float(open_db)
        self.close_db = min(float(close_db), self.open_db)
        self.hold_hops = max(0, int(hold_hops))
        self.open = False
        self.hold = 0

    def apply(self, pcm: np.ndarray) -> np.ndarray:
        pcm = np.asarray(pcm, dtype=np.int16)
        db = rms_dbfs(pcm)
        if db >= self.open_db:
            self.open = True
            self.hold = self.hold_hops
            return pcm
        if self.open:
            if db >= self.close_db:
                self.hold = self.hold_hops
                return pcm
            if self.hold > 0:
                self.hold -= 1
                return pcm
            self.open = False
        return np.zeros_like(pcm)