"""Duck (lower) media volume during recording via PulseAudio/PipeWire."""

import re
import shutil
import subprocess

_saved_volumes: dict[int, str] = {}


def _pactl_available() -> bool:
    return shutil.which("pactl") is not None


def _get_sink_inputs() -> list[tuple[int, str]]:
    """Return list of (sink_input_index, current_volume_string)."""
    try:
        out = subprocess.run(
            ["pactl", "list", "sink-inputs"],
            capture_output=True, text=True, timeout=3,
        ).stdout
    except (subprocess.TimeoutExpired, FileNotFoundError):
        return []

    results = []
    current_idx = None
    for line in out.splitlines():
        m = re.match(r"Sink Input #(\d+)", line)
        if m:
            current_idx = int(m.group(1))
            continue
        if current_idx is not None and "Volume:" in line:
            results.append((current_idx, line.strip()))
            current_idx = None
    return results


def _parse_percent(vol_line: str) -> int | None:
    """Extract first percentage value from a Volume: line."""
    m = re.search(r"(\d+)%", vol_line)
    return int(m.group(1)) if m else None


def duck(duck_percent: int = 20) -> None:
    """Lower all sink inputs to duck_percent of their current volume."""
    _saved_volumes.clear()
    if not _pactl_available():
        return
    for idx, vol_line in _get_sink_inputs():
        pct = _parse_percent(vol_line)
        if pct is not None:
            _saved_volumes[idx] = f"{pct}%"
            ducked = max(1, int(pct * duck_percent / 100))
            try:
                subprocess.run(
                    ["pactl", "set-sink-input-volume", str(idx), f"{ducked}%"],
                    check=False, timeout=2,
                )
            except (subprocess.TimeoutExpired, FileNotFoundError):
                pass


def unduck() -> None:
    """Restore all sink inputs to their saved volumes."""
    if not _pactl_available():
        return
    for idx, vol in _saved_volumes.items():
        try:
            subprocess.run(
                ["pactl", "set-sink-input-volume", str(idx), vol],
                check=False, timeout=2,
            )
        except (subprocess.TimeoutExpired, FileNotFoundError):
            pass
    _saved_volumes.clear()