"""GStreamer ALSA capture graphs for the shared audio daemon."""
from __future__ import annotations

import shutil

GST_LAUNCH = shutil.which("gst-launch-1.0") or "gst-launch-1.0"
GST_GROUP_SIZE = 5


def shared_audio_cmd(
    cameras: list[tuple[str, int]],
    rate: int,
    fds: list[int],
) -> list[str]:
    if len(cameras) != len(fds):
        raise ValueError("cameras and fds length mismatch")
    cmd: list[str] = [GST_LAUNCH, "-q"]
    caps = f"audio/x-raw,format=S16LE,rate={int(rate)},channels=2"
    for (_ident, card), fd in zip(cameras, fds):
        cmd += [
            "alsasrc", f"device=hw:{int(card)},0", "do-timestamp=false",
            "!", caps,
            "!", "queue", "max-size-buffers=2", "max-size-bytes=0",
            "max-size-time=0", "leaky=downstream",
            "!", "fdsink", f"fd={int(fd)}", "sync=false",
        ]
    return cmd


def grouped_audio(
    cameras: list[tuple[str, int]],
    fds: list[int],
    group_size: int = GST_GROUP_SIZE,
) -> list[tuple[list[tuple[str, int]], list[int]]]:
    if group_size < 1:
        raise ValueError("group_size must be >= 1")
    out = []
    for i in range(0, len(cameras), group_size):
        out.append((cameras[i:i + group_size], fds[i:i + group_size]))
    return out