#!/bin/bash
# Bridges USB gadget host volume (Windows slider) -> ES8323 sink volume/mute.
# Host speaker volume appears on UAC2Gadget control numid=7 (PCM Capture Volume);
# f_uac2 exposes it but does not scale samples, so we apply it here.
set -u
export XDG_RUNTIME_DIR=/run/user/1000
CARD=UAC2Gadget
SINK=alsa_output.platform-es8323-sound.stereo-fallback
apply() {
  local v m
  v=$(amixer -c "$CARD" cget numid=7 2>/dev/null | awk -F= '/: values=/{print $2; exit}')
  m=$(amixer -c "$CARD" cget numid=6 2>/dev/null | awk -F= '/: values=/{print $2; exit}')
  [ -z "$v" ] && return 0
  pactl set-sink-volume "$SINK" "${v}%" 2>/dev/null
  case "$m" in
    off|0) pactl set-sink-mute "$SINK" 1 2>/dev/null ;;
    *)     pactl set-sink-mute "$SINK" 0 2>/dev/null ;;
  esac
}
apply
stdbuf -oL alsactl monitor hw:"$CARD" 2>/dev/null | while IFS= read -r _l; do apply; done