#!/bin/sh
#
# pulserecorder — record a source via Pulse
#
# Synopsis:
#   pulserecorder -i <index> [-o filename.ogg] [-f]
#   pulserecorder -l         [-o filename.ogg] [-f]
#   pulserecorder            [-o filename.ogg] [-f]
#
# The first form records sound from the sink-input with index <index> to the
# filename specified, or one generated using a UUID.
#
# The second form records sound from the sink-input with the highest index,
# i.e. the latest one to start playing.
#
# The third form waits for a new sink-input to appear, and will record that.
#
# Copyright © 2020 martin f. krafft <madduck@madduck.net>
# Released under the teams of the Artistic Licence 2.0
#
set -eu

cleanup_commands=
cleanup() {
  set +e
  eval $cleanup_commands 2>/dev/null
  trap - 1 2 3 4 5 6 7 8 10 11 12 13 14 15
}
trap cleanup 1 2 3 4 5 6 7 8 10 11 12 13 14 15
cleanup_hook() {
  cleanup_commands="$@${cleanup_commands:+; $cleanup_commands}"
}

if [ -z "${TMPDIR:-}" ]; then
  TMPDIR=/tmp
fi
for i in $LOGNAME volatile; do
  if [ -d "${TMPDIR}/$i" ]; then
    TMPDIR="${TMPDIR}/$i"
    break
  fi
done
export TMPDIR
TMPDIR=$(mktemp -dp "$TMPDIR" parec.XXXXXXXXXX)
cleanup_hook rm -r $TMPDIR


state= outfile= index= clobber=0
for arg in "$@"; do
  case "$state/$arg" in
    (/-i) state=i;;
    (i/*) index="$arg"; state=;;

    (/-l) index="last";;

    (/-o) state=o;;
    (o/*) outfile="$arg"; state=;;

    (/-f) clobber=1;;
  esac
done

pa_subscribe() {
  ( pactl subscribe 2>/dev/null & echo $! )
}
pa_wait_for_event() {
  local type event id;
  type="${1:-*}" event="${2:-*}" id="${3:-*}"
  pa_subscribe | (
    read pid
    #echo >&2 pa_subscribe started with PID $pid
    while read lead xevent on xtype xid; do
      xid=${xid#\#}
      #echo >&2 "pa_subscribe: $xtype/$xevent/$xid ($type/$event/$id)"
      case "$xtype/$xevent/$xid" in
        ($type/"'$event'"/$id) echo "$xtype $xevent $xid"; break;;
        (*) :;;
      esac
    done
    kill $pid
  )
}
pa_get_next_index() {
  pa_wait_for_event sink-input new | {
    read type event id
    echo $id
  }
}

case "$index" in

  (last)
    index=$(pactl list short sink-inputs | sed -rne '$s,([[:digit:]]+)[[:space:]].*,\1,p')
    ;;

  (*[^0-9]*)
    echo >&2 "E: non-numeric index: $index"
    exit 1
    ;;

  (*[0-9]*) :;;

  (*)
    echo >&2 "Listening for pulseaudio event… "
    index=$(pa_get_next_index)
    ;;

esac

if [ -z "$index" ]; then

  echo >&2 E: no index specified or discernable.
  exit 1
fi

uuidgen() {
  hascmd() { command -v "$@" >/dev/null;}
  if   hascmd uuid; then uuid
  elif hascmd uuidgen; then uuidgen
  elif hascmd python3; then
    python3 -c 'import uuid; print(uuid.uuid1())'
  elif hascmd python; then
    python -c 'import uuid; print(uuid.uuid1())'
  else
    dd if=/dev/urandom bs=16 count=1 status=none | base64
  fi
}

uuid=$(uuidgen)

[ -n "$outfile" ] || outfile="${uuid}.ogg"

if [ -f "$outfile" ] && [ $clobber -eq 0 ]; then
  echo >&2 "E: file exists, and -f not given: $outfile"
  exit 1
fi

devname="record-to-file-${uuid}"

echo >&2 "Recording source $index to $outfile …"

load_module() {
  local id mod sink desc
  mod="$1" sink="$2" desc="$3"; shift 3
  id=$(pactl load-module "$mod" sink_name="$sink" "$@")
  cleanup_hook pactl unload-module $id
  pacmd update-sink-proplist "$sink" device.description="$desc"
}

move_source_to_sink() {
  local c;
  c=$(pactl list short sink-inputs | sed -rne "s,^${1}[[:space:]]+([[:digit:]]+).+,\1,p")
  cleanup_hook pactl move-sink-input $1 $c
  pactl move-sink-input $1 $2
}

if false; then
  # This would be great, but it does not work. For instance, trying this on
  # audible meant that audible would play at maximum speed (3h played in 3
  # minutes), but the result would be full of skips, making me think that
  # something in the local pipeline can't handle the throughput. Rate-limiting
  # might work. Have not had the time to investigate further.

  load_module module-pipe-sink "$devname" "$devname" file="$TMPDIR/outfifo"
  move_source_to_sink $index "$devname"
  oggenc --raw -q5 -o "$outfile" "$TMPDIR/outfifo" || :
  #pv -pterb "$TMPDIR/outfifo" > $TMPDIR/outfile.wav || :

else
  # More traditional approach, which just takes 1:1 time.

  load_module module-null-sink "$devname" "$devname"
  move_source_to_sink $index "$devname"
  parec --format=s16le -d "${devname}.monitor" 2>/dev/null \
    | oggenc --raw -q5 -o "$outfile" - &
  pid=$!

  pa_wait_for_event sink-input remove $index >/dev/null

  kill $pid
fi

cleanup